Focusing question.

[Robinyuill]

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Hi there. I've seen posts about focus shifting etc and had posted in customer fotum about calibration of lenses and cameras. I have Monochrom and just sent it and 50, 75 Summiluxs and 135 Apo off for checking at Leica. I'm a bit confused when it comes to this focus shift subject. I have Tri Elmar 28/35/50 and 35 Summicron (IV) as well. Is it the nature of the Leica system to have a change of focus plane when you change f stop after focusing on a subject? I saved hard and was lucky to get the Summilux lenses and it seems a shame that I can't use them at 1.4 if I can't get a focused image. Is there a simple explanation? Regards Robin.

[Rus]

Focus shift should not be confused with misalignments between the RF mechanisms of the lens and the camera.

Focus shift is inherent to the optical design of certain lenses (e.g. Zeiss M Sonnar 50 1.5, Summilux 35 1.4 ASPH v.1). There are many other lenses that do not display focus shift across different aperture settings. Many of those lenses that display focus shift due to their designs can also be adjusted to focus correctly at wide open or your aperture value of choice (often close to wide open, since at smaller apertures the greater DOF quite often masks the focus shifting issue).

 

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[michaelwj]

As Rus said, focus shift is inherent in some optical designs. It not only has nothing to do with RF calibration, but is not only an issue on RF. many SLR lenses also display focus shift which can be just as problematic as you focus an DLR wide open and then it is stopped down to take the image.

Do you have your lenses back yet?

[Robinyuill]

No, haven't got the camera or lenses back. The focus shift issue is being explained and I hope that when the equipment comes back it will have been adjusted if it was needed. The next option would be saving for M10 with the live view and better viewfinder! ( or get better spectacles )

Thanks.