The rear element of any SLR lens that\'s compatible with the 5D mirror will be far enough from the sensor plane that offset microlenses or their lack will not make a significant difference on IQ. It\'s only an a non-SLR camera like the M8 where rear elements can get within a few mm of the sensor plane where this becomes an issue.
A lack of telecentricity may remain an issue with IQ on SLR lenses, but will be primarily a vignetting source rather than a source of softness since most retrofocus designs are relatively telecentric by design.
Then why does the DMR also have offset microlenses? Also, why are these problematic lenses on the 5D fine on the DMR, (though a 1.3 crop) or slide film?
Robert
IIRC the DMR uses microlenses, but they are not offset. This is supported by all the information I\'ve been able to find on it. The M8 introduced offset microlenses to compensate for the problems inherent in using non-retrofocus 35mm format wide-angles with sensors larger than DX crop. Anyways the DMR is not anything close to FF so the issue weekh describes would not necessarily be visible on it.
As to slide, well frankly that comes down to 2 things. First off, film is slightly less sensitive to plane of focus placement (Since it has an appreciable thickness and an R series body will not hold the film truly flat anyways as that requires a vacuum back). Secondly, are you sure the results are that good? You\'d need a high-res scan and some 100% inspection to really compare results from film to digital and that rarely happens in a truly comparable fashion (Witness Michael Reichmann\'s hilariously poor film vs digital comparisons over at L-L).
If what you suggest was truly the case the Leica R 19mm would have worse issues than the 21-35 on a 5D, and the 21 Distagon would have similar problems. The fact that these supposed disconnects in performance are limited to a single lens design indicates an issue with the lens design, not the camera.
Mar 01, 2009 at 02:51 PM
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