B&W film developing

[Thor Legvold]

Quick question for the people here on the list(s).

I’m working on getting my exposure and developmen dialed in, and have read some conflicting info.

"Expose for shadows, develop for highlights" seems to be the mantra.

Ansel would like every exposure to be visualized, exposed accordingly and developed individually to adjust for contrast. But he used sheet film with 40’s - 50’s emulsions. Some online articles say it doesn’t really matter with modern B&W films and you can’t adjust development for a frame on a roll anyway.

With roll-film and more a more modern emulsion (using APX100 and Tri-X 400), how applicable/neccessary is the full-on zone system?

I’ve been testing “placing” values on different frames and have tried developing at both 5 minutes and 7 minutes, Rodinal 1:25 at 24C in a Jobo (constant agitation). Both tests seemed to provide good results, and now I’m curious how precise I need to be to get the best overall negative with as much printable information as possible. With both nice tonality and good contrast.

My current setup doesn’t allow me to print yet, and I wonder if there’s any way to use f.x. a scanner to measure density or at least confirm that I’m getting the most out of my negatives. I do plan on printing them on paper at some point, but first want to get my exposure and development down as ideally as possible. Sending them off to a lab to have them measured on a densiometer is also an option, if that’s the way to go.

Maybe some of the hardcore analogue guys can weigh in? Daniel, Sanders, Slobodan, Dan?

Thanks,
Thor

[Jon Stanton]

Thor, Thanks for bringing up the topic.... I've been planning on developing numerous rolls of b/w. I don't have a Jobo (wish I did) just several tanks. I'm looking fwd to the feedback.

Olympia, WA

Post by Thor Legvold
Quick question for the people here on the list(s).
I’m working on getting my exposure and developmen dialed in, and have read some conflicting info.
"Expose for shadows, develop for highlights" seems to be the mantra.
Ansel would like every exposure to be visualized, exposed accordingly and developed individually to adjust for contrast. But he used sheet film with 40’s - 50’s emulsions. Some online articles say it doesn’t really matter with modern B&W films and you can’t adjust development for a frame on a roll anyway.
With roll-film and more a more modern emulsion (using APX100 and Tri-X 400), how applicable/neccessary is the full-on zone system?
I’ve been testing “placing” values on different frames and have tried developing at both 5 minutes and 7 minutes, Rodinal 1:25 at 24C in a Jobo (constant agitation). Both tests seemed to provide good results, and now I’m curious how precise I need to be to get the best overall negative with as much printable information as possible. With both nice tonality and good contrast.
My current setup doesn’t allow me to print yet, and I wonder if there’s any way to use f.x. a scanner to measure density or at least confirm that I’m getting the most out of my negatives. I do plan on printing them on paper at some point, but first want to get my exposure and development down as ideally as possible. Sending them off to a lab to have them measured on a densiometer is also an option, if that’s the way to go.
Maybe some of the hardcore analogue guys can weigh in? Daniel, Sanders, Slobodan, Dan?
Thanks,
Thor
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[Chris Burck]

It's pretty amazing what a scanner can pull out of a negative. I've had a
few disasters, begs that i'd have never imagined held anything printable.
But when I was done scanning, sure as heck, there was an image there,
albeit with rather limited tonal scale. My printing experience is almost
nil, so I have no idea what a skilled darkroom worker would've been able to
do, but the scanner (a super cheap clone of a amateur-level microtek--i
think) sure impressed me.

So if your negs are anywhere within a couple stops of being correctly
exposed, I imagine you'll be more than fine. Might require a little more
curves work, is all. And if there's anything like HDR for scanned images,
you probably almost can't go wrong.

[Chris Burck]

Thor,

I've reread your Post, and now realize that I didn't really answer the
question you were asking. My apologies.

Re using a scanner to measure density, if you're really exposing well, it
seems unlikely that you could do this. IINM, scanners typically have less
dynamic range than film. I suppose there might be some sort of technique,
but it would probably require multiple scans and, from there, I have no
idea how you'd interpret the results.

But this is kind of "above my pay grade", so I should probably stop talking
now. . . .

[John Wild]

Thor,

I did a test some years ago with Ilford FP4 and decided ISO 80 worked best for me when developed in Ilfosol S for standard time. I now expose all my B&W at - 1/3 ISO to give a bit extra in the shadows. I have resorted to Rodinal because it seems to keep for ever-and-a-day undiluted in an open bottle (certainly 10 years) - and I like the results.

For a negative scan that I want to get a bit more out of, I make multiple scans, adjusting exposures to get all the dynamic range available using the scanner’s software histogram (Minolta Scan Multi-Pro with Minolta software). Although the dynamic range of the scanner should be able to get all the detail in one pass (D-max 4.2), it does not seem to. Scanning as a transparency gives an unprocessed scan. The scans are default 16-bit; I then reduce to 8-bit in Photoshop and use Photomatix HDR software to amalgamate them to 16-bit files (Photomatix cannot play with 16-bit images – probably too memory hungry). I then make adjustments back in Photoshop and get the images professionally printed. I have never been able to get colour cast free inkjet prints (I have a Canon i950 with 6 inks). I have worked out that by the time I buy a decent printer and do some test prints to get a ‘perfect’ print, I will have used up my pension. ;-)

So I send them away, which probably does not cost much more than a home grown inkjet print.

A multiple scan definitely produces more in the highlights and shadows which are visible on the negative. It takes longer to do but then so would dodging and burning in the darkroom.

I too prefer the smell and watching the image appear but digital dark room has the advantage that you can go off and have a cup of coffee when the need arises and come back again and make minor adjustments to what you have already done – nothing wasted up to that point.

On the whole I do not like HDR digital camera images; I feel that most have been over done and are totally false because there is too much detail. Using a negative, there can only be what is available from the negative from one single exposure. Multiple digital images only works for movement free subjects. With a negative, movement can be captured and images have more ‘feeling’.

These are some of my opinions anyway ;-)

John


On 12/05/2014 01:48, "Chris Burck" <***@gmail.com> wrote:

Thor,

I've reread your Post, and now realize that I didn't really answer the question you were asking. My apologies.

Re using a scanner to measure density, if you're really exposing well, it seems unlikely that you could do this. IINM, scanners typically have less dynamic range than film. I suppose there might be some sort of technique, but it would probably require multiple scans and, from there, I have no idea how you'd interpret the results.

But this is kind of "above my pay grade", so I should probably stop talking now. . . .

