I'd appreciate some suggestions on how to solve a problem. I have the big Besel er column enlarger with the Beseler/Aristo 8X10 head on it. I have a Nikkor 210 mm lens which is very large in diameter. The variable contrast filters come in little plastic frames (too small for this 210 mm lens) or 5X5 sheets (maybe 6X6 , I forget). If I want to enlarge a 5X7 negative (placed in 8X10 negative carri er with masking) how to I use the filters? The sheets are big enough to put abo ve the negative, there is no intermediate filter drawer which could hold the fil ter before the image gets to the lens, and short of designing and machining some gizmo to hold a big square sheet below the lens, I don't know what to do. Mayb e rigging up something to hold the little mounted filters against the back side of the enlarging lens? I tried that but they usually get knocked out of place w hen I try to put the lens board back in. If somebody made 7X7 filters that woul d do it, I could put them under the light source. Maybe two of the small sheets butted up against each other? I'd appreciate any thoughts you have. Thanks in advance.