Inaccurate Focusing M Lenses on the SL

[SteveSFO]

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Just want to make sure the lenses are 6-bit coded.  I attached a 50 Noct f/1 today and found the images slightly out of focus.  Forgot it was not 6 bit coded and I had to enter the profile in the camera.

[jaapv]

6 bit coding has nothing to do with focus.

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[IkarusJohn]

6 bit coding has nothing to do with focus.

 

 

No, but it has everything to do with Auto-ISO settings. 

 

If you're going to make offhand remarks, Jaap (perhaps unintentionally), at least pay attention. 

Edited January 30, 2016 by IkarusJohn

[jaapv]

No, but it has everything to do with Auto-ISO settings. 

 

If if you're going to make offhand remarks, Jaap (perhaps unintentionally), at least pay attention. 

 

found the images slightly out of focus.

Thus. There is nothing about auto-ISO in the post I responded to.

[IkarusJohn]

Just want to make sure the lenses are 6-bit coded.  I attached a 50 Noct f/1 today and found the images slightly out of focus.  Forgot it was not 6 bit coded and I had to enter the profile in the camera.

 

 

There's nothing about focus in Steve's post. 

 

The inference, obvious inference, surely, is that he had his Auto-ISO settings at minimum shutter speed of 1/2f. Without the coding, in aperture priority, the camera was not raising the ISO to maintain an acceptable shutter speed. Hence, motion blur. 

 

Who said anything about focus?

 

Your post followed Steve's quoted above. You had no quote in your post. 

[jaapv]

Huh? Out of focus = auto-ISO? Or even motion blur?

Steve said out of focus...barking up trees comes to mind

[AlanJW]

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I suspect camera movement could have been the original problem, and it is possible the shutter speed dropped too low, especially if you are using ISO 50 as your base.  I say this from experience because I am finding the SL slightly more difficult to handhold than my M.  Perhaps it is because of increased weight.  However, I can focus quite sharply -- at least from what the EVF is showing and end up with images just slightly not sharp.  On closer analysis it is due to my not holding the camera steady enough at low speeds.  I am pretty good down to 1/15 with an M, but I am finding that I am not so good with the SL at that speed.

 

And how does auto ISO have anything to do with this?  Because if you have set a minimum speed of 1/f for a 50mm lens, then your minimum set on the SL will be 1/50 as it scales up the ISO to maintain the speed.

 

Last, if you were used to shooting an f/2 lens wide open in "A" mode on an M at native ISO 200, if you shot the exact same thing on an SL but at its native ISO 50, you will lose 2 stops, or in "A" mode, two shutter speed increments.   So in my example. if I am shooting an M with a 50mm f/2 wide open and the camera sets a shutter speed of 1/60, it is easy to hand hold, while if I pick up my SL with the same M lens (but ISO 50), the shutter speed will drop to 1/15, which is not so easy to hand hold.  Having developed my own sense of what the camera was doing with my M, I rarely even had to look at what the shutter speed was.  The comfort zone on the SL is different, and I am therefore thinking of changing my default ISO to 200 so as to avoid this.

 

Now I obviously do not know if this was the problem faced by the OP or whether he had a defective system, but this has been my experience,  FWIW.

[IkarusJohn]

Oh, I see.  Sorry, Jaap. You were pointing out to Steve that he said "out of focus" when he should have said the images weren't as sharp as he would have liked. 

 

Right. So, not really related to the point he was making. Just correcting his terminology. Got it. 

 

I have also noticed that in Auto ISO setting, the camera holds to ISO 50 right down until the shutter speed becomes marginal. This would be fine if 50 was genuinely base ISO, but I'm beginning to doubt that. It looks a little soft to me. 

 

I'm considering setting ISO at 100 or 200 and making my own adjustments from there. Maybe I'm being a little anti-Auto. I will also look at changing the base ISO, if I can work out how to do it. 

Edited January 30, 2016 by IkarusJohn

[LocalHero1953]

Trouble is, if we have an auto option and it works well in a lot of circumstances, we're tempted to leave it on by default. But expecting the camera to know exactly what combination of ISO, T & A is what we want in any given circumstances is asking a bit much - too many degrees of freedom.

 

Base ISO: when the SL came out it was said that base ISO was 100, and 50 was a very good Push ISO. I haven't seen problems with ISO 50, but I haven't looked hard.

[Jared]

I have also noticed that in Auto ISO setting, the camera holds to ISO 50 right down until the shutter speed becomes marginal. This would be fine if 50 was genuinely base ISO, but I'm beginning to doubt that. It looks a little soft to me. 

 

I'm considering setting ISO at 100 or 200 and making my own adjustments from there. Maybe I'm being a little anti-Auto. I will also look at changing the base ISO, if I can work out how to do it. 

