Filter Factors for Efke 100 8x10"

[holmburgers]

A fellow apuggian generously sent me a box of Efke 8x10" 100 speed b&w film.

I'm intending to use it for making color separations, both in camera and under the enlarger. The thing of it is, I'm not able to find any filter factor recommendations.

Specifically, I'm going to use the hard-cutting wratten color sep filters, like 29, 47b and so forth.

Kodak has nice charts for Tmax and Tri-x showing the filter factors and the recommended color sep filters, but alas, I fear nothing will exist for Efke.

However, if you've got any suggestions or tips, I'm all ears. I was thinking to apply the Tri-x (320/400) recommendations on the assumption that these are both "old school" type emulsions. That's the extent of my brilliant ideas though...

Thanks in advance!

p.s. I suppose this could be of some use -> http://www.digitaltruth.com/products/efke.php

 

[nworth]

For color separations, you will probably need to do some experimentation to get the exposures right on. But filter factors provide a starting point. PL- 100-M is a pretty ordinary Type B panchromatic film. For similar Kodak films, the tungsten filter factor for the No. 29 filter is 8. There is no listing for the 47B or 61 filter, but the factor for the 47 (slightly lighter than the 47B) is 10 and for the 58 (somewhat lighter than the 61) it is 8.

Kodak Pamphlet E-80 (January 1972), "Kodak Dye transfer Process". lists the following recommendations for direct separations using Kodak Super-XX film (ISO 200) with 450 foot candles of 3200K incident illumination on the subject: No. 29 - 15 seconds at f/16; No. 61 - 12 seconds at f/16; No. 47B - 20 seconds at f/16. It recommends developing direct separation negatives to a gamma of 0.90. For separations from a transparency, the same document recommends using an enlarger, setting the lens to f/4.5, and adjusting the illumination to give 3 foot candles at the exposure plane without filters. Then expose Super-XX as follows: No. 29 filter - 25 seconds at f/8; No. 61 - 15 seconds at f/8; No. 47B - 30 seconds at f/8. Develop the film for a gamma of about 0.70. A density of 3.0 in the transparency should give a density of about 0.35 to 0.40 in the negative.

I hope this helps

 

[2F/2F]

Isn't the color sensitivity of the Efke films slightly different than modern panchromatic films? I don't think they are as responsive to red as most. So I would do some tests to see what sort of exposure compensation it takes to match the density of an unfiltered shot of a gray card.

 

[holmburgers]

Thanks nworth, that seems very useful for starters. And 2F², I think that is the case for the slower 25 ISO films only.. at least that's what I read just today.