[Dan Daniel]

Post by Thor Legvold
With roll-film and more a more modern emulsion (using APX100 and Tri-X 400), how applicable/neccessary is the full-on zone system?

Technically, it isn't possible to do a full-on Zone system with roll
film Unless you use a camera with interchangeable backs like a
Hasselblad and carry 5 backs with you. Or you use a single back and
only shoot a particular dynamic range for each roll of film- 12 Normal+2
shots only today!

There is a program for doing B&W prints using special inksets on inkjet
printers- QTR, quad tone RIP-
http://www.quadtonerip.com/html/QTRoverview.html

It contains methods for developing ICC profiles and using a scanner. I
can't begin to tell you how it works or how well it works, but I will
pass it along if you want to explore if it is applicable for what you
need. One person, Paul Roark, has various articles on using QTR, and one is-
http://www.paulroark.com/BW-Info/QTR-Flatbed.pdf

[Kirk Thompson]

Work-around for 120:

Do the regular zone tests with a compensating-type developer;
Expose for shadow detail (Zone III);
Unless you know the light was flat for the whole roll, develop everything at N-2;
Print to place highlights where they belong, with nice Zone VII-toward-VIII gradation (split-filter printing, if necessary).

Or scan and use a Curve to place the Zones where they belong in an inkjet print. Print on Harman Warmtone Gloss adding the tiniest pinch of Red for warmth. Results will look very close to classic Portriga. Current printers with three black inks do a lovely job on this - you don't need a special inkset.

Kirk




Sent from my iPad

Post by Thor Legvold
With roll-film and more a more modern emulsion (using APX100 and Tri-X 400), how applicable/neccessary is the full-on zone system?

Technically, it isn't possible to do a full-on Zone system with roll film Unless you use a camera with interchangeable backs like a Hasselblad and carry 5 backs with you. Or you use a single back and only shoot a particular dynamic range for each roll of film- 12 Normal+2 shots only today!
There is a program for doing B&W prints using special inksets on inkjet printers- QTR, quad tone RIP-
http://www.quadtonerip.com/html/QTRoverview.html
It contains methods for developing ICC profiles and using a scanner. I can't begin to tell you how it works or how well it works, but I will pass it along if you want to explore if it is applicable for what you need. One person, Paul Roark, has various articles on using QTR, and one is-
http://www.paulroark.com/BW-Info/QTR-Flatbed.pdf
---
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- Online, searchable archives are available at
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[Don Williams]

Post by Thor Legvold
Quick question for the people here on the list(s).

I used to have a densitometer that was originally intended on
measuring exposure on nuclear workers film badges. I recall that it
had a pretty large dynamic range but I never did much with it.

I do have a scanner and have used in on negatives, flat stock, and
transparencies. It's on the low end of the cost range but provides
quality images that are better than any of the prints my kids
make. I will be using it soon to deal with some 1963-65 medium
format transparencies to- Fix exposure on some Underwater slides
that were systematically under-exposed and couldn't be fixed with the
bleach systems in use in those days. I will also be recovering
images from that era that are faded to pink but actually scan and
with a little help are about as good as they were originally.

Now about printing . . . . I remember the old days, picking paper of
the right contrast range, next using varigram(?) paper with filters,
etc. I'm not against chemical systems but I'm perfectly happy with
scanning and printing with an ink-jet printer. That limits me to 8
1/2 X 11 inch prints but they are fine for my use. If I wanted
larger prints I could go to a commercial house and have them print
using chemical processes or even print with one of those larger ink
jet printers.

Anyhow, I have a few thousand B&W negatives that have never been
printed and my intent is to scan them and print digitally. I miss
the smell of chemicals but digital satisfies me.

No intent to start a debate here so just take this as my feeling, not
an argument for any approach.

DAW

[Jon Stanton]

Rodinal lives!
)
(as do Bix & Bird)

Olympia, WA

Post by Thor Legvold
Quick question for the people here on the list(s).

I used to have a densitometer that was originally intended on measuring exposure on nuclear workers film badges. I recall that it had a pretty large dynamic range but I never did much with it.
I do have a scanner and have used in on negatives, flat stock, and transparencies. It's on the low end of the cost range but provides quality images that are better than any of the prints my kids make. I will be using it soon to deal with some 1963-65 medium format transparencies to- Fix exposure on some Underwater slides that were systematically under-exposed and couldn't be fixed with the bleach systems in use in those days. I will also be recovering images from that era that are faded to pink but actually scan and with a little help are about as good as they were originally.
Now about printing . . . . I remember the old days, picking paper of the right contrast range, next using varigram(?) paper with filters, etc. I'm not against chemical systems but I'm perfectly happy with scanning and printing with an ink-jet printer. That limits me to 8 1/2 X 11 inch prints but they are fine for my use. If I wanted larger prints I could go to a commercial house and have them print using chemical processes or even print with one of those larger ink jet printers.
Anyhow, I have a few thousand B&W negatives that have never been printed and my intent is to scan them and print digitally. I miss the smell of chemicals but digital satisfies me.
No intent to start a debate here so just take this as my feeling, not an argument for any approach.
DAW

[Thor Legvold]

Well I just made a very important discovery that will change the way I work forever.

Note to self - Never, ever load two rolls on a Jobo reel, no matter how “safe” it is, how much of a hurry you’re in, or how efficient it seems to process 5 or 6 rolls at a time.

The inner roll developed fine. Both of the outer rolls buckled and stuck to the inner roll, preventing developer from reaching the emulsion, and are completely ruined. While I would have liked to have had the pictures on those rolls, thankfully they weren’t anything critical.

From now on I’m sticking to max 3 rolls at a time - one per reel.

Thor

Post by Jon Stanton
Rodinal lives!
)
(as do Bix & Bird)
Olympia, WA

Post by Thor Legvold
Quick question for the people here on the list(s).

