I would like to be able to print up to a 16X20 image size from a 4X5 negative, but suffer with a low ceiling. I understand the possibilities of projecting horizontally, lowering my easel or cutting a hole in the ceiling, but for reasons of comfort and time, neither are attractive alternatives.

At present, I am using a 150mm enlarging lens, and would like to know what a change to 135mm or 120mm wide angle would offer. I have not found data on the projection angle of enlarging lenses. Can anyone offer either experiential information or a method for calculating image size, based on the distance from lens to easel?

Thanks so much.

-- Henry Friedman (friedlew@worldnet.att.net), September 16, 2001

Answers

You should probably set your enlarger on a lower table, if your problem is the enlarger head bumping the ceiling. A shorter lens, say 120mm or even shorter, would solve your problem, too. And that lens will be valuable should you want to print from smaller negatives. Tilting the enlarger head 90 degrees presents the problem of how to put the paper in the just the right place and exactly parallel to the negative. Knocking holes in the ceiling sounds like the least advisable way to go.

-- Keith Nichols (knichols1@mindspring.com), September 16, 2001.

Define L to be the maximum possible distance from the negative to the photo paper and f to be the focal length of the enlarging lens. Be sure to measure both in the same units, e.g., mm. Then define r = L / f. The maximum magnification is then m = r/2 - 1 + sqrt (r*r/4 - r). In words: m = (r divided by 2) minus 1 plus the square root of the quantity (r squared divided by 4 minus r). If m is >= 4 then you will be able to make 16x20 prints.

Most 135 mm enlarging lenses will cover 4x5. Enlarging lenses of 120 mm focal length that will cover 4x5 are special wide-angle products that will be on the expensive side.

-- Michael Briggs (MichaelBriggs@EarthLink.net), September 17, 2001.

You must have a very low ceiling or a tall lamphouse on your enlarger. A 20x16 from 5x4 is only just over a 4 times enlargement, and needs just under a metre from negative to baseboard with a 150mm lens. A 135mm lens is about as short as you can use, and would reduce this distance by only about 160mm.
I'd go with the suggestion to make a lowered platform for the enlarger. Horizontal projection presents problems with a lot of LF enlargers, such as the neg carrier falling out, for one. An easier formula to find the negative to baseboard distance is (f+f/m)x(m+1); where f is the lens focal length, and m is the magnification.

-- Pete Andrews (p.l.andrews@bham.ac.uk), September 17, 2001.

On many enlargers, you can clamp the baseboard to your table and rotate the column and head over the floor so you project the image onto a lower platform, or even onto the floor. You might need a simple alignment system to assure the enlarger negative and lens stages are still parallel to the easel, but it does save the fuss of moving your enlarger to another table height or raising the ceiling.

-- Tim Nelson (timothy.nelson@yale.edu), September 17, 2001.