M lens performance on the SL

[jaapv]

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I don't think a microlens could deflect light over more than an adjacent sensel.

If light were deflected by a microlens into the "wrong photo site" then you would still have full resolution, just shifted to the adjacent sensel. If instead the microlenses had problems only with some light frequencies (internal refraction), you would see the classical color-vignetting (but the A7R2 has none).

Add the fact that the smearing effect is similar on all A7 sensors, regardless of sensor resolution, and the fact the Kolari mod greatly improves the performance without touching the microlenses.

If there is crosstalk due to  the incidence angle and microlens design, it means that the light is spread over more than one sensel, not that the light is shifted in its entirety. dependent on the direction of the incoming light, a sensel may exhibit crosstalk with two adjacent sensels.

The removal of (parts of) the filter array will reduce the  refraction, diffraction  and CA caused by the filter glass. Replacing the Bayer Filter by clear glass would reduce the optical effects of the filter stack (considerably) more, see the Monochroms.

In other words, if your quest is for more resolution from Leica M lenses, the M typ 246 is the way to go if you want to remain in the Leica range.

 

I still fail to see what the use of  taking one aspect out of the total concept of a camera and declaring that paramount  is.

If very high resolution, regardless of the drawbacks, is your one and only criteria for the success of your photography,  you are in the wrong place with Leica. By all means buy a camera from a maker who chose a different compromise. But trying to declare your preferences universal time and time again is bound to wear the patience of your audience thin.

[edwardkaraa]

If there is crosstalk due to  the incidence angle and microlens design, it means that the light is spread over more than one sensel, not that the light is shifted in its entirety.

The removal of (parts of) the filter array will reduce the  diffraction  and CA caused by the filter glass.

I think you meant refraction, Jaap

 

So basically, cover glass thickness causes corner smearing, light angle incidence causes vignetting and color shading (both remedied with shifted microlenses, and/or BSI sensor architecture that allow for a better light ray acceptance.

Edited November 11, 2015 by edwardkaraa

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[jaapv]

Both, It was lost in an edit. Thanks.

On modern sensors it is more the optical design of the microlenses than shifting them.

[jonoslack]

I think you meant refraction, Jaap

 

So basically, cover glass thickness causes corner smearing, light angle incidence causes vignetting and color shading (both remedied with shifted microlenses, and/or BSI sensor architecture that allow for a better light ray acceptance.

Hi Edward

i just think that if the issues were that discreet the results with the Sony would be more linear and predictable ( as they are with the SL and the M). Smearing seems to me to be different from Softness (which the SL shows a little more than the M).

 

We all want to put things in neat little boxes, but experience tells me that issues interact, sometimes causing unexpected and unintended results)

[edwardkaraa]

Hi Edward

i just think that if the issues were that discreet the results with the Sony would be more linear and predictable ( as they are with the SL and the M). Smearing seems to me to be different from Softness (which the SL shows a little more than the M).

 

We all want to put things in neat little boxes, but experience tells me that issues interact, sometimes causing unexpected and unintended results)

Of course, Jono, it's much more complicated than that. But I am personally more interested with the final results rather than the causes, but it's nice to chat about them

 

As mentioned by someone earlier, the inconsistencies seen on the A7 bodies may be due to different lens designs. Floating elements for instance will affect the exit pupil of the lens as it is focused at far or close distances. The smearing is mostly caused by astigmatism while the softness is caused by field curvature. Both are caused by the cover glass, and both coexist together to varying degrees depending on the lens design and the cover glass characteristics. It could be that the Sony glass has a higher refractive index, on top of its extra thickness. Or maybe Leica resorted to a low RI glass to preserve the performance of M lenses. So indeed, it's a quite complicated issue

Edited November 11, 2015 by edwardkaraa

[k-hawinkler]

I would like to suggest there is a difference between corner smearing and residual softness of the lens once smearing has been eliminated.   

[edwardkaraa]

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I would like to suggest there is a difference between corner smearing and residual softness of the lens once smearing has been eliminated.

