Developing ultra low ISO films for direct duplicating

[O z]

This is more due to the base material than to the sensitivity of the emulsion. There are a number of panchromatic and even super-panchromatic (extended red sensitivity) films with the same concern.

Noted. Thank you!

 

[koraks]

I can shoot a test roll using green subjects and share better results soon.

It'll be more useful to shoot a color checker like @Donald Qualls suggested. Green subjects are a little tricky because it depends on how the green is built up. Green can be something that reflects light in a fairly narrow 520-550nm wavelength band, or it can be a composite of colors that reflects a broad range of wavelengths ranging from UV up to 550nm or so. The implication is that some typically green subjects, such as green plants/leaves, actually reflect a decent amount of blue light and thus will appear relatively light-colored on a blue-sensitive recording. This isn't because the blue-sensitive medium is also sensitive to green, but because there's a decent amount of blue light being reflected by the object. With man-made objects the situation is even more tricky because many man-made pigments have discontinuous spectra.

If you have a prism, you could create a rainbow effect (use sunlight if possible, and otherwise tungsten; not CFL or LED) and photograph that.

 

[O z]

Or someone could just shoot a color chart so you can't argue with the results...

I missed this comment earlier. Thank you! Will do and report back.

 

[O z]

It'll be more useful to shoot a color checker like @Donald Qualls suggested. Green subjects are a little tricky because it depends on how the green is built up. Green can be something that reflects light in a fairly narrow 520-550nm wavelength band, or it can be a composite of colors that reflects a broad range of wavelengths ranging from UV up to 550nm or so. The implication is that some typically green subjects, such as green plants/leaves, actually reflect a decent amount of blue light and thus will appear relatively light-colored on a blue-sensitive recording. This isn't because the blue-sensitive medium is also sensitive to green, but because there's a decent amount of blue light being reflected by the object. With man-made objects the situation is even more tricky because many man-made pigments have discontinuous spectra.

If you have a prism, you could create a rainbow effect (use sunlight if possible, and otherwise tungsten; not CFL or LED) and photograph that.

Makes perfect sense. Thank you! I don’t have a color chart or a prism at the moment but I’ll try to get either one. Would printing out a color chart be a viable alternative (for the purpose of this test) to commercially available color charts?

 

[koraks]

Would printing out a color chart be a viable alternative (for the purpose of this test) to commercially available color charts?

It's tricky. The problem if you digitally print a color chart, it'll most likely be made up of yellow, magenta, cyan and black pigment. What the film will see, depends on the pigments involved. In principle, a pure yellow patch printed with only the yellow ink of an inkjet or laser printer should show up relatively dark on a blue-sensitive film. However, again, it depends on the pigment involved. Moreover, there's a problem with printing this way as it's usually not possible or very difficult to print with a single ink channel only. It generally requires special software tools to do so. Sometimes, there are test pages you can print with a printer (e.g. head alignment charts etc.) that use single channels at a time. You could try and use something along those lines.

So there are several caveats to doing this. Yes, it's possible, but setting up the experiment correctly and the correctly interpreting the results is a little more tricky than it seems at first glance.

 

[O z]

It's tricky. The problem if you digitally print a color chart, it'll most likely be made up of yellow, magenta, cyan and black pigment. What the film will see, depends on the pigments involved. In principle, a pure yellow patch printed with only the yellow ink of an inkjet or laser printer should show up relatively dark on a blue-sensitive film. However, again, it depends on the pigment involved. Moreover, there's a problem with printing this way as it's usually not possible or very difficult to print with a single ink channel only. It generally requires special software tools to do so. Sometimes, there are test pages you can print with a printer (e.g. head alignment charts etc.) that use single channels at a time. You could try and use something along those lines.

So there are several caveats to doing this. Yes, it's possible, but setting up the experiment correctly and the correctly interpreting the results is a little more tricky than it seems at first glance.

Noted. Thank you!
Printing this way would to be too complicated for what I have available. Will see if I can get a professional color card like the ones used in color correction, finding a prism might be easier and less expensive.

I’ll keep reading and testing and will report back soon. Thank you all for your much appreciated help, time and patience!

 

[MarkS]

Someone out here must have a copy of the second edition of (laser) Bob Shanebrook's fine book "Making Kodak Film". The copy I saw (I don't own one) listed an enormous number of emulsions that Kodak made, and there is likely to some information on the 2612 in question here. Best to go to the source!
I've used many Kodak films, for many purposes, during my career but have never heard of that one.

 

[Augustus Caesar]

I am posting here question about possibilities for increasing ISO of those emulsions in developing process and kindly asking members to share their experiences in order to have it on one place.
Thanks.

