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p.2 #6 · p.2 #6 · Is there something wrong with this Lux 50 ASPH? | |
I don't have any experience with Leica M lenses--I'm an R guy--but the NEX-7 theoretically resolves 125 lp/mm. The MTF charts go to 40 lp/mm. Seeing as how the resolution drops more than double from 20 lp/mm to 40 lp/mm at 10-12mm from center, compared to peak resolution, I'd expect to see even more significant drops as the lp/mm count approaches 125.
Sure, the left side seems less sharp than the right, but even shimming with the thinnest foil commonly available is going to be 15 micrometers or so thick, probably too rough of a gauge to make it perfect. That kind of precision is why good adapters cost so much--and even they aren't perfect, just better.
Bottom line, for me: it looks like it is in focus, just not resolving as well as you'd like. There's a reason that Leica is making the 50 APO and Zeiss the Otus, and that's because current sensors can make even superb lenses like your 50 Lux look "bad." Add that the filter pack on the NEX-7 is in no way friendly to M lenses, and you see what you see. Personally, I despise my Metabones adapters as things in their own right, but they let me get the kind of drawing I want on a digital sensor that doesn't cost what an M 240 costs so I'm glad to be able to use them. Your lens seems to draw very nicely. Your kit probably can produce prints that rival medium format film, though with a much smaller size and far less hassle. Small compliment for a pixel peeper, perhaps, but I shoot Leica lenses for how they balance optical attributes to generate quality total images, not for MTF curves alone.
That all said, take a few similar pictures with either the top or bottom edge in focus. That should show the increasing resolution, as your corners are at 14.4mm from center. Note the difference in sagittal versus tangential resolution, and at different apertures. If all that lines up with the Leica tech doc, your lens is probably fine.
Hope this helps. Well wishes for good photography--
Jon
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