Leica M - Microlenses ?

[Peter Branch]

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On his Blog Erwin Puts published the following:-

 

".......This new sensor has some unique features, the most important one being the lack of the layer of microlenses. The new sensor design makes it relatively insensitive to the effects of skew rays hitting the pixels at the outer area of the sensor and equally good results are obtained when using tele-centric or normal lens constructions......"

 

But page 22 of the Leica brocure is devoted to the very special microlenses used with the new sensor. The page has the typical number of typos associated with Leica's English language publications, (We used to think it was quaint.), but the two statements are diametrically opposed.

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[Lightwrangler]

On his Blog Erwin Puts published the following:-

 

".......This new sensor has some unique features, the most important one being the lack of the layer of microlenses. The new sensor design makes it relatively insensitive to the effects of skew rays hitting the pixels at the outer area of the sensor and equally good results are obtained when using tele-centric or normal lens constructions......"

 

But page 22 of the Leica brocure is devoted to the very special microlenses used with the new sensor. The page has the typical number of typos associated with Leica's English language publications, (We used to think it was quaint.), but the two statements are diametrically opposed.

 

The latest LFI article about the new M states the new Max-sensor has thinner electronic layers which leads to shallower pixel wells and thus less problems with skew light. But the sensor still has microlenses although they are "newly designed". Whatever that means.

According to LFI in-camera correction is still necessary, but only because of vignetting, not for color correction. The use of wideangle lenses thus should be much more convenient.

 

Mike

[thighslapper]

I'll bet sensor dust shows up something terrible as a result........

[IWC Doppel]

I'll bet sensor dust shows up something terrible as a result........

 

Dust is an interesting point. I assume we will be cleaning in the normal way, and still having to ?

[UliWer]

In a video interview with Mr. Overgaard Stefan Daniel also described the sensor as having no microlenses. There is a different structure which copes with the problems of light hitting it in different angles. He also said that this works for Leica lenses as well as other ones. If this is realized without other problems Zeiss and Voigtländer will like the new M as well.

[Lightwrangler]

In a video interview with Mr. Overgaard Stefan Daniel also described the sensor as having no microlenses.

 

I don't remember him saying so. I recall him mentioning the specially designed microlenses. Though i must admit his english was very incomprehensible in this sequence.

 

Mike

[Peter Branch]

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I don't remember him saying so. I recall him mentioning the specially designed microlenses. Though i must admit his english was very incomprehensible in this sequence.

 

Mike

 

My understanding of what was said is that the Leica M has microlenses of a new design, which is entirely consistent with Page 22 of the brochure. Also, and I think not reported elsewhere but perhaps of significance, that the new microlenses are not progressively offset relative to the pixels the further they are from the centre of the sensor as they are on M8/M9 sensors. This is again consistent with the brochure which simply shows each pixel being centered on the pixel. Much emphasis was placed on the virtues of the offset design when the M8 was launched. Now it seems it is a virtue that they are not offset.

 

It seems to me that the offset design may have offered benefits to users of the wide angle lenses sold by Leica 6 years ago but things have moved on. All new Leica wide angle lenses are of the retrofocus type, (telecentric was the word used in the interview), and I understand that the designs of many of the lenses from other manufacturers are, and actually often were, retrofocus. The performance of these lenses may well actually suffer as a result of the offsetting.

[sandymc]

I think the M9 showed that while offset microlenses are a solution for some of the problems of M glass and digital sensors, on a full-frame sized sensor they bring other problems with them. The M9 sensor has proved (in my opinion anyway) to be quite unpredictable; red edge, etc that varies with aperture, how well the lens is optically centered, etc.

 

Probably the shallower photo cells on the new sensor have allowed Leica to go back to a design that has more predictable performance, and hence is easier to correct in firmware.

 

Sandy

[Lightwrangler]

Here is a diagram that shows the differences between old and new Leica M sensor and microlenses.

 

Mike

[Peter Branch]

Here is a diagram that shows the differences between old and new Leica M sensor and microlenses.

 

Mike

 

Unfortunately this diagram does not show the feature which Stefan highlighted in the interview relating to the absence of the offset of the microlenses at the edges of the sensor in the new M sensor, unlike the M8/M9 sensors. There are other differences which the diagram does make clear but it is the offset issue to which attention was specifically drawn.

[Lightwrangler]

I think the diagrams explains the lack of microlens offset just fine. The new microlenses are much steeper thus directing light rays more vertically towards a much closer photodiode. No need to offset anything on the edges to avoid diffusion.

 

Mike

[thighslapper]

You are correct ..... And that's exactly what Daniels says. it's the thinness of the sensor that is the main difference.

[lct]

http://tinyurl.com/8kfo6l7 (page 22)

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[Peter Branch]

The picture of the "Standard CMOS sensor" ignores the fact that the Leica CCD sensor's microlenses were offset. It is not a true and accurate representation of the situation as it applies to the Leica M camera. It may be that there are no CMOS sensors with offset microlenses, but that is irrelevant

 

If the diagram is re-drawn to show an offset, a feature much publicised at the time of the launch of the M8, then the light paths are quite different and the light does not "spill" into the adjacent pixel.

 

Also of note in this diagram is that the angle of incidence of the light rays in the "Standard CMOS" is much more oblique. If the additional thickness of the "Standard CMOS" causes such a change in the angle of incidence then the focal length of the image forming lens would have to me measured in microns not mm.

