I have a nice set of large Kodak gels of an indeterminate age. I have cut them down to use in my 4 x 5 enlarger and covering the bulb I use for contract printing 20x24. But they only go up to #4.
I wanted to add #5 but could not find anything by Kodak used on line that was big enough.
I did find a big new sheet of #5 Ilford and ordered it. It is rather pink compared to the dark amber #4 Kodak.
Do Kodak and Ilford use the same grading systems for filters?
No.Originally Posted by FrancisF
...that said, you can certainly use an Ilford #5 filter to get more contrast than you're getting from the Kodak #4 filter.
If you want to check if you're getting maximum contrast from your set of filters, make a print using your highest contrast filter and then on using a Wratten #47 blue filter. (You can do this using a step wedge to get quantifiable results - just count stripes - fewer = more contrast).
I find that the #47 filter gets me significantly more contrast than the 170M setting on my Chromega heads.
Best,
Doremus
I tried to mix and match Kodak and Ilford, and quickly realized I was wasting materials and time. They have different effects on exposure time which are not easily translated back and forth. I ended up buying a full new Ilford set.
Thanks for that info. I'll have to give it a try -- not that I have a #47, but it makes me wonder if I can increase contrast by having magenta in the enlarger head -- dichromatic 170M -- and a #5 under the lens.
Should I try it? Probably a waste of time, right?
No magenta filter is going to be stronger than an actual 47 blue if it's not faded. Only 47B is stronger than that. But it's far more practical to use a real glass 47 filter below the lens.
No. The contrast range is determined by the spectral sensitivity of a paper and the spectral content of the exposing light - which depends on the light source and filtration. It doesn’t make sense to ignore everything but the filter and/or assume a 47/47B will produce higher contrast than a magenta Ilford #5 filter. Look at an additive colour wheel. You ought to know this stuff with all your colour experience!
Kodak changed its "Polycontrast" filters in about 1989. The older set came in a bright yellow plastic box and went from grade 1 through 4. They are not very useful with modern variable-contrast papers. The newer version of the kit has filters from "-1" to "5+" and does work well with today's papers. The blue filter will give you the most contrast, but beware of focus shift.
Focus shift is really only an issue with an enlarging lens that isn't well color-corrected. Most newer (relatively speaking) enlarger lenses won't have an issue. The problem arises when we focus using "white" light, which has a strong red component, and determine the focus with all that red in the mix. Then, if we expose with a high contrast filter, using mostly blue light, and the lens focuses blue in a significantly different plane than the red, sharpness can be affected.
Still, this is a non-issue with a quality enlarging lens.
Doremus
If you have a step wedge, it's a pretty quick test. Just expose the wedge under both filtrations and count stripes. The exposure only has to be close enough to get the entire range of stripes from Dmin to Dmax.
Doremus
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