Stop Down MF to Avoid Focus Shift?

[agencal]

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Hi.

I realized some focus shift with SL 75mm apo cron and 90-280mm on SL2. The problem is the body always choose to AF at the widest aperture(f2 for 75mm) to get in more light for a better lcd/evf  viewing but let's say if you are shooting at f4 then there is a front focus shift.

When i was using Fuji GFX 100 their lenses also had this issue but there was a special STOP DOWN button(like dof preview) to be able to MF at the shooting aperture if critical focusing is needed.

Is there a way to do this on SL2? I just want to manuel focus with the aperture which i choose to shoot.

Best

 

Ahmed

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[Photoworks]

I use most my lenses wide open and I have not have your problem, I use spot focus most of the time and it is spot on.

I can be some setting on the camera, or operator error. I would do some test on tripod to narrow down the issue.

Suggestion. I you half press the shutter Botton you can AF, keep holding and gently touch the focusing ring, It will magnify the view to refine focus.

[SrMi]

There is no option to focus manually at working aperture with L lenses.

[caissa]

I cannot see this problem with my lenses (I also have these). I use them since they are available (several years). I used Canon and Nikon before and always found their AF not always on target (if looking into details). And the SL was a clear improvement. The SL2 was about equal.

I also use mostly spot.

 So I wonder, with the zoom where do you see this shift (which focal length ? Or simply the full range ?)

By the way on the SL you can stop down to see the working aperture. On the SL2 they did not implement it, but many complained about it and I hope it will come again with a firmware update.

In my eyes manual focus gives precise results, but focus help is not very precise (edges of sharply focused objects marked in color, called focus peaking) so I don’t use it anymore, only magnification if needed. It’s not precise enough for me and the color distracts, so I find it not useful. But magnification can be very useful to refine focus.

Edited October 17, 2020 by caissa

[Photoworks]

5 hours ago, SrMi said:

There is no option to focus manually at working aperture with L lenses.

probably because it hard to see what is in focus and the eve foes to high ISO to show the image and the noise is in the way of a clear edge.

On M lens you get more accurate focus if you focus wide open and close down to capture. L lenses would have the same effect.

In any case my focus is very precise on multiple L lenses.

[Stuart Richardson]

Ahmed,

I think your request is totally reasonable and should be something that the camera can do, even if it might cause some noise at times. Nearly all the SLR's I have used have had this option, so it is a bit odd to see it left out of a professional camera. The M lenses can be stopped way down in bright light and still be easily focused, so it should not be an issue to implement this for daylight at least, and SLR cameras would also get very dark in the viewfinders past about 5.6, and yet they still had the option. I read through the manual to see if I could find a unused setting, but could not. It seems like indeed this is not possible. It is a shame. You might consider reaching out to Leica Customer Support and perhaps they will either want to see your lens, or will add your request to the next firmware update.

Edited October 18, 2020 by Stuart Richardson

[stephanjuergenschulz]

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Leica SL cameras do compensate any possible focus shift with Leica L-Mount lenses automatically. This works as well for manual focussing. So, no need to stop down to compensate focus shift.

[SrMi]

51 minutes ago, stephanjuergenschulz said:

Leica SL cameras do compensate any possible focus shift with Leica L-Mount lenses automatically. This works as well for manual focussing. So, no need to stop down to compensate focus shift.

That sounds great. I think Hasselblad H series does that as well.

Can you point me to the documentation that talks about automatic focus-shift compensation with Leica SL/SL2?

[agencal]

14 hours ago, stephanjuergenschulz said:

Leica SL cameras do compensate any possible focus shift with Leica L-Mount lenses automatically. This works as well for manual focussing. So, no need to stop down to compensate focus shift.

Can you inform me where this information about automatic focus-shift compensation come from? 

Thanks

[stephanjuergenschulz]

Sorry for late reply.

It comes directly from Leica Productmanagement. We did realize this already for our S-System 12 years ago and it is a standard feature in Leica Autofocus camera since a long time.

Best

Stephan Schulz, Head of Productmanagement Professional Camera Systems at Leica Camera AG

[SrMi]

37 minutes ago, stephanjuergenschulz said:

Sorry for late reply.

It comes directly from Leica Productmanagement. We did realize this already for our S-System 12 years ago and it is a standard feature in Leica Autofocus camera since a long time.

Best

Stephan Schulz, Head of Productmanagement Professional Camera Systems at Leica Camera AG

What did they reply to and what did they realize 12 years ago? Thanks.

[Stuart Richardson]

I believe he meant that Leica has applied focus shift compensation to their autofocus cameras for the last 12 years. I remember hearing about this with respect to the S system, as focus shift is not an issue at all with the S lenses. Lens variations are also registered and compensated for (so the lens is measured at the factory and the body is measured at the factory and they communicate their tolerances to each other so that the focus is accurate. This is why Leica does not have AF compensation in the body...it should not be necessary. If it is, it is a sign of a bigger problem and the lens and camera should go in for service).

All that said, there are still good reasons to be able to stop down the lens. It is important to get a sense of the depth of focus and preview the actual composition of the shot. Even if the camera will accurately manually focus wide open without focus shift, it still does not allow you to easily compose a stopped down shot where you want to see the hyper focal distance. The top menu will give you distances, but I find it helpful to actually see it. I think it would be nice if there were a way to stop down the lens for focusing...more for compositional reasons than sharpness. Of course, it is possible to take a picture, but it is not quite the same. The only way to see the depth of field at the moment is to go into video mode...you could focus that way and then just hit the button to go back to photo mode I guess...