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View Full Version : Voightlander Apo-Lanthar 150/4.5 lens: optimum aperture?



Ian Binnie
17-Apr-2000, 19:28
Does anyone know what the optimum aperture is for this lens? A old product broc hure suggests that it is close to the maximum 4.5 aperture. This is contrary to the usual "two stops down" rule. I don't really have the facilities or the tim e right now to do any valid testing, so I'm hoping that someone has already foun d the answer. Thanks in advance.

Richard Rankin
17-Apr-2000, 20:55
The latest Photo Techniques (May/Jun 2000, Vol 21 No 3) takes an interesting look at the 'two stops down' myth. Howard Bond has a very enlightening (and somewhat depressing) article called 'Resolution Loss to Diffraction'. A lens with a larger maximum aperture may need 5 stops down and one with a larger max aperture (say f9) may only need 0 or 1. The article is worth a read.

Richard Rankin
17-Apr-2000, 21:22
Sorry about that:

A lens with a larger maximum aperture may need 5 stops down and one with a **smaller** max aperture (say f9) may only need 0 or 1.