 

 

I don't understand.  Whether 50 is base ISO or is a pull ISO, what does that have to do with things looking a little soft at 50?  If it's a pull, it will just have a little less dynamic range since highlights won't be quite as recoverable.  It should have nothing to do with resolution, accutance, contrast, or anything that would cause images to look "soft".

 

Feel free to use ISO 100 or 200 if you prefer, of course.  Not trying to discourage that. Just don't understand your particular comment.  Also, I'm pretty sure there is no way to change what the camera interprets as "base" ISO.  

 

- Jared

Edited January 30, 2016 by Jared

[IkarusJohn]

Trouble is, if we have an auto option and it works well in a lot of circumstances, we're tempted to leave it on by default. But expecting the camera to know exactly what combination of ISO, T & A is what we want in any given circumstances is asking a bit much - too many degrees of freedom.

 

Base ISO: when the SL came out it was said that base ISO was 100, and 50 was a very good Push ISO. I haven't seen problems with ISO 50, but I haven't looked hard.

 

 

It just looks a little soft to me. Maybe I'm being too critical, and there's a good chance any softness is from poor technique on my part. 

 

I've looked at the Auto ISO settings, and you don't seem to be able to set the minimum ISO (which seems an oversight) - which means everything will be take at 50, unless the light is so low that you need a shutter speed slower than 1/2f at ISO50. 

 

Jared, I'm sure you're right. But in practice, ISO50 looks soft to me. Perhaps "soft" is the wrong word, but it does looks as crisp ...

[DezFoto]

It's not possible for the camera to miss-focus a manual focus lens. WYSIWYG, but the OP may be mistaking contrast with focus (EVF's and rear screens can exaggerate contrast, giving the illusion of a sharp image).  

 

I haven't used the SL yet, but I have used various other EVF equipped cameras and focus can be difficult to see correctly because you are limited by the contrast and resolution of the EVF itself. Although the SL has a very high resolution EVF, it's still only a fraction of the resolution of your actual image, so pixels from the sensor are being averaged when they are displayed in the EVF. The only way to guarantee you are seeing perfect focus is to be able to see a 1:1 pixel to pixel representation. This is why we use live view tethering for product photography in the studio. Additionally, focus peaking can lead you astray as well, I generally avoid it, though it does work better if you're looking at a black and white readout instead of color (old camera operator trick), it's still not reliable enough for high resolution images.  

 

I would try different diopter settings, as someone else suggested and failing there, a different lens adaptor. If the lens adaptor is not perfectly machined it may be impossible to focus correctly with your M lenses because it's projecting the point of focus either fore or aft of the sensor. This is why cine cameras have adjustable back focus.  

[AlanJW]

Oh, I see.  Sorry, Jaap. You were pointing out to Steve that he said "out of focus" when he should have said the images weren't as sharp as he would have liked. 

 

Right. So, not really related to the point he was making. Just correcting his terminology. Got it. 

 

I have also noticed that in Auto ISO setting, the camera holds to ISO 50 right down until the shutter speed becomes marginal. This would be fine if 50 was genuinely base ISO, but I'm beginning to doubt that. It looks a little soft to me. 

 

I'm considering setting ISO at 100 or 200 and making my own adjustments from there. Maybe I'm being a little anti-Auto. I will also look at changing the base ISO, if I can work out how to do it. 

The "base ISO" cannot be changed, but I have created a preset that I use as my default that uses ISO 200.    If you set the minimum shutter speed at 1/focal length, you will can shoot down to ISO 50 in auto ISO at about 1/f (1/60) with a 50mm lens.  But I think you can set the minumum speed at a constant 1/60 also, which should suffice.

[steppenw0lf]

I am using mainly R and M lenses with the SL and I am very happy with the sharpness or in focus of the resulting images.

This does not mean that most are sharp (on the contrary, I am now much more critical and throw away more than ever).

 

But I cannot imagine a difference between the viewfinder and the end result, as both are coming from the same sensor.

 

In order to give luck a chance I do in some critical cases a sort of "bracketing" by moving a bit my upper body or my head with camera, without refocusing, and this way I'm doing several takes that are slightly "different". This changes slightly the distance and sometimes also slightly the selected angle or frame.

 

My eyesight is far from perfect (wearing glasses), so even if I wanted I could probably not tell in lifeview and in real-time if an image is really exactly in focus (whatever that means).

Maybe this is "Pfusch" (sloppy), but currently I am happy as a hatter with my SL.

 

(But I produce a lot of garbage, but so what ? Does it matter with digital storage ?)

But maybe you work differently, always with a tripod ?

 

Stephan