Forget it. This film is high-contrast.

 

[koraks]

Someone out here must have a copy of the second edition of (laser) Bob Shanebrook's fine book "Making Kodak Film". The copy I saw (I don't own one) listed an enormous number of emulsions that Kodak made, and there is likely to some information on the 2612 in question here. Best to go to the source!

Maybe @laser (Bob Shanebrook) could comment.

 

[Ben Hutcherson]

Only that particular film. Don't assume it's representative for your particular film.

Not to side track too much, but doesn't even X-ray film come in blue sensitive and green sensitive? I'm GUESSING a green sensitive form would also be blue sensitive, but I haven't really looked that closely at sensitivity of X-ray film...

 

[lamerko]

Since X-rays are below the UV range, it makes no sense for the film to be sensitive to green...

 

[Ben Hutcherson]

Since X-rays are below the UV range, it makes no sense for the film to be sensitive to green...

As per my understanding, X-ray film is often used next to a phosphorescent screen. The phosphors could be either green or blue, thus the need for green sensitivity.

Ebay is awash with very affordable sensitometers that some have adapted for photo film, but the most available ones were intended for use with X-ray film. Every one I've looked at can be set for either blue or green light.

 

[Donald Qualls]

Not to side track too much, but doesn't even X-ray film come in blue sensitive and green sensitive? I'm GUESSING a green sensitive form would also be blue sensitive, but I haven't really looked that closely at sensitivity of X-ray film...

Yes, "green sensitive" x-ray film is what photographers would call orthochromatic -- it's sensitive from UV into green (how far into green may differ, but as noted above, it's for a phosphor screen to allow much lower x-ray dose than direct exposure).

 

[koraks]

Not to side track too much, but doesn't even X-ray film come in blue sensitive and green sensitive? I'm GUESSING a green sensitive form would also be blue sensitive, but I haven't really looked that closely at sensitivity of X-ray film...

Yes, that's correct.

As per my understanding, X-ray film is often used next to a phosphorescent screen. The phosphors could be either green or blue, thus the need for green sensitivity.

That's also correct; the spectral sensitization has no relationship with the actual wavelength of the xrays, which indeed is orders of magnitude smaller. But that's irrelevant because of the phosphor screen that indeed does the 'conversion' from the xrays to visible light, which is then recorded by the film.

 

[O z]

Someone out here must have a copy of the second edition of (laser) Bob Shanebrook's fine book "Making Kodak Film". The copy I saw (I don't own one) listed an enormous number of emulsions that Kodak made, and there is likely to some information on the 2612 in question here. Best to go to the source!
I've used many Kodak films, for many purposes, during my career but have never heard of that one.

Thank you very much for the recommendation and apologies for the late response! I found Bob Shanebrook’s website and read a few reviews of his seemingly excellent book. Unfortunately, It’d be a bit expensive for me to purchase a copy at the moment, giving the crazy currency exchange rate, and that I’m trying to practice on a tight budget.

 

[O z]

Regarding “Kodak 2612” and whether it is sensitive to green or not: I couldn’t find a reasonably priced color chart yet but I had this color labeled remote control for a strip of RGB LEDs, and I couldn’t help but trying to see if it would serve as a quick (even if less accurate) alternative in determining if the film is sensitive to green or not.
I shot a test roll using it and several other multi-colored objects from around the house and I got the scans today. If the attached scan is not completely off, I think the film might be partly sensitive to green. What do you think? I have more scans from this roll to share if needed.

Unedited scan (compressed using WhatsApp) Kodak 2612, shot at EI 3, Developed in Rodinal 1+100 for 18 minutes @ 20°C

iPhone photo of the frame for color reference
———

A section of the negative to show the issue of fog around the perforations, associated with developing in Rodinal for 18 minutes.
I managed to decrease the fog to almost nothing in later tests by estimating ISO at 12, shooting in broad daylight and reducing development time to 17 minutes, as shown below:

 

[koraks]

I shot a test roll using it and several other multi-colored objects from around the house and I got the scans today. If the attached scan is not completely off, I think the film might be partly sensitive to green. What do you think?

I think your experiment has a fatal flaw that renders it virtually useless. The 'green' you see on printed media (including your LED remote) is composed of (mostly) cyan and yellow ink. The reflection spectrum of the cyan ink can be sufficiently broad as to give the impression that the film 'sees' green, while in fact it doesn't. Note also how the halftone dots on the green buttons show up:

If anything, this demonstrates that the film images this mixed green color (which really is only green to the human eye, not an actual green like e.g. chlorophyll) quite differently from how it appears to your eyes.

