Is it better to focus with Visoflex at open aperture?

[Krisch64]

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Closed working apertures are known to have a larger range of sharpness depending on the focal length. I also see this in the Visoflex and the display. Depending on the aperture, the focus peaking then shows me a larger area of sharpness.

Now I have two questions:

•  When I check the finished image in the camera display, at full magnification the edges of the area of sharpness that I expected for the selected aperture according to the lens marking no longer appear properly sharp to me. Am I mistaken or does this mean that I cannot rely on the full depth of field range per aperture according to the lens marking? Does the sharpness in the depth of field range visibly decrease towards the edges?
• Therefore, when focusing in the Visoflex, should I return to open aperture for full subject sharpness and then return to working aperture after focusing?

Thank you for your help, Dietmar

[Simone_DF]

43 minutes ago, Krisch64 said:

Therefore, when focusing in the Visoflex, should I return to open aperture for full subject sharpness and then return to working aperture after focusing?

You can, but there's no need for that.

Instead of relying on focus peaking, which is unreliable, especially on a clunky low quality one like the Visoflex, I suggest to magnify the image to 100% at your working aperture and check if it's sharp where you want it.

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[SrMi]

27 minutes ago, Simone_DF said:

You can, but there's no need for that.

Instead of relying on focus peaking, which is unreliable, especially on a clunky low quality one like the Visoflex, I suggest to magnify the image to 100% at your working aperture and check if it's sharp where you want it.

IMO, the most precise focusing can be achieved with focusing wide open, using magnification and focus peaking. In magnified view, the edges of target object should become red only when exactly in focus.

[Tailwagger]

Sadly, in my view, there is no singular answer to your question. As I demonstrated here, there are circumstances when focus peaking with the lens stopped down is pretty much useless. As a general methodology, what works for me regardless of focal length, is to set the camera to auto-zoom magnify, focus initially with the RF and then move my eye to the EVF while the image is still zoomed to confirm focus accuracy.  If one is working with a longer lens wide open, it's a quick way to confirm that focus was nailed. If not its a quick adjust. If, OTOH, the lens is stopped down significantly, the scene is low light or I'm using a wide angle with generically deeper DoF, the RF is the better bet to guarantee you are good and I merely rely on the EVF or framing accuracy. 

 

[jaapv]

DOF is the  gradual acceptable range of unsharpness around the sharp focal plane. Which means that the edges are unsharp and just acceptable - or not, depending on the judgement of the photographer, subject, contrast, final print size, cropping, etc. If you get your critical focus spot-on using the rangefinder, you are doing nothing wrong and just running into the limitations of zone (mis!)focus. The DOF scale dates back to the 1930ies and is too wide by at least one stop for digital photography and even more for larger prints and crops. Zone focus has been largely replaced by AF and is mostly applicable to some manual focussing photography

[Tailwagger]

With all this talk of Mevfs, peaking and M lenses on the SL, just for fun yesterday I took the SL2 with the 75mm 'lux along.  Given all these discussions around focusing while open or stopped down, I paid particular attention to this aspect of usage.  In the end, I concluded (really simply reminded myself) that even with a longer lens I find I am far better off acting as a surrogate for auto-aperture.  It was very simple to prove this to myself by simply focusing on a target at 5.6 or 8, flipping the aperture open and re-zooming in on the target via the back button on the SL2. It was quite obvious that my primary focusing target was most times missed, often IMO unacceptably so. This was exactly the case, I attached below.

Of course, there's the reply of 'what difference will it make if you're reasonable close, just not perfect and well within the DoF?'. Often, very little. But just as I mentioned with wides, if one is intent on ensuring that focus target in the near field is as sharp as possible and is stopping down to limit the amount of falloff into the background, IMO, nailing the center of the CoC is crucial.  A brief example from yesterday.

This shot was one of those disastrous/providential moments, depending on your PoV, where the rising sun was directly behind and above the subject, the shadow cast by the building was insufficient to prevent flare and the shooting angles where very limited.  It was obvious that the result was naturally going to wind up low contrast and washed out, which given the subject material, I was happy to exploit.  I felt however, it was crucial to ensure sharpest possible focus on the subject's eyes, which were perhaps 3-4 meters away, while limiting the amount of falloff of the building so that enough detail was preserved to compliment the subject.  My initial focus on the headlamps, done at f8, was soft when viewed a f1.4, so I corrected it. The treatment is naturally a little noisy, but hopefully it conveys the notion of moments when the focus point is relatively critical to ensure that the primary target is the sharpest spot in the frame. 

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SL2 Summilux 75mm F8 1/800"