Amazing...in very carefully examining center and edge detail in a 20x30 print made with a 180mm Companon-S, and the same print as a 30x40 made with a 150mm G-Claron...the Claron wins! How is this possible? And the Claron, to boot, has an amount of dust in between elements which might be cause for some concern. Companon-S Stopped to f/16, Claron to f/22. Heiland LED VC light source. Go figure!
Unless you are testing multiple copies of each lens sample variance will come into play. You may have a better than average G-Claron or a worse than average Companon-S or both. There is no guarantee that repeating that test with two other copies of those lenses would have the same result at all.
Gosh, Pere, you really think Schneider was that sloppy with quality control! The difference he is seeing is inherent. G-Clarons were designed for close-up flat work, though they also excel for general photographictaking. I'm referring to the plasmat versions in shutter. But G Claron we're also marketed in barrel, and differ from enlarging lenses only with respect to a smaller maximum aperture.
Both lenses used to enlarge from 5x7 negative...Companon-S to 20x30, G-Claron to 30x40. Companon-S is perfectly fine...but G-Claron excels despite greater magnification. No big deal...just a bit surprised.
1) Dust in the lens elements should not be an issue.
2) The typo in the OP confuses me. CompOnon? CompAron? Componar? All were Schneider enlarging lenses, all different.
In any case, now you know which lens to use. Try the test again in six months.
Not surprised. Been using APO "process" camera lenses in a Durst 138 to enlarge 5x7 negatives for decades. Same test was done decades ago, APO Nikkor, APO Artar, APO Ronar and etc had better performance than Componon, Componon S, Rodagon and etc.. The APO process lenses remained, "Enlarger" lenses found new homes.
Worth noting lenses like APO process lenses, G-Claron and similar also make very good taking lenses too.
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