 

I believe Mr. Daniel's verbal point about the benefit to image quality being derived as a consequence of the absence of any microlens offset in the new sensor is perhaps more significant than anything in the brochure. He seems like a man who knows what he is talking about and seemed keen to get this otherwise unpublicised point across to his audience.

[Lightwrangler]

Controlling diffusion by using offset microlenses is a hardware solution, impossible to influence after the sensor is finished and thus difficult to control with different lenses, even through firmware. We all saw the problems Leica had with the italian flag phenomenon et al.

 

Not having to take offset microlenses into consideration probably makes firmware control over vignetting and color correction much easier.

 

Mike

[Peter Branch]

Controlling diffusion by using offset microlenses is a hardware solution, impossible to influence after the sensor is finished and thus difficult to control with different lenses, even through firmware. We all saw the problems Leica had with the italian flag phenomenon et al.

 

Not having to take offset microlenses into consideration probably makes firmware control over vignetting and color correction much easier.

 

Mike

 

If it were established that the, (clearly possible), disadvantages of the micro-lens offseting outweighed the advantages, particularly with the very latest lens designs, then that would fully justify Mr. Daniel’s emphasis of this feature. Since it seems there are no other CMOS sensors with offset micro-lenses it can’t be a relevant point with respect to the sensors and the image quality in other manufacturers’ cameras – it must have been made with respect to previous Leica M cameras.

 

This is clearly a complex technical subject with many variables and, it seems, equally many unknowns. Marketing hype, brochure speak and typos are not helping.

 

We will just have to wait to see how the new Leica M actually performs. I'm looking forward to the day mine arrives.

[charlesphoto99]

What it appears to me is that Leica are trying to mimic the sharpness of the CCD sensor by directing the light at a more direct path. It may mean that the higher iso's are a bit noisier than Nikon/Canon, but also sharper with a more film grain like structure which to me is a better thing than the smeary lack of micro contrast one gets with the current crop of dslrs. I actually really like the look of 1600 on the M9. But only time will tell when production models are ready for image review.

[thighslapper]

The picture of the "Standard CMOS sensor" ignores the fact that the Leica CCD sensor's microlenses were offset. It is not a true and accurate representation of the situation as it applies to the Leica M camera. It may be that there are no CMOS sensors with offset microlenses, but that is irrelevant

 

If the diagram is re-drawn to show an offset, a feature much publicised at the time of the launch of the M8, then the light paths are quite different and the light does not "spill" into the adjacent pixel.

 

Also of note in this diagram is that the angle of incidence of the light rays in the "Standard CMOS" is much more oblique. If the additional thickness of the "Standard CMOS" causes such a change in the angle of incidence then the focal length of the image forming lens would have to me measured in microns not mm.

 

I believe Mr. Daniel's verbal point about the benefit to image quality being derived as a consequence of the absence of any microlens offset in the new sensor is perhaps more significant than anything in the brochure. He seems like a man who knows what he is talking about and seemed keen to get this otherwise unpublicised point across to his audience.

 

They are only offset AT THE PERIPHERY .... to compensate for the extremely oblique angles that light impacts from wide angle lenses. In the middle there is no offset. The current design requires no modification at the periphery of the sensor as the wells are shallow and adequate light strikes the photodiodes.

 

This diagram just shows the basic difference in manufacture and the optical consequences, not the explanation of why offset lenses are used in the M8/9......

 

There is no hype, no mystery, and this subject has been discussed ad nauseam on multiple other threads on the forum.......

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Hallo,

Look here: Leica M

[thighslapper]

What it appears to me is that Leica are trying to mimic the sharpness of the CCD sensor by directing the light at a more direct path. It may mean that the higher iso's are a bit noisier than Nikon/Canon, but also sharper with a more film grain like structure which to me is a better thing than the smeary lack of micro contrast one gets with the current crop of dslrs. I actually really like the look of 1600 on the M9. But only time will tell when production models are ready for image review.

 

No, they are just trying to get round a basic optical problem caused by using wide angle lenses in a body that was designed for film.....

 

The more energy you can get directly on the photodiode, the greater the output, lower the noise, and less raw image processing that is needed..... it's a simple problem of optics and optoelectonics..... this is an elegant solution

[jaapv]

If it were established that the, (clearly possible), disadvantages of the micro-lens offseting outweighed the advantages, particularly with the very latest lens designs, then that would fully justify Mr. Daniel’s emphasis of this feature. Since it seems there are no other CMOS sensors with offset micro-lenses it can’t be a relevant point with respect to the sensors and the image quality in other manufacturers’ cameras – it must have been made with respect to previous Leica M cameras.

 

This is clearly a complex technical subject with many variables and, it seems, equally many unknowns. Marketing hype, brochure speak and typos are not helping.

 

We will just have to wait to see how the new Leica M actually performs. I'm looking forward to the day mine arrives.

But the main advantage of the more precise microlenses and the shorter distance between the Bayer filter and the photosensitive sites is the reduction of crosstalk.

This is a serious disadvantage of the "deeper"standard CMos sensors, one of the reasons for the newest generation of backlit sensors.

The steeper microlenses will also concentrate the light more, giving less impact to the vignetting effect of the on-sensor circuitry.

I have a feeling the Leica sensor will be comparable to a backlit sensor in performance.