Orthochromatic film

thuggins said:

A search for orthochromatic film brought up a bunch of "this product no longer available". Is this just completely gone?

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https://www.macodirect.de/en/film/black-white-films/1841/rollei-ortho-25-roll-film-120

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I use Kodak Ektascan B/RA X-Ray film in my 8x10 camera to make negatives for platinum printing with excellent results. Develop in Rodinal 1:100.

I have also used the Ilford Ortho Plus in 8x10 for the same purpose and I get similar results for this application. The X-Ray film at 80 cents per sheet vs. $5 a sheet for the Ilford film is a big difference when there is no reason not to use the X-Ray film in my application. I have used the Ilford Ortho Plus to make b/w positives that I use in gumoil printing and it works very well for this scenario.

Jim Noel said:

That is your opinion. There are too many photographers doing beautiful work with x-ray film to accept such a statement. At $0.35 to $0.80 per 8x10 sheet it is well worth doing the necessary experimentation to make this film work in the manner desired.

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With the right filtration films can produce the same effect as ortho films. For best results use a minus red (cyan) filter. Green filters are also good but produce results not quite like ortho. Do not use a blue filter as it will not work. Remember that ortho films see into the green and yellow portions of the visible spectrum. Blue would entirely block these portions giving the effect of an emulsion that is not color sensitized at all.

Just an augmentation of Gerald's post above: Yes, a blue filter that passes no green will not give an orthochromatic rendering (e.g., Wratten #47), but instead give you a rendering like early blue-sensitive film. However, blue-looking color correction filters, originally designed for adapting daylight film to tungsten light sources, such as the 80A I mentioned above, do pass a lot of green and even some red, despite their blue appearance. If you want more light in the green-red part of the spectrum, there are weaker filters in the series, 80B and 80C, which pass a bit more in that area. The real "orthochromatic filter" is the cyan-colored Wratten #44A (or the #44 which has a slightly broader transmission spectrum). These latter, unfortunately, are only available in gels. It's likely that cyan CC filters would also work if you found the appropriate strength. I haven't experimented with these.

Best,

Doremus

analog65 said:

The X-Ray film at 80 cents per sheet vs. $5 a sheet for the Ilford film is a big difference when there is no reason not to use the X-Ray film in my application.

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The auction site is showing x-ray film for as low as $.29 a sheet. Thats a hell of a deal.