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need to calibrate the focus when using ltm mount lens on M8/M9?(like canon ltm 50mm )


pfha1679

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need to calibrate the focus when using ltm mount lens on M8/M9?(like canon ltm 50mm )

I think there is no reason screw-mount lenses have more need of calibration than bayonet-mount lenses. But I like to have all lenses calibrated if only for peace of mind.

 

It is also important to get a high-quality screw-to-bayonet adapter, Leica or Voigtlander for instance, because in using an adapter you're adding two more surfaces for manufacturing tolerances to be off a bit.

 

Doug

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Two variables that often mean you need to calibrate a screw-mount lens for a Digital Leica: 1) Different Manufacturers make assumptions of how film sat in their cameras, 2) Manufacturers optimize their lenses for best performance at a specific aperture setting.

 

I've found that Nikon lenses were optimized for best results at full-aperture, Canon optimized their lenses ~1Stop down. Same with the Leica Summarit, 5 that I've used were best at F2.8 at close-focus. With film cameras, this often went unnoticed. With pixel-peeping, "what a difference an inch makes". My Canon 50/1.5 is now optimized for wide-open use, required changing the shim.

 

If the lens is back-focusing at all apertures, it needs to be adjusted. If it slightly front-focuses when used wide-open, most likely it's optimized for 1~2 stops down. This can usually be changed by adjusting the shim. Some lenses are easier than others.

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