So no, the experiment doesn't show what you think it does, and in fact leans more in the opposite direction.

You can fairly cheaply get a prism on e.g. AliExpress, assuming they will ship to Egypt. Or any other outlet of mass-produced Chinese stuff.

 

[O z]

I think your experiment has a fatal flaw that renders it virtually useless. The 'green' you see on printed media (including your LED remote) is composed of (mostly) cyan and yellow ink. The reflection spectrum of the cyan ink can be sufficiently broad as to give the impression that the film 'sees' green, while in fact it doesn't. Note also how the halftone dots on the green buttons show up:
View attachment 389490
If anything, this demonstrates that the film images this mixed green color (which really is only green to the human eye, not an actual green like e.g. chlorophyll) quite differently from how it appears to your eyes.

So no, the experiment doesn't show what you think it does, and in fact leans more in the opposite direction.

You can fairly cheaply get a prism on e.g. AliExpress, assuming they will ship to Egypt. Or any other outlet of mass-produced Chinese stuff.

Thank you! Noted. Will keep looking for a prism and repeat the test when I get one.

I’d like to keep sharing results from my experiments with “Kodak 2612” if anyone’s interested or thinks it might be worth sharing. If so, should I just keep posting here or would it be better to start a separate thread?

 

[koraks]

I'm sure many will follow your progress with interest. Perhaps because it's a specific type of film you're now assessing, it makes sense to make a dedicated thread for it. But if you prefer to update this thread, that's fine, too.

 

[lamerko]

I am extremely surprised by the clearing of the base fog with a reduction in time from 18 to 17 minutes. Do you apply any temperature control and have you measured how many degrees it is after the end of the process?

 

[O z]

I am extremely surprised by the clearing of the base fog with a reduction in time from 18 to 17 minutes. Do you apply any temperature control and have you measured how many degrees it is after the end of the process?

Me too. I’ll have to wait for the scans of this roll to see if the photos are underdeveloped or not, but negatives look okay to my eye despite exposing at EI 12.
I don’t usually do temperature control but I start developing at 20°C and by the end (when I measured) it was 22:23°C maximum.

 

[O z]

I'm sure many will follow your progress with interest. Perhaps because it's a specific type of film you're now assessing, it makes sense to make a dedicated thread for it. But if you prefer to update this thread, that's fine, too.

That’s encouraging! Thank you.
Will keep at it and keep you posted. Appreciate the support!

 

[Yezishu]

Let me report a result of Kodak 2468 direct positive film for reference.
Metered at 20 ISO and 1/60s, then shooting at 1s (~0.33 ISO, some errors here have been corrected). Developed in PC-TEA (Dimezone S and Ascorbic Acid, 1:20), agitated for the first 5 minutes, then stand for 10 minutes at 20°C.

I believe the pics shows that its latitude is very low (not surprisingly), making it unsuitable for high-contrast scenes, but the resolution is also extremely high. The number of effective pixels may be between 60 million and 200 million, I need Pixel Shift Multi-shooting to fully capture the details.

 

[koraks]

Great examples, thanks for posting those @Yezishu. I googled a bit and found some data for 2468 here: https://www.shopscan.com.br/wp-content/uploads/2011/02/D-32.pdf

Note its high UV-sensitivity and otherwise somewhat fluctuating orthochromatic profile. This seems to be reflected in the sky of the second image, that struggles to make good contrast with the buildings in the background.
Looks pretty steep, too:

So again very much in line with what you report.

 

[O z]

Following up on my experiments with Kodak 2612 and Rodinal:
———
I found a glass crystal that breaks down sunlight in a somewhat similar way to a prism, but I’m not sure if that’d be good enough to determine whether the film is sensitive to green or not, i decided to use it anyway until I find an optical-glass prism. I located a shop that had it but it was currently out of stock so, i'm waiting for them to restock.
Meanwile, I shot a bracketed test roll between EI: 01 and EI: 12, as a means to re-estimate the optimum ISO of the film in daylight that works with the 16.5 minutes of development that proved to decrease the fog to a minimum.

Annotated shot of the negative to show density difference and fog level
Unedited scans of the entire roll can be found here:

00000219 - Google Drive

drive.google.com

While the test might not be decisive in terms of green sensitivity but It seems to me that both EI: 1.5 and EI: 3 gave usable results in terms of achieving a better tonal range.


iPhone shot for reference


EI: 03


EI: 1.5
———

iPhone shot for reference


EI: 03


EI: 1.5