Auteur: Dan Fromm
Date: 30-01-2006 17:00
Herve, in my tests of macro lenses, I found that from 5:1 up the best aperture was usually wide open. Exceptions, reversed 55/2.8 MicroNikkor AIS and reversed 25/1.9 Cine Ektar II, both are better at, respectively f/4 and f/2.8, than wide open or 2 stops down. Above 5:1, diffraction is your enemy.
Please tell us more about how you are lighting your subject.
I have great difficulty ensuring good focus with the modified Durst M606 I usually use as a copy stand. It's column is a little flexible, the brackets I use to attach the camera plus bellows etc. are a little flexible, so I have to be very careful to make sure that the apparatus is in good focus when I'm not touching it. Putting my eye to the eyepiece magnifier -- do you use one? -- can sometimes shift focus noticeably, especially at 10:1 or more.
I should use my MP-4 stand more, I think it is more rigid. But it doesn't fit anywhere.
I have three Luminars, 25, 40, 63, all in good order. I've compared mine with Charlie Barringers', his and mine are equally good. But I have the impression that Macro Nikkors are better still, and at 5:1 my 55/2.8 MicroNikkor, reversed, is better at f/4 than my 63 Luminar is at f/4.5.
Your 20/2 Olympus should be better still because, as Emmanuel pointed out, it has a larger numerical aperture.
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