Can you recommend an ortho film for use in-camera?

Interesting - direct reversal...copy film...makes sense...

I guess I'll just give it a try.

Thanks

Murray

Look at the curves again. It is definitely not a direct reversal film. I have some and use it for internegatives. The curve posted shows reflection density against transmission density on the film negative. IOW, it shows a curve for copying positives, not negatives. Kodak did have a direct reversal film named SO-132, but has been gone for a long time.

Donald Miller said:

An example by illustration would be to take popcorn and suppose that by failing to add salt one adds sugar...we all know that does not happen.

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???

By using a minus red filter only the short wave lengths of the visible spectrum, the blue and green portions, will reach the film. Those colors will appear lighter while the other colors of the spectrum, the longer wavelength yellows and, oranges will appear darker with red showing as black. Of course, how well this works depends on how good the filter is in cutting off the longer wavelengths. No filter is perfect but this should produce a very good approximation of the ortho look.

Thanks all.

Gerald Koch said:

???

By using a minus red filter only the short wave lengths of the visible spectrum, the blue and green portions, will reach the film. Those colors will appear lighter while the other colors of the spectrum, the longer wavelength yellows and, oranges will appear darker with red showing as black. Of course, how well this works depends on how good the filter is in cutting off the longer wavelengths. No filter is perfect but this should produce a very good approximation of the ortho look.

Click to expand...

My reponse was directed to someone who contended that the converse of what you stated was possible.

My position is that one can not filter and duplicate a true panchromatic material from an orthochromatic material. A great deal depends on the spectral characteristics of the emulsion.

Orthochromatic materials are sensitive to the blue spectrum and may have very little if any sensitivity to red. So therefore by shutting of the blue spectrum with a minus blue filter does not necessarily equate to making an orthochromatic material into a panchormatic material. If the sensitivity to the red spectrum is not present as a characteristic of the emulsion, no amount of filtering, regardless of the filter used is going to create emulsion sensitivity that does not exist.

Thus I stand with my earlier position that removal of something does not equate to the creation or the addition of something that is not present as an emulsion characteristic.

As we both know, panchromatic emulsions have a more global sensitivity then orthochromatic materials. As I stated originally that was not what I was addressing. My original statement addressed the mistaken belief that one could filter orthochromatic materials and have them replicate a panchromatic emulsion. Since orthochromatic materials have a limited spectral response, there is no amount of filtering that will effect a spectral change to the extent that they replicate panchromatic materials.

For those that may be interested, I direct them to the chart of spectral response found it Adams "The Negative" This chart may be found on page 22.

Donald,

"My position is that one can not filter and duplicate a true panchromatic material from an orthochromatic material.

...

Thus I stand with my earlier position that removal of something does not equate to the creation or the addition of something that is not present as an emulsion characteristic.
"

I don't think that anyone would argue with that, or with the general principle that filters cannot add spectral sensitivity to a film.


"One can not duplicate an orthochromatic emulsion or in any way come close to it by filtering a panchromatic film.'

Going from panchro to ortho doesn't involve the addition of any sensitivity - it only involves subtraction. Filtering a pan film with a cyan filter may not exactly recreate the characteristics of ortho film, but it will come close.

Best,
Helen

Donald, I'm sure it was just a mental lapse.

But what you said in your original post was that there is "no way to filter a panchromatic film to make it mimic an orthochromatic film".

So you are right - now. You were wrong - then.