Newly bought 35SL : I was not ready for this

[jplomley]

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Anyone else notice that their 35 APO SL biases DOF in front of the plane of focus, regardless of distance. This has annoyed me since day one, especially for landscapes when stopped down to ca. f/8. Not sure of this is by design, but I somehow think not.

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[robb]

5 hours ago, jplomley said:

Anyone else notice that their 35 APO SL biases DOF in front of the plane of focus, regardless of distance. This has annoyed me since day one, especially for landscapes when stopped down to ca. f/8. Not sure of this is by design, but I somehow think not.

I think you are correct.  All of the SL apo summicrons seem to have less depth of field than similar m designs or from other manufacturers.  I’m fine with the effect for most of my work.  They act kind of like 1.4 lenses.  So if I needed tons in focus for landscape situations, I’d prob be shooting at f11.  Even the 24-90 also seems to exhibit this.
 

Robb

[helged]

10 hours ago, jplomley said:

Anyone else notice that their 35 APO SL biases DOF in front of the plane of focus, regardless of distance. This has annoyed me since day one, especially for landscapes when stopped down to ca. f/8. Not sure of this is by design, but I somehow think not.

Can't say I have noticed this on SL35 (nor on SL75 or the three first SL-zooms). Focus is based on off-sensor reading, so there can't be calibration issues involved, as far as I can tell.

Wide(ish) open, focus fall-off is sharp on SL35 and 75, but eg landscape images on f8 or thereabout have a DOF that put most of the scene in focus, as expected (pendling on focus point and difference between the closest and most remote part, clearly). 

But it could be that I havn't noticed - or searched for - DOF-biases. A 'test' could be done with eg SL35 and a 35-M from Leica, Zeiss, Voigtander, etc on SLx, carried out at identical f-stop and with focus on the same part of the image. Field curvature will show up, with SL35 being the most 'flat' lens (I believe), possibly influencing the DOF perception. 

[jplomley]

6 hours ago, helged said:

Can't say I have noticed this on SL35 (nor on SL75 or the three first SL-zooms). Focus is based on off-sensor reading, so there can't be calibration issues involved, as far as I can tell.

Wide(ish) open, focus fall-off is sharp on SL35 and 75, but eg landscape images on f8 or thereabout have a DOF that put most of the scene in focus, as expected (pendling on focus point and difference between the closest and most remote part, clearly). 

But it could be that I havn't noticed - or searched for - DOF-biases. A 'test' could be done with eg SL35 and a 35-M from Leica, Zeiss, Voigtander, etc on SLx, carried out at identical f-stop and with focus on the same part of the image. Field curvature will show up, with SL35 being the most 'flat' lens (I believe), possibly influencing the DOF perception. 

A good test for this spring! I shall compare the 35 APO SL DOF distribution at a variety of distances against my 35 Lux FLE which on my M10-R and M10M has been spot-on (i.e. no noticeable bias). 

[jplomley]

12 hours ago, robb said:

I think you are correct.  All of the SL apo summicrons seem to have less depth of field than similar m designs or from other manufacturers.  I’m fine with the effect for most of my work.  They act kind of like 1.4 lenses.  So if I needed tons in focus for landscape situations, I’d prob be shooting at f11.  Even the 24-90 also seems to exhibit this.
 

Robb

Thank-you for corroborating Rob! The APO SCs become noticeably softer as they are stopped down, so I prefer to park them at f/8 and where feasible focus stack. I have noticed when stacking that roughly 2/3 of the DOF is in front of the plane of focus. Was rather shocked the first time I noticed this, and it is regardless of distances. Never seen this with my 35 Lux FLE on the M10-R/M10M, but as mentioned above shall do a more deliberate and thorough evaluation this spring.

[Stuart Richardson]

Seems like it is worth a test. It is not something I noticed, but in going through some pictures, I think I can see what you are getting at. I am not convinced it is aberrant yet though. I do wonder, however, is this is one of the things that makes the 35mm APO Summicron separate the subjects from the background more like an f1.4 lens. I guess I also have not seen much of a detrimental effect from this, as most of my landscapes are so far away that I focus on infinity and that gets most of the frame in focus, and most of the closer in shots are ok with isolating the subject. In any case, it will be interesting to see how it is born out in a test.

[jplomley]

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Quote

 I do wonder, however, is this is one of the things that makes the 35mm APO Summicron separate the subjects from the background more like an f1.4 lens

This....my thoughts exactly! Don't get me wrong, it is a stellar lens, just need to be aware of this attribute and compensate accordingly. Really looking forward to the next SL body that will take further advantage of these APO Summicrons.

[Photoworks]

one Leica team member talked about this.

He was saying that ASPH lenses don't have a LINEAR sharpness falloff to bokeh, in real life they are designed to have a faster transition from focus to non in focus, this favor the 3D pop that they are after.

I have notice that even 24-90 has shorter in focus area at close F stop than aspected. I don't have an issue shooting at f16, CaptureOne has a Diffraction correction and sharpness adjustments in lens profile that works really well.