Re: A thinner sensor stack may be possible after all!
I once owned a Heliar 15/4.5 first version. I used it on a NEX camera (can\'t recall which model) and a Ricoch GXR-M. Therefore, my experience is limited to APS-C sensors. I expect that a full frame camera will show even more differences between center and corners..
My five cents :
1- Excellent relationship between size/price/optical performances but not a match for far more expensive glass .like a ZM 15 or a Leica WATE -The Heliar 15/4,5 isn\'t a sharpness champion at any f/stop. ( best aperture seems to be between f/5.6 and f/8. F/11 isn\'t the best choice for assessing sharpness).
2-The lens has a noticeable field curvature -even on film cameras. If you focus for better sharpness at the centre, corners/edges won\'t be pin sharp. Likewise, focusing at the corners degrades somehow performances at the centre. You may choose to focus in-between or stop down to f/11-f/16, where the effect almost disappears due to depth of field, but the general performance past f/8 worsens, as stated above.
3-Field curvature with the Ricoh GXR-M was visibly lower than with the NEX and it was easier to get a fair balance between centre and corners This was surely because of the thinner filter stack of the Ricoh
4-Copy variance might play a significant role as well. Cosina\'s QC seem\'s to be less strict with the Voigtlander line than with the lenses they make for Zeiss. (ZM, ZF, etc..) This is logical, considering the price difference.
Jul 25, 2015 at 04:35 AM
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