Focus shift on the Summicron-M 35mm ASPH. V2 (Current version)

[jip]

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Hey there, today I noticed the following:

M10 with Summicron-M 35mm ASPH. Current version:

I focused at infinity, I shot from a hill at a skyline more than 1km away, I had something on the foreground so I used f/8 I used live view to compose, and noticed… that actually the skyline looked blurry. I then tried to focus via live view and focus looked a lot sharper for the far away skyline when focused around the 10m mark on the lens at f/8. Than when set to infinity.

When shooting wide open at f/2 the lens actually does focus properly at infinity. 

Is this a known “issue” with this lens? It is kind of annoying that when I’m doing landscapes I can’t just set focus to infinity and f/5,6 or f/8 and get sharp results. 

[adan]

I've never heard of focus shift being an issue with the 35 Summicron-ASPH - but it could be.

I'd love to see some samples (cropped enough to show what you're seeing).

Could just be the Peter Karbe effect ("You don't need to stop down modern Leica lenses!").

More seriously, is it possible that stopping down to f/8 resulted in: longer shutter speeds (more camera shake), higher auto-ISO (more noise), or diffraction blur setting in?

What was the weather? Hot rising air can produce "heat waves" that blur fine details across long distances - and can vary from moment to moment.

I caught this atmospheric-refraction blurriness in this "infinity" shot (admittedly with the APO 135) earlier this summer. A 33°C day. Post #1176

 

Edited September 20, 2022 by adan

[hmzimelka]

6 hours ago, jip said:

Hey there, today I noticed the following:

M10 with Summicron-M 35mm ASPH. Current version:

I focused at infinity, I shot from a hill at a skyline more than 1km away, I had something on the foreground so I used f/8 I used live view to compose, and noticed… that actually the skyline looked blurry. I then tried to focus via live view and focus looked a lot sharper for the far away skyline when focused around the 10m mark on the lens at f/8. Than when set to infinity.

When shooting wide open at f/2 the lens actually does focus properly at infinity. 

Is this a known “issue” with this lens? It is kind of annoying that when I’m doing landscapes I can’t just set focus to infinity and f/5,6 or f/8 and get sharp results. 

The Summicron-M 35 ASPH II I purchased last year I returned for having A LOT of focus shift. 

On top of this it had a slight back focus issue out the gate, but produced barely acceptable in focus subjects at f/2... but then the subject would only ever become acceptably (barely) in focus again at f/8. All apertures between f/2 and f/8 had the focus point way behind the subject. Especially at f/4 and f/5.6. 

The mere suggestion that this lens had focus shift was met with a lot of resistance. I understand that this lens is supposed to have little to no focus shift, at least an improvement over its predecessor. My experience over the last year of having tried several different new Leica M lenses is that copy variation is definitely present with Leica. Especially across the Summilux 50mm ASPH. I've had to date one slightly duff lens from Voigtlander out of 7 lenses, but of the 7 new and two used Leica M lens I have ordered/purchased so far I kept only one, the Summicron-M 50mm. The Summicron came new out the box with missing paint, and at f/2 doesn't quite focus reach infinity at the focus hard stop. Not a huge issue since it has focus shift and becomes a non issue at f/4. Disappointing no less.

The Voigtlander Ultron 35mm ASPH II I ordered after this easily outperformed the Summicron 35mm ASPH II copy I had. Its sad, as I really liked the design of the Summicron, and I really do prefer pairing up my camera with Leica lenses with their congruent industrial design, compared to Voigtlander.

 

Edited September 20, 2022 by hmzimelka

[lct]

Never seen focus shift at f/8 when focusing at infinity so far. DoF is so wide that everything is (acceptably) sharp from 5m to infinity more or less. Another case of misfocus for whatever reason would have my preference but i'm no techie. I would ask Leica anyway.

Edited September 20, 2022 by lct

[Jeff S]

9 hours ago, adan said:

I've never heard of focus shift being an issue with the 35 Summicron-ASPH - but it could be.