I used to have a densitometer that was originally intended on measuring exposure on nuclear workers film badges. I recall that it had a pretty large dynamic range but I never did much with it.
I do have a scanner and have used in on negatives, flat stock, and transparencies. It's on the low end of the cost range but provides quality images that are better than any of the prints my kids make. I will be using it soon to deal with some 1963-65 medium format transparencies to- Fix exposure on some Underwater slides that were systematically under-exposed and couldn't be fixed with the bleach systems in use in those days. I will also be recovering images from that era that are faded to pink but actually scan and with a little help are about as good as they were originally.
Now about printing . . . . I remember the old days, picking paper of the right contrast range, next using varigram(?) paper with filters, etc. I'm not against chemical systems but I'm perfectly happy with scanning and printing with an ink-jet printer. That limits me to 8 1/2 X 11 inch prints but they are fine for my use. If I wanted larger prints I could go to a commercial house and have them print using chemical processes or even print with one of those larger ink jet printers.
Anyhow, I have a few thousand B&W negatives that have never been printed and my intent is to scan them and print digitally. I miss the smell of chemicals but digital satisfies me.
No intent to start a debate here so just take this as my feeling, not an argument for any approach.
DAW

[Don Williams]

Post by Thor Legvold
The inner roll developed fine. Both of the outer rolls buckled and
stuck to the inner roll, preventing developer from reaching the
emulsion, and are completely ruined. While I would have liked to
have had the pictures on those rolls, thankfully they weren't
anything critical.

Never had that problem when I was using my Nikkor(?) tank. I almost
always did two rolls at once but put them in Back to Back. I agree
that it does take a careful touch to do it but I did have
success. (Actually I think I still have that tank, but less the cap
- lost in moving)

DAW

[Allen Zak]

Paterson reels always worked best for me when developing 2 rolls of 120 at a time. The trick was folding over the leading edge tapes, loading the first roll starting with the trailing end, then feeding in the other starting with the taped end so the two tapes wind up touching. That prevented them from overriding each other. Worked like a charm. Everything else was processed in Nikor (Nikkor being a lens.)

Allen Zak

The inner roll developed fine. Both of the outer rolls buckled and stuck to the inner roll, preventing developer from reaching the emulsion, and are completely ruined. While I would have liked to have had the pictures on those rolls, thankfully they weren’t anything critical.

Never had that problem when I was using my Nikkor(?) tank. I almost always did two rolls at once but put them in Back to Back. I agree that it does take a careful touch to do it but I did have success. (Actually I think I still have that tank, but less the cap - lost in moving)
DAW

[Chris Burck]

"Nikkor being a lens."

Oh, brother. No wonder I couldn't figure out how to load my film! : D

[Don Williams]

Post by Chris Burck
"Nikkor being a lens."
Oh, brother. No wonder I couldn't figure out how to load my film! : D

The strange thing is that during the time I used that can I wasn't
sure who made it, still don't. I am sure it wouldn't take good
pictures, however.

I do have some great binoculars, bought in Japan in 1954 that were
copies of the B&L 7X50's used on the ship. I used them when on
watch. The brand name is Nippon Kogaku, I think the precursor of
Nikon, not sure.

The case is falling apart and the glass is fogged, but Nikon refused
to take them in for overhaul. They are, however, out of
warranty. They were, when new, just as good as the American version.

DAW

[Allen Zak]

Post by Chris Burck
"Nikkor being a lens."
Oh, brother. No wonder I couldn't figure out how to load my film! : D

The strange thing is that during the time I used that can I wasn't sure who made it, still don't. I am sure it wouldn't take good pictures, however.
I do have some great binoculars, bought in Japan in 1954 that were copies of the B&L 7X50's used on the ship. I used them when on watch. The brand name is Nippon Kogaku, I think the precursor of Nikon, not sure.
The case is falling apart and the glass is fogged, but Nikon refused to take them in for overhaul. They are, however, out of warranty. They were, when new, just as good as the American version.
DAW

Nippon Kogaku is the name of the company that produced the Nikon camera line, along with other optical goods, like binoculars. They came to the attention of the world market during the Korean War when well known correspondents, in Japan for R&R and looking for replacements of their worn or damaged German cameras and lenses, discovered Nikon gear to be all but equal to their Leica and Contax counterparts and sometimes better. Their lenses were called Nikkor. For more than 20 years, I did photography with Nikon equipment for my 35 mm requirements (Rollei for most of the rest), found them to be completely reliable and the optics of excellent quality. Eventually, I had to go digital for professional reasons, went with Nikon gear again. Good for the purpose, I suppose, but the relationship just ain’t the same. My film Nikons (and especially the Rolleis) were old friends, the new guys just things. On the other hand, I was much younger then, which might have something to do with my attitude.
However, I love my Nikon binoculars. Really great glass.

[Georges Giralt]

Hello Thor,
An acquaintance has made a thorough tests on, sad for you, HP5+.
He demonstrate that if you want you can expose the 400 ISO film down to
10 EI and get excellent results.
As I use 5x4 and roll film, I've calibrated my process for 5x4 and use
the figures for roll film.

The rationale is to overexpose a bit in order to have something recorded
in the shadows, then get all highlights because modern film have never
ending curves apt to record 10 stops or more.

So the only parameter left is to determine how much time in the dev
you've to use not to get too much contrast to make the negs unprintable
on 00 grade paper.

If I were you, I would take the camera, put the meter at about a half
stop less than the advertised ISO of the film and fill the film with the
same picture of good contrast.
Back in the lab I'll cut the film in 3 parts and develop one for the
"indicated time" in the dev you want to use.
fix, rinse and dry and assert the contrast (scanner, densitometer,
printing, whatever)

If lucky you're done. If not develop another third using either :
A shorter time in the dev if your negs are too contrasty
A longer time in the dev if your negs are not contrasty enough.

If lucky, you're done. If not you still have the third part of the film
to adjust ....

If you're nerdy enough you can adjust the shadow detail on your negs by
adjusting a little the sensitivity dialled on the meter a bit...
Morality : a couple of films, an afternoon in the lab and you're done...

Hope this helps.

P.S. bear in mind that the printing paper does not react as a scanner.
So if you intend to scan your negs ascertain the contrast by using your
scanner and getting proper images on your printer.... Settings can be a
bit different for scanning than for conventional B&W printing.

