100mm enlarging lens

[doc]

can anyone tell me under what circumstances one would use a 100mm enlarging lens ? what size negative? what size enlargement? thank you.

[Sean Billy Bob Boy yates]

100mm would be for medium format negs, 6 X 9, to 6 X 4.5 and the size of the print would be limited by the maximum distance between the enlarger head and the easel.

[Franco Rallo]

Hi David - Lenses of focal lenght from 100 to 110 mm are normally used on 6x9 cm format cameras; a good rule for enlarging is to mount on the enlarger the same focal lens of the camera used for that particolar negative, so it will cover well the whole negative size. Of course it is possible to use other f.l., but with a shorter f.l. the results are good only for the central part of the negative, and with a longer f.l. you will get a smaller enlargement unless you move the enlarger head far away from the paper. Generally, a medium-good 100 mm enlarger lens will cover a square of 9x9 cm negative without aberrations and good resolution; it is advisable to stop the lens at f/8 or f/11 to get the best results. It is also possible to use the same lens (100 mm) to enlarge a part of a bigger size negative (9x12, 13x18 or 18x24 cm) provided that in your enlarger could be possible to move the negative and placing the interesting part in line with the lens axis. Remember also that, if your enlarger works with condensed light (not diffused), each lens should be coupled with a specific condenser to assure the best uniformity of light distribution on the negative and on the final print.In effect this is not very important, and I use the same condenser with 110 mm f.l. (printing 6x9 negative) and 150 mm f.l.(printing 9x12 negative). Bye, Franco

[Darron Spohn]

One of my friends recently borrowed my darkroom to print a 4x5 negative. Sufferi ng a bout of temporary dyslexia he mounted the Nikkor 105/5.6 lens instead of the 150/5.6 on my enlarger. I've n ever seen so much burning in the corners required. I thought his old taking lens was the culprit until we wer e cleaning up and I was putting the lens away. We had a good laugh about it, and I can still make his face turn red just by asking him what size lens he needs for a 4x5 negative.

Stick with 6x7 to 6x9 negatives in this focal length. The enlargement size depe nds upon how high your enlarger goes. I can make 16x20s using my 105 lens on a 6x9 negative. I use the 80 mm len s for 6x6 and 6x7.

[Brian Ellis]

I use a 100 mm lens for 6x7 negatives to make sure of even coverage throughout the print. I could get by with a slightly shorter lens for 6x7 but the only "penalty" for using the longer lens is that the size of prints that I can make is slightly smaller than with a shorter lens. However, for me it was worth paying that minimal penalty in order to be certain that the light coverage would be even.