Enlarging Lenes Question. Which one? And why?

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Hi,

I have just upgraded to Medium Format Photography. I now work with 6x4.5 format and 35mm. My question is simple. For my enlarger I have two lenses a 50mm for 35mm and a 105mm for 6x7. I will need a 75mm for 6x4.5 but why the different lenses for the different formats? Like what would happen if I used the 35mm and/or the 105mm on 6x4.5 negitives? What would the result be?

Thanks, Sean Micha Siegel

-- Sean Micha Siegel (MicaSoHo@aol.com), January 01, 2000

Answers

Couple issues here. First, the lens has to cover the format you want to use. There are some wide angle designs that allow a shorter lens to be used, but your 50mm probably won't cover 6x4.5 negs. The 105mm will cover them, but you'll have to raise the enlarger higher for a given size print. That may be acceptable if you aren't making large prints. Whatever focal length you use, the condenser system (if you're using one) should be designed for, or adjusted for, that focal length. It should be directing most of the light through the lens, not wasting it by illuminating the lens board. Finally, there is a quality issue. Lenses are designed for best performance within a range of magnifications and for a specific format. You have quite a bit of leeway here, but for best results you should operate the lense within the conditions it was designed for. I'd try the 105mm and see how the prints look. If you're happy with it, save your money. If not, buy a nice EL-Nikkor, Rodenstock, or Schneider!

-- Conrad Hoffman (choffman@rpa.net), January 02, 2000.

Sean, I would tend to agree with Conrad. As a rule of thumb, you can use a longer lens for a smaller than maximum negative size, but not vice-versa, this will result in insufficient coverage, i.e. not all of the neg will be projected onto the easel. Some even recommend using a slightly longer lens than standard, they believe using only the center of the field of coverage is sharper. I would recommend buying first the longest lens you will need for the formats you are enlarging and use it for the smaller ones as well (100mm for 6x9, 6x7 and 6x4.5 and even 35mm if you don't enlarge too much) and acquiring a shorter lens only if you really find you need it for the larger prints from the smaller negatives. If you use condensers (which I don't) then make sure you have them set for the lens you are using and not for the negative size. Some enlargers have "settings" for the condensers marked in film format sizes. This is misleading. They simply assume you are using standard length lenses for whichever film format you are enlarging (50mm for 35mm film, 150mm for 4x5, etc.). Cold light heads do not need to be adjusted for different focal length lenses. Regards, ;^D)

-- Doremus Scudder (ScudderLandreth@compuserve.com), January 03, 2000.

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