Post by Thor Legvold
Quick question for the people here on the list(s).
I’m working on getting my exposure and developmen dialed in, and have read some conflicting info.
"Expose for shadows, develop for highlights" seems to be the mantra.
Ansel would like every exposure to be visualized, exposed accordingly and developed individually to adjust for contrast. But he used sheet film with 40’s - 50’s emulsions. Some online articles say it doesn’t really matter with modern B&W films and you can’t adjust development for a frame on a roll anyway.
With roll-film and more a more modern emulsion (using APX100 and Tri-X 400), how applicable/neccessary is the full-on zone system?
I’ve been testing “placing” values on different frames and have tried developing at both 5 minutes and 7 minutes, Rodinal 1:25 at 24C in a Jobo (constant agitation). Both tests seemed to provide good results, and now I’m curious how precise I need to be to get the best overall negative with as much printable information as possible. With both nice tonality and good contrast.
My current setup doesn’t allow me to print yet, and I wonder if there’s any way to use f.x. a scanner to measure density or at least confirm that I’m getting the most out of my negatives. I do plan on printing them on paper at some point, but first want to get my exposure and development down as ideally as possible. Sending them off to a lab to have them measured on a densiometer is also an option, if that’s the way to go.
Maybe some of the hardcore analogue guys can weigh in? Daniel, Sanders, Slobodan, Dan?
Thanks,
Thor
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[Eddy Willems]

I would use Rodinal 1+50 for the development
the results are more repeatebel and the grain very small

Post by Thor Legvold
Quick question for the people here on the list(s).
I’m working on getting my exposure and developmen dialed in, and have read some conflicting info.
"Expose for shadows, develop for highlights" seems to be the mantra.
Ansel would like every exposure to be visualized, exposed accordingly and developed individually to adjust for contrast. But he used sheet film with 40’s - 50’s emulsions. Some online articles say it doesn’t really matter with modern B&W films and you can’t adjust development for a frame on a roll anyway.
With roll-film and more a more modern emulsion (using APX100 and Tri-X 400), how applicable/neccessary is the full-on zone system?
I’ve been testing “placing” values on different frames and have tried developing at both 5 minutes and 7 minutes, Rodinal 1:25 at 24C in a Jobo (constant agitation). Both tests seemed to provide good results, and now I’m curious how precise I need to be to get the best overall negative with as much printable information as possible. With both nice tonality and good contrast.
My current setup doesn’t allow me to print yet, and I wonder if there’s any way to use f.x. a scanner to measure density or at least confirm that I’m getting the most out of my negatives. I do plan on printing them on paper at some point, but first want to get my exposure and development down as ideally as possible. Sending them off to a lab to have them measured on a densiometer is also an option, if that’s the way to go.
Maybe some of the hardcore analogue guys can weigh in? Daniel, Sanders, Slobodan, Dan?
Thanks,
Thor
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[Richard Knoppow]

----- Original Message -----
From: "Thor Legvold" <***@me.com>
To: <***@freelists.org>;
<***@yahoogroups.com>
Sent: Sunday, May 11, 2014 3:00 PM
Subject: [rollei_list] B&W film developing


Quick question for the people here on the list(s).

I’m working on getting my exposure and developmen dialed in,
and have read some conflicting info.

"Expose for shadows, develop for highlights" seems to be the
mantra.

This has already been discussed pretty fully but I will
add something. The characteristics of film were investigated
very thoroughly about eighty years ago by Loyd A. Jones of
Kodak Labs. He wrote several papers most of which were
published in the _Journal of the Franklin Institute_ at the
time a well respected peer reviewed journal of the general
sciences. Jones and his associates continued to publish
research as late as the 1950s. His goal was to discover how
film and paper render the tones of the original scene. Jones
worked out a method of determining film speed. Speed is
simply a way of being able to calculate the correct exposure
when the brightness range of the scene is known and the
transmission of light through the camera optical system is
known. Jones investigated both the effects of varying the
exposure and varying the development. What he found was that
for a given development, that is when the film was processed
to a specified mid-density gamma, and printed, there was a
minimum exposure that would result in an "excellent" print.
When the exposure was less the print quality was judged
inferior, but once that minimum exposure was given a further
increase in exposure had little effect on print quality over
a very wide range, many stops. Jones chose a speed point
near the minimum because the apparent grain was least and
sharpness greatest with minimum densities. Jones speed
point was such as to put the densities representing the
minimum shadow that was to have any detail on the toe of the
film curve where the gamma was about one third of the
"straight line" gamma. Kodak used this system internally as
"Kodak Speeds" for some time. It was adopted with some
changes, by the ASA about 1943. One problem was that the
ASA decided that since under exposure was a greater problem
than overexposure they would add a one stop safety factor so
published ASA speeds were about half the speed measured
using Jones method. Another problem was that measuring speed
by Jones method was difficult because it was based on the
gamma at two points on the film curve. About the mid 1950s
these problems led to a change by the ASA to the second DIN
system along with a couple of changes to it. The DIN system
measured a fixed density point. After considerable research
the ASA determined that when this speed was multiplied by a
small factor the result was nearly always identical to the
Jones speed but much easier to measure. The ASA adopted
this new method plus they dropped the safety factor. The
result is that all film speeds doubled overnight and a lot
of "magic" developers that guaranteed to increase film speed
disappeared.
The point of all this is that precise exposure is not
important for negative film provided its not to little.
Kodak adopted a system that is in some ways opposite of
the Zone system. What Kodak recommended was to expose to get
the information on the film and develop for a desired gamma
or contrast index, then adjust the contrast of the image by
choice of paper grade. Adams and Minor White worked out the
Zone system to insure adequate exposure after experiences
with badly exposed negatives that proved difficult to print.
I doubt if they were aware of the work of Jones, et.al. at
Kodak. One can work either way but there are some caveats:
one has to with the way the eye perceives images; we expect
a certain contrast in the mid-tones and tend to judge
overall images based on that. If you make an image low in
contrast in order to accommodate a wide brightness range in
the original image it may look flat and unnatural, the same
with increasing the contrast of a low-contrast image. I
think one has to try to get the mid-grays right and then, if
the highlights do not reproduce correctly use traditional
methods of burning and dodging, either by hand or with a
mask, to get them right. The real limit is in the range of
any reflection print that is viewed by ambient light. At the
widest, with glossy paper, this range is very substantially
less than can be recorded in a negative and generally less
than that in most original scenes. There really is no cure
for this other than manipulating the densities on the print
during printing to give the illusion of a full range of
brightness. Transparencies do not suffer so much from this
because they are generally illuminated in a way that can
produce highlight brightness well in excess of ambient
lighting.
Some additional notes: effective film speed is dependent
on development. The speed varies with the gamma to which the
film is developed and to some degree with the chemical
nature of the developer. The total range of variation with
different types of standard developer are about one stop
either way from a reference developer like D-76. The ISO
standard includes a chart to calculate the difference in
film speed when the degree of development is varied. The
standard specifies a brightness range for exposure and a
resulting density range. It does not specify a gamma
directly but does so indirectly through the above
specification. One reason for this is that many films do not
have linear density vs; exposure curves. The effective
contrast produced by the ISO speed method is about the right
contrast for contact printing or enlarging with a diffuse
light source. Printing using a condenser source may require
either lower contrast negatives or lower contrast paper. I
am not sure what effect, if any this has for scanning.
Of course, the Zone system also takes into account the
change in effective film speed with variations in
development to affect contrast.


