M10 and 50mm APO: Is back focus possible?

[BjarniM]

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I find it a bit difficult to nail the focus when using the APO 50mm on my M10.

 

Even on a tripod with the shutter speed on 1/125, the f-stop at 5.6 and the portrayed person 3-4 meters from the camera it seems hard to nail the focus, even though i'm 100% the object is dead on focus in my viewfinder.

 

The problem occours both with the built in optical viewfinder and also with the electronical Visoflex viewfinder.

 

I thought the days with back focusing problems were gone, but can it be the combination is "suffering" from back focus? Could it be some other misalignment? Or could the combination just be badly calibrated?

Edited June 24, 2018 by BjarniM

[Exodies]

If it doesn’t focus with the electronic viewfinder then it’s not a miscalibration of the rangefinder components. If the camera is ok with other lenses then send the lens to be repaired.

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[Rob L]

Or your monitor?

[pico]

If it doesn’t focus with the electronic viewfinder then it’s not a miscalibration of the rangefinder components.

 

If a lens cannot be focused by the electronic viewfinder, then it's gotta be whacked out beyond belief or human error. I suspect the later.

Edited June 24, 2018 by pico

[jaapv]

Visit your optician? Seriously: If a lens cannot be focussed correctly using the EVF there is something seriously wrong with the lens. If you are sure this is not user error, have it checked out by Leica.

[lct]

Back focus at f/5.6 with an EVF? Never seen this so far. I suspect you did not use image magnification. 

[BjarniM]

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Or your monitor?

Nope. My monitor is just fine.

 

If a lens cannot be focused by the electronic viewfinder, then it's gotta be whacked out beyond belief or human error. I suspect the later.

Nope. I'm not blond nor am i stupid.

 

Visit your optician? Seriously: If a lens cannot be focussed correctly using the EVF there is something seriously wrong with the lens. If you are sure this is not user error, have it checked out by Leica.

My optican is fine, and my eyes are fine as well. I might get the lens checked by Leica.

 

Back focus at f/5.6 with an EVF? Never seen this so far. I suspect you did not use image magnification.

Yes, i always use maximum image magnification when shooting portraits, and i do it the right way: I focus with the lens wide open and stop it down after i've nailed the focus and then i shoot.

[jaapv]

If you have nailed focus and the image is sharp in the EVF (magnification), it is utterly impossible that it is unsharp out of the camera, as the EVF takes its feed directly from the sensor. 

 

But - If you focus wide open and then stop down, you will run into focus shift. i.e. the plane of focus will shift with the smaller aperture. Many lenses exhibit this behaviour, the pre-FLE Summilux 35 asph, for instance, is a prime offender. Personally I don't know about the 50 APO, but it might be the case. One can find reports of a focus shift up to 10 mm on the Internet.

 

The correct procedure, if you want perfect focus, is to finetune with the EVF stopped-down.

[harryzet]

If you have nailed focus and the image is sharp in the EVF (magnification), it is utterly impossible that it is unsharp out of the camera, as the EVF takes its feed directly from the sensor. 

 

But- If you focus wide open and then stop down, you will run into focus shift. i.e. the plane of focus will shift with the smaller aperture. Many lenses exhibit this behaviour, the pre-FLE Summilux 35 asph, for instance, is a prime offender. Personally I don't know about the 50 APO, but it might be the case. One can find reports of a focus shift up to 10 mm on the Internet.

 

The correct procedure, if you want perfect focus, is to finetune with the EVF stopped-down.

 

so you have a 15.000 euro-combo, that cannot deliver sharp pictures?

[jaapv]

It can - if you use it properly as outlined above in EVF mode. 

You probably wouldn't notice using the OVF, as I suspect Leica will calibrate the lens at something between 2.8 and 4.0. 10 mm shift would be practically unnoticeable in that case, except in very critical work, like eyelash photography.

 

Price has little to do with it - a nice simple article by Zeiss:

 

https://lenspire.zeiss.com/photo/en/article/focusing-zeiss-dslr-lenses-for-peak-performance-part-one-the-challenges

[TomB_tx]

I agree it sounds like focus shift when stopping down, as shift is most obvious from wide open to f4-5.6. Stopping further and the increased DOF compensates somewhat. I have a Voigtlander 35 f1.4 that has significant shift stopping down, like the pre-asph Summilux. My sample is quite sharp, but when using on the M9 stopped to 5.6 outdoors the sharpest plane is always behind the intended focus. 

Used with live view I focus stopped down with mag view, and that works well, 

[lct]

[...] Yes, i always use maximum image magnification when shooting portraits, and i do it the right way: I focus with the lens wide open and stop it down after i've nailed the focus and then i shoot.

 

The wrong way to me but you're not alone to disagree with me . See what Jaap wrote above about focus shift. Now i've never got focus shift with my 50/2 apo i must say. Anyway, you may wish to focus at working aperture and tell us what happens afterwards.

[helged]

so you have a 15.000 euro-combo, that cannot deliver sharp pictures?

 

 

The M10+50-APO will certainly deliver very sharp and optically outstanding images when the lens and body are both calibrated. Actually, the 50-APO-M is one of the optically highest resolving, and sharpest, of the M-lenses, with smooth roll-off going into and out of the focus zone. The lens is sharp, no question about that... The beauty of the EVF is that one can check the calibration at any time and any place, although good light conditions may help: Focus on a given point/subject with the EVF at max magnification (10x) at various apertures, focus with the rangefinder only on the same point with the same apertures, sit down and examine the images at 100% in Lightroom or whatever. A perfectly calibrated camera (i.e., rangefinder mechanism) and lens will deliver equally sharp images with either methods. I have sent several lenses (and a few bodies) to Wetzlar and others due to miscalibration. A miscalibrated M-body/-system can be a frustrating experience. A calibrated system is having an instrument in your hands.

[pico]

Nope. I'm not blond nor am i stupid.

 

Well, I am stupid but at least I'm not blond!

[dugby]

Have you successfully focussed with other lenses on your M10 ?

 

Are you able to test your 50APO on a different M camera, maybe at your dealer ?

[mdemeyer]

If he describes accurately focusing wide open with the EVF but being off when he stops down, that’s focus shift, pure and simple.

[low325]

The FLE is supposed to minimize focus shift, not necessarily eliminate it.  

[jay968]

One other thing besides focus shift that I can think of and I don't think has been addressed here....are you checking what you are doing using a tripod or are you shooting hand held? It is very possible to focus hand holding the camera and then without realizing it, slightly change your position or the distance between camera and subject prior to actually clicking the shutter.

[ELAN]

@BjarniM - I nail focus almost every time with the OVF on my M10 + 50 APO at f/2.  I also use f/4 from time to time and have never seen focus shift.

Edited June 26, 2018 by ELAN

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[jeff_m]

Just take it to a Leica dealer. These things can be difficult to sort out in a forum.