Quote Originally Posted by RalphLambrecht View Post
in general a dedicatedmacro lensshould deliver the best optical quality and the diopter lens should be the worst withe tubes somewhere in betweenbut I was positively surprised by the Carl Zeiss diopter for the Hasselblad.Those guys know what they are doing!I'm looking forward to check up on the idea of using enlarger lenses for close-up photography.You can get SKGrimes to make you an adaptor that doesn't break the bank but delivers superior quality with your enlarger lens(just a theory of mine at this point)
Ralph, back when I was a beginning photographer Modern Photography ran educational articles on roughly a two year cycle. Every other year they published a piece "Extension tubes of diopters -- which is better?" The answer never changed. Which is better depended on the lens. The only way to know which was better with the lens in hand was to try both. MP is long gone but I don't think the answer has changed.

Re enlarging lenses for closeup, the results depend on the enlarging lens and on the magnification. Until I read Schneider's documentation and did some testing I believed that a Componon-S would be better for closeup work that a plain Componon and that a plain Componon would be better than a Comparon. All mounted facing normally, all used in the range 1:1 - 1:4. Turns out that the Componon-S is indeed a bit better than a plain Componon, but at that range of magnifications a Comparon is the best of the three. This because Componons are optimized for making larger prints (= taking at lower magnifications) than the humble Comparon. Who'd have thought it?

As for dedicated macro lenses, far and away the best ~100 mm macro lens I've ever used that will cover 2x3 from 1:5 up is a 100/6.3 Neupolar. So you're right. But and however, my relatively humble 4"/5.6 Enlarging Pro Raptar is as good at the same magnifications from f/11 (set, not effective) down. So you're wrong.

The moral of all this is that generalizations based on general principles are risky.