--
Richard Knoppow
Los Angeles
WB6KBL
***@ix.netcom.com

[Chris Burck]

Richard,

Wow. Thank you so much for posting that.

--Chris

[Thor Legvold]

Wow Richard,

awesome post.

If I may paraphrase and simplify, current ISO/ASA/DIN ratings are close to the original minimum necessary exposure to ensure smallest grain and an excellent print (since they 1 stop “safety factor” was removed). Development is then chosen to arrive at a target gamma. Then one chooses paper to suit the contrast desired/envisioned.

Thank you so much for this information, you truly are a treasure trove!

Cheers,
Thor

Post by Richard Knoppow
Sent: Sunday, May 11, 2014 3:00 PM
Subject: [rollei_list] B&W film developing
Quick question for the people here on the list(s).
I’m working on getting my exposure and developmen dialed in, and have read some conflicting info.
"Expose for shadows, develop for highlights" seems to be the mantra.
This has already been discussed pretty fully but I will add something. The characteristics of film were investigated very thoroughly about eighty years ago by Loyd A. Jones of Kodak Labs. He wrote several papers most of which were published in the _Journal of the Franklin Institute_ at the time a well respected peer reviewed journal of the general sciences. Jones and his associates continued to publish research as late as the 1950s. His goal was to discover how film and paper render the tones of the original scene. Jones worked out a method of determining film speed. Speed is simply a way of being able to calculate the correct exposure when the brightness range of the scene is known and the transmission of light through the camera optical system is known. Jones investigated both the effects of varying the exposure and varying the development. What he found was that for a given development, that is when the film was processed to a specified mid-density gamma, and printed, there was a minimum exposure that would result in an "excellent" print. When the exposure was less the print quality was judged inferior, but once that minimum exposure was given a further increase in exposure had little effect on print quality over a very wide range, many stops. Jones chose a speed point near the minimum because the apparent grain was least and sharpness greatest with minimum densities. Jones speed point was such as to put the densities representing the minimum shadow that was to have any detail on the toe of the film curve where the gamma was about one third of the "straight line" gamma. Kodak used this system internally as "Kodak Speeds" for some time. It was adopted with some changes, by the ASA about 1943. One problem was that the ASA decided that since under exposure was a greater problem than overexposure they would add a one stop safety factor so published ASA speeds were about half the speed measured using Jones method. Another problem was that measuring speed by Jones method was difficult because it was based on the gamma at two points on the film curve. About the mid 1950s these problems led to a change by the ASA to the second DIN system along with a couple of changes to it. The DIN system measured a fixed density point. After considerable research the ASA determined that when this speed was multiplied by a small factor the result was nearly always identical to the Jones speed but much easier to measure. The ASA adopted this new method plus they dropped the safety factor. The result is that all film speeds doubled overnight and a lot of "magic" developers that guaranteed to increase film speed disappeared.
The point of all this is that precise exposure is not important for negative film provided its not to little.
Kodak adopted a system that is in some ways opposite of the Zone system. What Kodak recommended was to expose to get the information on the film and develop for a desired gamma or contrast index, then adjust the contrast of the image by choice of paper grade. Adams and Minor White worked out the Zone system to insure adequate exposure after experiences with badly exposed negatives that proved difficult to print. I doubt if they were aware of the work of Jones, et.al. at Kodak. One can work either way but there are some caveats: one has to with the way the eye perceives images; we expect a certain contrast in the mid-tones and tend to judge overall images based on that. If you make an image low in contrast in order to accommodate a wide brightness range in the original image it may look flat and unnatural, the same with increasing the contrast of a low-contrast image. I think one has to try to get the mid-grays right and then, if the highlights do not reproduce correctly use traditional methods of burning and dodging, either by hand or with a mask, to get them right. The real limit is in the range of any reflection print that is viewed by ambient light. At the widest, with glossy paper, this range is very substantially less than can be recorded in a negative and generally less than that in most original scenes. There really is no cure for this other than manipulating the densities on the print during printing to give the illusion of a full range of brightness. Transparencies do not suffer so much from this because they are generally illuminated in a way that can produce highlight brightness well in excess of ambient lighting.
Some additional notes: effective film speed is dependent on development. The speed varies with the gamma to which the film is developed and to some degree with the chemical nature of the developer. The total range of variation with different types of standard developer are about one stop either way from a reference developer like D-76. The ISO standard includes a chart to calculate the difference in film speed when the degree of development is varied. The standard specifies a brightness range for exposure and a resulting density range. It does not specify a gamma directly but does so indirectly through the above specification. One reason for this is that many films do not have linear density vs; exposure curves. The effective contrast produced by the ISO speed method is about the right contrast for contact printing or enlarging with a diffuse light source. Printing using a condenser source may require either lower contrast negatives or lower contrast paper. I am not sure what effect, if any this has for scanning.
Of course, the Zone system also takes into account the change in effective film speed with variations in development to affect contrast.
--
Richard Knoppow
Los Angeles
WB6KBL
---
Rollei List
- Online, searchable archives are available at
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[Eric Goldstein]

Post by Richard Knoppow

Post by Richard Knoppow
Kodak adopted a system that is in some ways opposite of the Zone

system. What Kodak recommended was to expose to get the information on the
film and develop for a desired gamma or contrast index, then adjust the
contrast of the image by choice of paper grade.

Richard, I don't think it's accurate to say what Kodak recommended was the
opposite of the Zone system. First and foremost, the zone system does not
recommend an exposure that would not result in getting the desired contrast
on the film, so in that sense they are both saying the same thing.

What always struct me as a contradiction to the statement "What Kodak
recommended was to expose to get the information on the film" was their
rating of consumer Tri-X as an ASA 400 film. In the strict sense of the
then-new ASA definition, it may have been, but I think most folks who shot
it regarded it and treated it as a 200 speed film exactly in the spirit of
exposing to get the information on the film.


Eric Goldstein

[Richard Knoppow]

----- Original Message -----
From: "Eric Goldstein" <***@gmail.com>
To: <***@freelists.org>
Sent: Monday, May 12, 2014 2:20 PM
Subject: [rollei_list] Re: B&W film developing

Post by Eric Goldstein

Post by Richard Knoppow

Post by Richard Knoppow
Kodak adopted a system that is in some ways opposite
of the Zone

system. What Kodak recommended was to expose to get the
information on the
film and develop for a desired gamma or contrast index,
then adjust the
contrast of the image by choice of paper grade.

