Quick question: Removing dye on isochromatic film

Hi everyone,
Currently I'm working on a photo shoot and we're trying to match up certain hues of make-up/wardrobe for a particular era look. I am using Kodak 5366 (Blue sensitive/EI 6/Processing as a neg) And, after much testing, we just have to raise the sensitivity a bit more towards the green. The film has a water-soluble yellow dye and I was wondering if I would expect higher green sensitivity if I were to remove the dye and then drying it out overnight in the darkroom. I know a simple test would do, but like always, I like to see what my fellow APUG-ers recommend, not mention saving me some time just in case what I'm proposing is futile

Also, should I add photo-flo when I'm washing the dye off? Any suggestions/comments would be greatly appreciated.

Thanks, Yuri

What is a isochromatic film?

I guess you mean spectrally non-sensitized.


The small green sensitivity would not be hampered by a yellow dye anyway. If it was part of the emulsion in first case.

1 - The film as per datasheet
http://motion.kodak.com/motion/uploadedFiles/h15366(1).pdf
is a blue-sensitive film. Sensitivity in the green (550nm) is about a factor 100 below sensitivity in the blue (450nm)
2 - The yellow dye has a stated purpose "to provide very high acutance"
3 - Removing the yellow dye, if any effect, would increase the blue sensitivity relative to green (where it is small) and relative to red (where it is nil). Contrary ro your stated goal "I would expect higher green sensitivity"
4 - If you want to achieve "a particular era look" I'd say your best bet is (through iterated tests) to use a panchromatic film with TBD filters.

What does TBD mean? I assume something about blue density.

An isochromatic film has a red sensitivity between an orthochromatic film and a panchromatic one. Therefore 5366 is NOT an isochromatic film. It is intended for printing where color sensitivity is not important. If you look at the spectral curve on the data sheet you will see that green sensitivity is approximately 15 times less than the blue sensitivity.

Trying to duplicate the "look" of a particular era has been discussed before on APUG. A particular look has more to do with things as subject matter, clothing, lighting, background, props, etc rather than with the use of a particular film. You are probably better off using a panchromatic film in conjunction with the right filter.

bernard_L said:

1 - The film as per datasheet
http://motion.kodak.com/motion/uploadedFiles/h15366(1).pdf
is a blue-sensitive film. Sensitivity in the green (550nm) is about a factor 100 below sensitivity in the blue (450nm)
2 - The yellow dye has a stated purpose "to provide very high acutance"
3 - Removing the yellow dye, if any effect, would increase the blue sensitivity relative to green (where it is small) and relative to red (where it is nil). Contrary ro your stated goal "I would expect higher green sensitivity"
4 - If you want to achieve "a particular era look" I'd say your best bet is (through iterated tests) to use a panchromatic film with TBD filters.

Click to expand...

Now I see. It makes sense; my thinking was backwards...<blushing emoticon here>.

Gerald C Koch said:

An isochromatic film has a red sensitivity between an orthochromatic film and a panchromatic one. Therefore 5366 is NOT an isochromatic film. It is intended for printing where color sensitivity is not important. If you look at the spectral curve on the data sheet you will see that green sensitivity is approximately 15 times less than the blue sensitivity.

Trying to duplicate the "look" of a particular era has been discussed before on APUG. A particular look has more to do with things as subject matter, clothing, lighting, background, props, etc rather than with the use of a particular film. You are probably better off using a panchromatic film in conjunction with the right filter.

Click to expand...

Thanks Gerald: upon looking at the data sheet I see what is meant. Somehow I always thought that 'isochromatic' followed the dictionary meaning ["one color" (any color)] but I see I was mistaken. In terms of 'particular look' we're going for turn-of-the century. We have everything down: wardrobe, location and even my make-up artist researched the make-up used at the time, well, at least the non-toxic ones, anyway.
Our goal is almost met, but seeing how it's just a minor detail (in this case a particular shade of green on dress we want to come out lighter) I'll scratch the 5366 and use pan. Only reason I pushed the aforementioned film was because I have excess of 3000' begging to be used in my cold-store.

I'm glad I asked, if I had not done so I probably would have wasted a lot of time until I realised my lapse in reason.

Gerald C Koch said:

An isochromatic film has a red sensitivity between an orthochromatic film and a panchromatic one.

Click to expand...

There are several definitions of this term:

-) ortho-panchromatic (as you just described)

-) orthochromatic

-) having equal sensitivity over the complete sensibility spectrum

-) refering to the same wavelenghts


Thus this term better should be avoided.

Superpanchromatic - sensitive to all colors of the spectrum, plus (usually) extended red sensitivity into the near-infrared.
Panchromatic - most modern B&W films are this type.
Orthopanchromatic - Sensitive to green and blue, some sensitivity to red but not as much.
Orthochromatic - sensitive to green and blue, but not red.
There was another kind of film whose name I don't remember. It was sensitive to blue/purple colors only.

If you want reduced sensitivity to green, shoot through a magenta filter, which will pass blue and red but less green. If you want no green sensitivity, shoot with a "minus green" filter (deep magenta in color). If you want the orthochromatic look with panchromatic film, shoot with a "minus red" filter (cyan in color) as it will pass green and blue but not red. For orthopanchromatic, shoot with a cyan filter that's lighter in color than a minus red filter.

Does this help?

AgX said:

-) having equal sensitivity over the complete sensibility spectrum

Click to expand...

This may be the best description of the name. The problem with some orthochromatic films is they have a higher blue sensitivity than desired. This causes blues to be too light. Isochromatic films solve this problem by reducing the sensitivity to blue light producing a better representation of colors. They also add some added red sensitivity. Kodak Verichrome was an early representative of an isochromatic film hence the use of the term veri derived from the Latin word for truth. So "Verichrome" means true color or a better gray scale representation of the scene.

thanks for the info, between everyone's posts I filled up a page of notes in my notes (I'm kinda' OCD with notes) I have a few stocks to play with, including ADOX ortho 25.
In hindsight I wished in school we were taught more about film spectral sensitivity, all we were taught were the basics: [ortho/pan] since the majority of stocks I know and have used are cine and color at that, I haven't much experience with B&W still films that are/were available.