Yellow filter for cold light question

[Ben Calwell]

I haven’t tried this yet, but would a No. 8 yellow camera lens filter work as a close substitute for a 40 cc yellow filter for use with a cold light head and VC paper? Or perhaps a No. 0 or No. 1 Kodak Polycontrast filter?
B&H lists 40cc yellow gels, but they’re pretty expensive.

[C. D. Keth]

A #8 is significantly more dense than a CC40Y. I’m having trouble finding reliable spectral pass curves for both filters but I can find that the recommended lens correction for the #8 is a stop and only 1/3 stop for the CC40Y.

Edit: See new post just below for more spectral absorption information.


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[C. D. Keth]

Took a bit but I found reliable, like-formatted absorption curves for both filters from Kodak. Notice how each graduation of CC00Y filters let’s in some, but progressively less blue. They are produced with much finer control. The #8 yellow is a less “defined” filter and won’t replace the CC40Y adequately. It would make the same general effect on VC paper but that effect won’t be precise enough to be useful.




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[Ulophot]

I would look on the auction sites for something like this:

https://www.ebay.ca/itm/Ilford-Cibac...MAAOSwFmtdbtgJ

This one is a 30, which is close; you may find a set or a 40 single.

[Kevin Crisp]

Not wanting to retube both my enlargers, I really gave it the college try with filtration to make the traditional color tube work with modern VC materials. I never got anywhere near even contrast steps and "numbers" that were remotely what a #2 or #3 etc. should look like. I'm not saying it can't be done, but I sure couldn't get it to work. Eventually I got the aqua tubes from Aristo and things worked after that.

[Ben Calwell]

Thanks everyone, and Chris thanks for the detailed graphs and info. I called the Light Sources company (light-sources.com), and they have some V54 tubes (the ones that work with contrast filters) for sale for $175 that would replace the tube in my older Aristo cold light head. Don't want to spend that much, but maybe I should given the headaches of using yellow filters with my current head. And graded papers are apparently a thing of the past.

[Kevin Crisp]

Be extremely careful in removing the old tube and installing the new one, particularly where the old tube is glued in at the ends with what looks like clear silicone sealant. Really easy to break these and it puts mercury all over the place when you do.

[Merg Ross]

This is a familiar problem. Maybe try Rosco gels.

[C. D. Keth]

This is a familiar problem. Maybe try Rosco gels.

Rosco makes similar CC lighting gels in courser steps. R4515 is what they call the 15Y strength. They also do 30, 60, and 90. Just change the last two digits of that code. A Y45 strength (a Y15+Y30) might be close enough.

I don’t know if lee uses the same gradations or if you could build a 40Y from their numbers.


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[Drew Wiley]

V54 tubes respond best to green versus blue filtration. If you are comfortable with split printing, all you need is one deep blue and one deep green filter. Most often I just use the light unmodified, and then if necessary, tweak a little more or less contrast after the primary exposure. I think the whole obsession with trying to peg specific hypothetical contrast grades is pointless, making a simple problem unnecessarily complicated. But if you do need to achieve maximum contrast with VC paper, a 47B blue is going to do it much better than magenta; likewise, at the low contrast end, a 58 green is going to be more effective than anything yellow. I use glass filters over the lens.