I have a Beseler 45MX with a Zone VI cold light head. There is no filter drawer/slot above the lens, so my choices for placing the filters seem to be:

1) Lift the cold light head and put the filter under it, on top of the milky glass, or

2) put a small filter in the filter holder below the lens. Although this would be far more convenient than the first option, it seems to me that I've read that filters should be above the lens rather than below. Is this important, or should I just use the below-the-lens option?

-- Ben Crabtree (bcrabtree@mn.rr.com), April 24, 2002

Answers

When I used an old Focomat 1C I had to put the filter below the lens. I didn't find any loss in quality of the prints. I did several prints with and without the filter but coudn't see any differencies. So in my opinion if it is more convenient for you to put the filter under the lens do it. /Lars

-- Lars Kristensen (krislars@algonet.se), April 25, 2002.

Putting the filter under the lens is the second choice, but I find that it works fine.

-- Keith Nichols (knichols1@mindspring.com), April 25, 2002.

In his book, Post Exposure, Ctein determined that there was no reduction in quality in below the lens filters. Obviously, this assumes a clean filter with no scratches or blimishes that could cause a problem below the lens. I have also read the the filter should be no further than an inch or two below the lens, but I don't know if this makes a difference (does anyone know?).

One benefit of below the lens is that it is easier to change filters if you use multiple filters for a print without disturbing your print setup.

-- Jim Rock (jameswrock@aol.com), April 25, 2002.

Thanks for the info. Jim's point (changing filters) was my main concern, as I want to try split filter printing. I'm glad to know that there's no evidence suggesting that below-the-lens filters cause measurable image degradation.

-- Ben Crabtree (bcrabtree@mn.rr.com), April 25, 2002.

I also use the Beseler 45MXT and my first choice is to use the filters below the lens with the rotating filter holder supplied with the enlarger. The one comment I want to make about this method is that I sometimes experience the "Newton Rings" effect when the negative has large areas of flat gray (around zone iv or v). With most negatives I don’t experience this, but occasionally it does occur. I have determined that it is the filter which causes the rings, because upon removing the filter, the effect disappears. I then use my secondary method, which is placing the filter directly upon the negative carrier. I have never had any ring problems when placing the filter here, but if the filter is not clean, it can cause dust marks on the print. This method also makes it difficult to change filters during exposure times.

-- James Webb (jwebb66@yahoo.com), April 26, 2002.