Richard, I don't think it's accurate to say what Kodak
recommended was the
opposite of the Zone system. First and foremost, the zone
system does not
recommend an exposure that would not result in getting the
desired contrast
on the film, so in that sense they are both saying the
same thing.
What always struct me as a contradiction to the statement
"What Kodak
recommended was to expose to get the information on the
film" was their
rating of consumer Tri-X as an ASA 400 film. In the strict
sense of the
then-new ASA definition, it may have been, but I think
most folks who shot
it regarded it and treated it as a 200 speed film exactly
in the spirit of
exposing to get the information on the film.
Eric Goldstein

I think the difference is that the Kodak method was to
make the contrast adjustments in printing and the zone
system to make it in the negative. Actually you need to do
both and some scenes will need individual manipulation i.e.
burning and dodging, to get the image right. Either system
will get you there if you understand what you are doing.
Kodak was more interested in the mass market and minimal
manipulation of negatives. Print contrast via different
grades of paper can be done in mass production printing,
that is, photo-finishing.
The published speed for Tri-X or any other film is the
result of measuring it via some speed determining method. I
don't remember now how Jones specified exposure and density
ranges other than the speed point was where the toe gamma
was 1/3rd of the straight line gamma. There is a problem
with this since many films do not have a truly straight line
part of the curve. I think average gamma may have been used.
This measurement is a difficult one to make so the system
was abandoned when it was discovered that a minimum density
speed point with a correction would usually duplicate it.
Now, film is used in practice in ways different from the
way the film speed measurement uses it. Remember that Jones
found that an increase in exposure of many stops did no
damage to the tone rendition. So some increase in exposure
is perfectly satisfactory especially if one is not quite
certain about the accuracy of exposure of the camera
(usually they overexpose but not always). The main drawback
of increased exposure is increased printing time, not a big
deal. My own experience is that most films give better
images when given a bit more exposure than the box speed
suggests. There really is no such thing as "true" speed,
there is measured speed, that is measured using a controlled
system which is reproducible and there is whatever speed
results in the most pleasing prints. Maybe not always the
same. Actually L.A.Jones was trying for the latter in his
experiments. Unfortunately, the papers are scattered. Many
are in the Journal of the Franklin Institute but some are
elsewhere. There are references in Kenneth Meese books. Mine
are stashed away at the moment. Its possible some of this is
available from the web but I was never able to find any of
it and my copies of Jones papers are all from the public
library.
A note: When Meese created the Kodak Research Laboratory
he decided that the scientists at Kodak should publish their
scientific papers in established, peer-reviewed, journals
rather than in a house organ of some sort. This gave to
Kodak immediate credibility and status. However, it may make
some materials difficult to find because one must search
many journals. OTOH, it is very difficult to find some
company published journals. I found Meese's "Theory of the
Photographic Process" on Google books, well worth the
download even though chemical theory has changed
substantially since it was written. Meese has an extensive
bibliography of earlier research including Jones's work.
BTW, the spelling of Loyd is correct.
You may all be aware that Meese was working for and a
part owner of Wratten and Wainright in England. W&W had done
very considerable research into the use of dyes for
sensitizing film as well as for filters. George Eastman,
who had a tremendous respect for British scientists, was
already interested in developing a practical method of color
photography and wanted Meese partly to aid in that project.
Meese told Eastman that he was willing to go to Rochester
provided that Eastman would buy out Wratten and leave the
founders in charge of it. Eastman agreed and W&W became a
part of Kodak. Meese came to Rochester and set up the Kodak
Research Laboratories, one of the first corporate research
laboratories in the US. It was partly modeled on the
laboratories at General Electric which were the successors
to Edison's labs and the lab at Western Electric which later
became Bell Laboratories, . This was in 1912 which was a
very important time for industrial research, the labs at GE
and WE made discoveries at about this time that allowed
perfecting the vacuum tube and resulted in the enormous
growth of electronics. Meese was not able to devise a
practical color photography method for decades. Eventually
AGFA came up with the "modern" type of color, that is a
multi-layer film with built in color couplers so that it
could be developed directly into a color image. Kodak
eventually found another way to achieve this but it was not
fundamentally different from the AGFA method. Kodachrome,
despite its great success, was really only a stop-gap since
it required a very complex processing method well beyond
what could be done by most commercial labs let alone the
amateur photographer. Kodak had a couple of earlier
processes, both using names that got re-used later:
Kodacolor and Kodachrome. One was an additive process using
particles of dyed starch (or maybe a reseau, I don't
remember at the moment) the other a lenticular process which
was used for color motion pictures. Neither was very
satisfactory or very successful.
I have run way off the topic and will stop now.


--
Richard Knoppow
Los Angeles
WB6KBL
***@ix.netcom.com

[Marc James Small]

\Kodak eventually found another way to achieve this but it was not
fundamentally different from the AGFA method. Kodachrome, despite its
great success, was really only a stop-gap since it required a very
complex processing method well beyond what could be done by most
commercial labs let alone the amateur photographer. Kodak had a
Kodacolor and Kodachrome. One was an additive process using particles
of dyed starch (or maybe a reseau, I don't remember at the moment) the
other a lenticular process which was used for color motion pictures.
Neither was very satisfactory or very successful.

Kodak did study the late Prewar AGFA process but was barred by patent
law from using this. That constraint ended in 1941 with the German
declaration of war on the US. During both world wars, the warring
powers imposed Enemy Alien Property acts which effectively seized the
intellectual property rights of the opponents. AGFA -- a part of AF
Farbinindustrie -- had spent time and effort to expand their process so
the US, which briefly occupied the AGFA plant at Wolfen, seized the
process and made it a free grab for any US company and Kodak came to
the plate and took it. Thus was born Kodacolor. Yes, Kodak had a LOT
to do with it, but AGFA did the bulk of the work.

When the boundaries of occupation were established, the Wolfen plant
fell into the Soviet Zone but it seems that the US had completely
stripped the plant so that the Soviets learned nothing of significance.
In the end, the East Germans rebuilt the plant and marketed their wares
as ORWO -- Original Wolfen -- but ORWO only got into color after the
reunification of the Germanies, and that did not last long. But, damn!,
ORWO made some from schwarz-weisse films.

