In order to choose between these focal lengths, I want to determine what the difference will be in reproduction ratio/print size for a given lens-to-paper distance. On an enlarger that I just bought, the maximum column height, taking into account the height of my ceiling and the maximum drop of the baseboard (it's a floor standing enlarger that allows adjustment of the baseboard height), will be about 7 feet. Of course, the height of the enlarger head, etc. will reduce this. Can someone tell me what the formula is for determining print size for a given lens-to-paper distance?
Are there other considerations in choosing between 135mm and 150mm and, if so, what are they?
Finally, recognising that this has been discussed before, and rather inconclusively, I would appreciate any comments about choosing between an Apo and non-Apo lens, especially in relation to black and white printing.
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