That goes without saying

[k-hawinkler]

That goes without saying

 

I am glad we agree on that point.  Thanks. :-)

 

[edwardkaraa]

I am glad we agree on that point. Thanks. :-)

But we do agree on most points

[jonoslack]

I would like to suggest there is a difference between corner smearing and residual softness of the lens once smearing has been eliminated. 

I think there is a difference before smearing has been eliminated too

[k-hawinkler]

I think there is a difference before smearing has been eliminated too

Yup, you are right, I agree.

Smearing looks one way.

Veiling haze another, distinctly differently.

[ramarren]

I would like to suggest there is a difference between corner smearing and residual softness of the lens once smearing has been eliminated. 

 

For sure. That's why a good test to determine the quality of the sensor match includes a reference frame made with the same lens in an R body on low-grain film. That, to me, is the reference against which performance of any R lens on a digital body must be compared. 

 

It was doing those comparisons that was when I became dissatisfied with the R lenses on A7, and much more appreciative of their performance on the M-P. The M-P preserves to a noticeably greater degree the native optical character of the lenses. Which is not to say that what they produced looked bad on the A7, it just didn't look the way I expected. I bought these lenses for their specific rendering qualities, and a well-matched digital sensor must preserve that. 

[svenjosh]

Hi Edward

i just think that if the issues were that discreet the results with the Sony would be more linear and predictable ( as they are with the SL and the M). Smearing seems to me to be different from Softness (which the SL shows a little more than the M).

 

We all want to put things in neat little boxes, but experience tells me that issues interact, sometimes causing unexpected and unintended results)

 

 I think that the very short Flange distance of the Sony A7 series contributes in part to smearing and color cast. That is why we should evaluate the lens and camera as a package. I am sure leica SL sensor is better optimised for the M lenses than Sony.

 

 I am not into sensor mods. The kolari mod improves the results but still not even close to M240 or M9. On the flip side, kolari mod affects colors when using native lenses. So its not the ideal situation for me.

 

I am really interested in the performance of Leica 21 sem and summarits. They are part of my smaller kit if I do not want to lug around the Luxs

[jaapv]

Quite impossible as the register distance cannot be different between the Sony and the Leica. The difference in flange distance is taken up by the adapter.

 

I think that the very short Flange distance of the Sony A7 series contributes in part to smearing and color cast

[k-hawinkler]

Quite impossible as the register distance cannot be different between the Sony and the Leica. The difference in flange distance is taken up by the adapter.

 

 

+1.  Thanks Jaap. 

[svenjosh]

Quite impossible as the register distance cannot be different between the Sony and the Leica. The difference in flange distance is taken up by the adapter.

 

 

Shorter Flange distance requires steeper angle. The sensor is optimised for this and the Sony Fe lens design.  Mechanically moving the rear element away by 1 cm (approx.) by an adapter for M lens does not equate optimal angulation of light rays reaching the sensor. As I mentioned it just may be part of the reason, I am not sure. But cannot be dismissed either, even though it give K-hawinkler great joy

[jaapv]

Sorry, the distance between the M lens and the sensor is identical on a Sony and a Leica. Thus the angle is identical. Think of it this way: the adapter brings the flange forward.

Yes - Sony/Zeiss lenses and Sony cameras are optimized together. However, you will not be able to use such a lens on an M, so that point is moot.

[svenjosh]

Sorry, the distance between the M lens and the sensor is identical on a Sony and a Leica. Thu the angle is identical.

 

 But the sensor in Sony is optimised for different angle  than a Leica M lens.

[edwardkaraa]

But the sensor in Sony is optimised for different angle than a Leica M lens.

Indeed but quite the opposite of what you are saying. It is optimized for telecentric lenses.

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[jaapv]

svenjosh, on 11 Nov 2015 - 17:24, said:svenjosh, on 11 Nov 2015 - 17:24, said:

 But the sensor in Sony is optimised for different angle  than a Leica M lens.

That should only work to the advantage of M lenses, as the greater distance creates a smaller angle, assuming a similar amount of telecentricity.

The whole point is that the M lenses, being heritage lenses (except some new designs) have not been designed with this aspect in mind, the Sony lenses (by need) have, and the Sony sensor (and firmware) is not optimized for this type of lens. And why should it be?