This is definitely on-topic as the only 120 chrome film available today
-- the Rolleiflex TLR's take 120 film --- are derived from this rivalry
between Kodak and AGFA.

Marc

[John Jensen]

Eastman Kodak claims Kodacolor print film was introduced in 1942.  Post 1945 I am sure Kodak 'improved' its film based on Agfa technology.

John


________________________________
From: Marc James Small <***@comcast.net>
To: ***@freelists.org
Sent: Monday, May 12, 2014 11:00 PM
Subject: [rollei_list] Re: B&W film developing

\Kodak eventually found another way to achieve this but it was not
fundamentally different from the AGFA method. Kodachrome, despite its
great success, was really only a stop-gap since it required a very
complex processing method well beyond what could be done by most
commercial labs let alone the amateur photographer.  Kodak had a
Kodacolor and Kodachrome. One was an additive process using particles
of dyed starch (or maybe a reseau, I don't remember at the moment) the
other a lenticular process which was used for color motion pictures.
Neither was very satisfactory or very successful.

Kodak did study the late Prewar AGFA process but was barred by patent
law from using this.  That constraint ended in 1941 with the German
declaration of war on the US.  During both world wars, the warring
powers imposed Enemy Alien Property acts which effectively seized the
intellectual property rights of the opponents.  AGFA -- a part of AF
Farbinindustrie -- had spent time and effort to expand their process so
the US, which briefly occupied the AGFA plant at Wolfen, seized the
process and made it a free grab for any US company  and Kodak came to
the plate and took it.  Thus was born Kodacolor.  Yes, Kodak had a LOT
to do with it, but AGFA did the bulk of the work.

When the boundaries of occupation were established, the Wolfen plant
fell into the Soviet Zone but it seems that the US had completely
stripped the plant so that the Soviets learned nothing of significance. 
In the end, the East Germans rebuilt the plant and marketed their wares
as ORWO -- Original Wolfen -- but ORWO only got into color after the
reunification of the Germanies, and that did not last long.  But, damn!,
ORWO made some from schwarz-weisse films.

This is definitely on-topic as the only 120 chrome film available today
-- the Rolleiflex TLR's take 120 film --- are derived from this rivalry
between Kodak and AGFA.

Marc


---
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[Marc James Small]

Post by John Jensen
Eastman Kodak claims Kodacolor print film was introduced in 1942.
Post 1945 I am sure Kodak 'improved' its film based on Agfa technology.

That makes sense, John. The Agfa process was in the public domain was
patented. If Kodak simply ' borrowed' the Agfa process in 1942, who
could complain? In 1943, the US passed its Alien Properties Act which
gave this some ex post facto legality. What the US wanted in 1945 were
the developments made since 1940, when Germany classified all such
industrial processes, and 1945, when the War ended.

Marc

[Chris Burck]

Fascinating. Can't help but wonder what would have been, had Kodak been
unable to breach Agfa's patents.

Post by Richard Knoppow
Sent: Monday, May 12, 2014 2:20 PM
Subject: [rollei_list] Re: B&W film developing

Post by Eric Goldstein

Post by Richard Knoppow

Kodak adopted a system that is in some ways opposite > of the Zone

system. What Kodak recommended was to expose to get the information on the
film and develop for a desired gamma or contrast index, then adjust the
contrast of the image by choice of paper grade.

Richard, I don't think it's accurate to say what Kodak recommended was the
opposite of the Zone system. First and foremost, the zone system does not
recommend an exposure that would not result in getting the desired contrast
on the film, so in that sense they are both saying the same thing.
What always struct me as a contradiction to the statement "What Kodak
recommended was to expose to get the information on the film" was their
rating of consumer Tri-X as an ASA 400 film. In the strict sense of the
then-new ASA definition, it may have been, but I think most folks who shot
it regarded it and treated it as a 200 speed film exactly in the spirit of
exposing to get the information on the film.
Eric Goldstein

I think the difference is that the Kodak method was to make the
contrast adjustments in printing and the zone system to make it in the
negative. Actually you need to do both and some scenes will need individual
manipulation i.e. burning and dodging, to get the image right. Either
system will get you there if you understand what you are doing. Kodak was
more interested in the mass market and minimal manipulation of negatives.
Print contrast via different grades of paper can be done in mass production
printing, that is, photo-finishing.
The published speed for Tri-X or any other film is the result of
measuring it via some speed determining method. I don't remember now how
Jones specified exposure and density ranges other than the speed point was
where the toe gamma was 1/3rd of the straight line gamma. There is a
problem with this since many films do not have a truly straight line part
of the curve. I think average gamma may have been used. This measurement is
a difficult one to make so the system was abandoned when it was discovered
that a minimum density speed point with a correction would usually
duplicate it. Now, film is used in practice in ways different from the way
the film speed measurement uses it. Remember that Jones found that an
increase in exposure of many stops did no damage to the tone rendition. So
some increase in exposure is perfectly satisfactory especially if one is
not quite certain about the accuracy of exposure of the camera (usually
they overexpose but not always). The main drawback of increased exposure
is increased printing time, not a big deal. My own experience is that most
films give better images when given a bit more exposure than the box speed
suggests. There really is no such thing as "true" speed, there is measured
speed, that is measured using a controlled system which is reproducible and
there is whatever speed results in the most pleasing prints. Maybe not
always the same. Actually L.A.Jones was trying for the latter in his
experiments. Unfortunately, the papers are scattered. Many are in the
Journal of the Franklin Institute but some are elsewhere. There are
references in Kenneth Meese books. Mine are stashed away at the moment. Its
possible some of this is available from the web but I was never able to
find any of it and my copies of Jones papers are all from the public
library.
A note: When Meese created the Kodak Research Laboratory he decided
that the scientists at Kodak should publish their scientific papers in
established, peer-reviewed, journals rather than in a house organ of some
sort. This gave to Kodak immediate credibility and status. However, it may
make some materials difficult to find because one must search many
journals. OTOH, it is very difficult to find some company published
journals. I found Meese's "Theory of the Photographic Process" on Google
books, well worth the download even though chemical theory has changed
substantially since it was written. Meese has an extensive bibliography of
earlier research including Jones's work. BTW, the spelling of Loyd is
correct.
You may all be aware that Meese was working for and a part owner of
Wratten and Wainright in England. W&W had done very considerable research
into the use of dyes for sensitizing film as well as for filters. George
Eastman, who had a tremendous respect for British scientists, was already
interested in developing a practical method of color photography and wanted
Meese partly to aid in that project. Meese told Eastman that he was willing
to go to Rochester provided that Eastman would buy out Wratten and leave
the founders in charge of it. Eastman agreed and W&W became a part of
Kodak. Meese came to Rochester and set up the Kodak Research Laboratories,
one of the first corporate research laboratories in the US. It was partly
modeled on the laboratories at General Electric which were the successors
to Edison's labs and the lab at Western Electric which later became Bell
Laboratories, . This was in 1912 which was a very important time for
industrial research, the labs at GE and WE made discoveries at about this
time that allowed perfecting the vacuum tube and resulted in the enormous
growth of electronics. Meese was not able to devise a practical color
photography method for decades. Eventually AGFA came up with the "modern"
type of color, that is a multi-layer film with built in color couplers so
that it could be developed directly into a color image. Kodak eventually
found another way to achieve this but it was not fundamentally different
from the AGFA method. Kodachrome, despite its great success, was really
only a stop-gap since it required a very complex processing method well
beyond what could be done by most commercial labs let alone the amateur
photographer. Kodak had a couple of earlier processes, both using names
that got re-used later: Kodacolor and Kodachrome. One was an additive
process using particles of dyed starch (or maybe a reseau, I don't remember
at the moment) the other a lenticular process which was used for color
motion pictures. Neither was very satisfactory or very successful.
I have run way off the topic and will stop now.
--
Richard Knoppow
Los Angeles
WB6KBL
---
Rollei List
subject field OR by logging into www.freelists.org
the subject field OR by logging into www.freelists.org
- Online, searchable archives are available at
http://www.freelists.org/archives/rollei_list