 

I no longer subscribe to Sean Reid, but he long ago reported mild focus shift at f/2.8 - f/4 with his 35 Summicron ASPH v.1.  My copy exhibited the same behavior. There have been discussions about it here over the years, including between me and @lct.

Jeff

[jakontil]

17 hours ago, Jeff S said:

I no longer subscribe to Sean Reid, but he long ago reported mild focus shift at f/2.8 - f/4 with his 35 Summicron ASPH v.1.  My copy exhibited the same behavior. There have been discussions about it here over the years, including between me and @lct.

Jeff

Quite interesting, i never realized it suffers from focus shifts, or may be because i dont stop down often enough

thanks will take this into account when using it

[Jeff S]

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6 hours ago, jakontil said:

Quite interesting, i never realized it suffers from focus shifts, or may be because i dont stop down often enough

thanks will take this into account when using it

Could well be sample variation.  Lct reported no issues with his. Only way to know is to conduct your own tests.

Jeff

[jakontil]

17 minutes ago, Jeff S said:

Could well be sample variation.  Lct reported no issues with his. Only way to know is to conduct your own tests.

Jeff

One thing i notice, when i try to focus at infinity, the focusing patch dont match, that’s all

[Jeff S]

4 minutes ago, jakontil said:

One thing i notice, when i try to focus at infinity, the focusing patch dont match, that’s all

An issue discussed in numerous threads over the years. I would have system calibrated.

Jeff

[lct]

19 minutes ago, Jeff S said:

Could well be sample variation.  Lct reported no issues with his. Only way to know is to conduct your own tests.

I have posted my tests a couple years ago but i can't seem to retrieve the links. In a nutshell i got zero focus shift issues on targets at about 1m and 10m subject distance. I mean on a Summicron 35/2 asph v1 calibrated for digital. I can post them again for those interested but they are boring to say the least.

[jakontil]

46 minutes ago, Jeff S said:

An issue discussed in numerous threads over the years. I would have system calibrated.

Jeff

You mean i have to calibrate the camera with the particular lens?

 

35 minutes ago, lct said:

I have posted my tests a couple years ago but i can't seem to retrieve the links. In a nutshell i got zero focus shift issues on targets at about 1m and 10m subject distance. I mean on a Summicron 35/2 asph v1 calibrated for digital. I can post them again for those interested but they are boring to say the least.

seems like the one i have, because from MFD definitely i have no issue, i seldom shoot landscape with this however, i notice when focus at infinity, the patch focus isnt aligned 

[Jeff S]

5 minutes ago, jakontil said:

You mean i have to calibrate the camera with the particular lens?

 

 

No, each are calibrated to an independent standard. Both should be within acceptable tolerance. Leica Service often asks for camera and lens(es) to avoid customer guesswork and back and forth shipping. 
 

Jeff

[jakontil]

6 minutes ago, Jeff S said:

No, each are calibrated to an independent standard. Both should be within acceptable tolerance. Leica Service often asks for camera and lens(es) to avoid customer guesswork and back and forth shipping. 
 

Jeff

Ah okey, thanks for explaining, i will consult with the local repair, my M10-R should be fine since i used other 50’s and 28 summaron from MFD to infinity without problem, but let’s see

[jip]

My focus is spot on with other M lenses, I might be able to send example photos once I’m back home from my current trip.

I had the Summicron-M 35mm ASPH. V1 but I cannot remember having similar issues on the M9p back then, of course I could not fact check it with live view back then.

It seems the focus moves further away as you stop down. Hence the lens focussing fine at f/2 but the focus moves further away as you stop down, and the increase in depth of field does not fully compensate for this shift.

I tried on the same location also my APO-Summicron-M 90mm ASPH. And Summicron-M 50mm and neither of those had the issue. Only the new Summicron-M 35mm ASPH. V2. 

[jip]

I actually realised the infinity focus stop just focuses past infinity even wide open. The lens is just calibrated wrong. But it does get worse when stopping down, which means there is some focus shift as well.