Using VC Filters Below the Enlarging Lens : LUSENET : Large format photography : One Thread

I have a chance of getting an 8x10 enlarging head that would require me to use variable contrast filters below the lens.

Does someone have experience with this? Is this possible while still maintaining quality? VC heads are expensive. Has anyone done testing to compare using filters above the negative versus below the enlarging lens? What filters would you recommend for below the enlarging lens filtration?

-- neil poulsen (, March 20, 2001


I use VC filters below the lens on my old Omega D3 enlarger. I made a wire frame out of a coat hanger and mounted it under the lens. Some might say you loose some quality, but I enlarge to 16 x 20 and I've never been able to see any difference between prints made with a filter and those without a filter. Try it yourself...just hold a filter under your lens and make an exposure and see if you can see a difference.

-- Don Sparks (, March 21, 2001.

I think these gelatin filters come in two grades, or at least they used to.
The CP (colour printing) grade is meant to be used in a filter drawer, while the CC (colour correction) grade is for below lens use.

-- Pete Andrews (, March 21, 2001.

Ctein in "Post Exposure" has this to say: "According to my tests, this makes no difference. I set up a high resolution test target with my 55mm Computar lens at optimum aperture and examined the projected aeriel image with no filter under the lens, with modern thin filters under the lens and older cast-plastic filters under the lens. In all cases, I could see a clean 320 lp/mm in the center of the field and more than 280 lp/mm at the corners. I could not convince myself that I saw any degradation in image quality with the filters in place, no matter how hard I looked. As long as your VC filters are not scratched enough to create serious flare, I can see no reason for avoiding below-the-lens filters. That surprises even me, but its true." Cheers, DJ.

-- N Dhananjay (, March 21, 2001.

FWIW, I've been using vc filters under the lens for several years now while enlarging 35mm (enlarger predates vc paper, hence no filter drawer), and haven't noticed any bad side effects. So long as the filters are kept free of dust and scratches, I can get prints made through the filters that are sharp as all heck. If a 35mm negative can withstand being enlarged through a filter, I imagine an 8x10 negative would be absolutely fine.

-- David Munson (, March 21, 2001.

Neil: Even if your arrangement has no filter drawer above the lens, you can get the Ilford filters as sheets and stick them over the negative under the light source. They come up to 12X12", then you wouldn't have to worry about it. Like the others, I have tried side by side tests with the plastic Ilford filters and I can see no loss of sharpness. It surprised me, but I couldn't tell the difference.

-- Kevin Crisp (, March 21, 2001.

It makes no difference. Anyway, all I can say is that I printed on a condenser head, which many seem to think is second rated to a diffusion head, and with the filters below the lens. The prints used with the above method have won competitions and awards. Its your talent, not above or below filters that counts. What ever paper you're using, Ilford has their filters, Kodak their's. Any other brand of paper, contact the company and ask which of the two brands of filters work better with their paper. Good luck.

-- Ravin (, March 21, 2001.

P.S. I know above is supposed to be better then below but I often wondered, when focusing, you can move the filter out of the way to get just white light when its below the lens, but with a filter drawer what do you do when focusing? And, when opening the filter drawer, doesn't that give dust an opportunity to fall in on the negative? Don't get me wrong, my dream machine is a VCCE enlarger. No Callier effect, just dial in the filters, and it compensates for more exposer time when going to a #4 or more filter. AHHH, someday.

-- Ravin (, March 21, 2001.

Assuming you'll be using a glass carrier for your 8x10 negs, using filters above the neg would mean two more surfaces to keep dust-free. Also, filters in that size are really expensive. Use the filters below the lens, but keep the distance between lens and filter within one quarter inch.

-- Steve Wiley (, March 22, 2001.

So Ctein has a plate with 1.5 micron bars and spaces on it has he? The man's full of surprises. Or full of something.

-- Pete Andrews (, March 22, 2001.

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