Infinity out of focus

[AlanZ]

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I’m using an M mount Voightlander 35mm lens with a “dumb” adapter on my TL2. I shoot a lot of landscapes and usually shot at f8 and I almost always focus at infinity. My issue is when I zone focus the lens to infinity the images seem just a little out of focus. When is infinity not infinity?

[jaapv]

When you zone focus, obviously... Zone focus is accepting a certain amount of unsharpness outside the plane of focus by definition.
Quote: Günther Osterloh: "If you want the horizon sharp, you focus on the horizon".
Might I suggest replacing zone focus by focus stacking in landscape photography? It is really a massive quality jump.

[ramarren]

I think what AlanZ is noticing is that most mount adapters typically have slightly short mount registers, which throws the focusing scale slighty off its calibration. There isn't any real fix for this (aside from finding a mount adapter that is manufactured with a closer spec to the original  mount registration): you have to actually focus through the lens to achieve infinity focus correctly, rather than just setting the focus distance at the infinity mark. 

Lens mount adapters are usually made this way to ensure that all adapted lenses, despite their variances, will be able to hit the infinity mark, so it's hard to find one where the mount registration is precisely on the mark the way the original lens mount is. The Leica M Adapter L is one of the best in this regard. 

G

[jaapv]

Ah, yes, you are right, if I reread the OP I guess that he means scale focus instead of zone focus. I concur with the explanation.

[jev]

On 9/19/2020 at 9:43 AM, AlanZ said:

I’m using an M mount Voightlander 35mm lens with a “dumb” adapter on my TL2. I shoot a lot of landscapes and usually shot at f8 and I almost always focus at infinity. My issue is when I zone focus the lens to infinity the images seem just a little out of focus. When is infinity not infinity?

Shoot at f16/22 etc. and bracket or better off, get Leica adapter, then you can see a focus confirmation in viewfinder. I am not sure why you shooting landscapes at f8

Edited September 20, 2020 by jev

[ramarren]

1 hour ago, jev said:

Shoot at f16/22 etc. and bracket or better off, get Leica adapter, then you can see a focus confirmation in viewfinder. I am not sure why you shooting landscapes at f8

Depending on the focal length and desired effect, f/16 and f/22 might incur too much image degradation through diffraction. With my V 10mm, it gets noticeably softer as early as f/11. 
 

G

Edited September 20, 2020 by ramarren

[AlanZ]

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I use f8 because the 2 lens I use most are sharpest center and edge at f8. Sometimes f11.

[jaapv]

On 9/20/2020 at 9:48 PM, ramarren said:

Depending on the focal length and desired effect, f/16 and f/22 might incur too much image degradation through diffraction. With my V 10mm, it gets noticeably softer as early as f/11. 
 

G

I agree - using aperture to create deep DOF  in static photography like landscape or macro is really getting to be an obsolete technique these days, although one is stuck with it using film. It is being replaced by focus stacking, some cameras even facilitate this by offering post-focus.Not to mention that focus stacking leads to better image quality and more control.