[Eric Goldstein]

I think the difference is that the Kodak method was to make the
contrast adjustments in printing and the zone system to make it in the
negative.



Hi Richard - the Zone system makes contrast adjustments in the print as
well, though the idea is to do as much of the compensation with the
negative as is possible.


Eric Goldstein

[Don Williams]

Post by Eric Goldstein
Hi Richard - the Zone system makes contrast adjustments in the print
as well, though the idea is to do as much of the compensation with
the negative as is possible.
Eric Goldstein

Well, I think we are all being left in the dust by our kids and grand kids.

One of my grand kids posted an extended range picture made
automatically by his smart phone. Apparently it takes 3 exposures at
different levels and combines them. Really great range. I was
really impressed.

(I think one name for the process is High Dynamic Range, HDR, but
I've seen several discussions calling the process by several different names.)

DAW

[Eric Goldstein]

Don, I promise you I am not left in the dust by the talents of my kids and
grandkids... can you think of why I can be so sure?

If your shots pale in comparison to HDR cell phone shots, ok. Many of us
were making HDR images from a couple of film negatives before anyone
conceived of the notion that there could be digital HDR images combined
through automation.

I've looked at many many instagram, flickr, and similar sites that feature
the cell phone shots of famous/professional shooters, and they overwhelming
majority look, to my eye, like cell phone snap shots, unless the moment is
truly exceptional and then no one cares about anything but the content.

And yes those shooters are someone's kids and grandkids... ;-)


Eric Goldstein

Post by Eric Goldstein
Hi Richard - the Zone system makes contrast adjustments in the print as
well, though the idea is to do as much of the compensation with the
negative as is possible.
Eric Goldstein
Well, I think we are all being left in the dust by our kids and grand kids.
One of my grand kids posted an extended range picture made automatically
by his smart phone. Apparently it takes 3 exposures at different levels
and combines them. Really great range. I was really impressed.
(I think one name for the process is High Dynamic Range, HDR, but I've
seen several discussions calling the process by several different names.)
DAW

[Richard Knoppow]

----- Original Message -----
From: "Chris Burck" <***@gmail.com>
To: <***@freelists.org>
Sent: Tuesday, May 13, 2014 12:58 PM
Subject: [rollei_list] Re: B&W film developing

Post by Chris Burck
Fascinating. Can't help but wonder what would have been,
had Kodak been
unable to breach Agfa's patents.
On May 12, 2014 11:52 PM, "Richard Knoppow"

My reference books are hiding in storage. Both AGFA and
Kodak were working on color film from early on. Both had
come up with additive films using a dyed starch reseau and a
lenticular film. Both had problems especially in the area of
duplicating.
The main difference between the AGFA and Kodak
multi-layer film was the method used to keep the couplers
and resulting dye particals from wandering in the emulsion.
AGFA attached the couplers to very long chain molecules that
were too big to move in the gelatin. Kodak encapsulated the
couplers in tiny oil droplets that served the same purpose.
The two types of film require somewhat different methods of
processing. The oil droplet film requires the color
developer to have a solvent in it capable of penetrating the
droplets. Both types of film were made for a few decades but
eventually the Kodak type won out and is the type which
currently survives. The method of sequestering the coupler
is the same for both negative and reversal films. From what
I can find on the web it appears that both Kodak and AGFA
had working films using incorporated couplers by the mid
1930s but Kodak evidently was not satisfied with theirs and
held off producing it for a few years. Note that Kodachrome
does not have incorporated couplers; rather the couplers are
in the reversal developers. Note developers plural because
there are three of them. The development process is
extremely complex but resulted in very good color quality.
None of these films had any sort of masking. Kodak devised
color masking about the late 1940s by means of colored
couplers. The purpose of the masking is to compensate for
spurious transmission by the dyes in order to improve both
color purity and accuracy. Masking originally could be used
only in color negative films and the colored coupler method
is still confined to them but another method of compensating
for the dyes was found by allowing interlayer reaction so
that the production of dye in one layer results in a
reduction of dye in the adjacent layer. This method can be
applied to either negative or reversal films.
Someone mentioned that some digital cameras make three
bracked exposures to extend the dynamic range. In fact, many
films, both B&W and color have two or three layers of
emulsion, color films have them for each color, of differing
speed, for the same purpose, that is extending the dynamic
range.
BTW, I have heard the story before that Kodak was able
to use AGFA patents during WW-2 in order to make color
aerial film. I think if this is true its because the AGFA
film was ready for production while Kodak was still
researching. At the time we entered WW-2 as a combatent AGFA
was well established in the U.S. It had bought Ansco in 1926
and had holdings of DuPont chemical and other U.S.
companies. See the history of I.G.Farben for more and for
the Nazi connections of these companies.


--
Richard Knoppow
Los Angeles
WB6KBL
***@ix.netcom.com