Zeiss Hologon 16/8 vignettes less on M10 than with M9. Why?

[raid]

I can see why the M8 has much less vignetting than the M9 because of the 33% crop, but how is the sensor in the M10 different from the snesor in the M9 to show less vignetting with the Hologon (with its filer used)?

Is it the thickness of the glass that covers the sensor or is it the sensor or is it both factors?

 

[raid]

In general, how do the two sensors differ other than one being 18MP and one 24MP?

 

[Darthfeeble]

Better micro positioning of the pixels?

 

[Bill Blackwell]

... how is the sensor in the M10 different from the sensor in the M9 to show less vignetting with the Hologon (with its filer used)? ...

I don't really know, but my first thought is that it has to do with how the M lens profiles instruct each camera as to the lens you're using. I'm assuming you're using a WATE preset on both cameras? The latest firmware on the M10 is better adjusted; at least that'd be my guess.

 

[raid]

Better micro positioning of the pixels?

This is quite possible. The M10 is a newer camera.

 

[raid]

I don't really know, but my first thought is that it has to do with how the M lens profiles instruct each camera as to the lens you're using. I'm assuming you're using a WATE preset on both cameras? The latest firmware on the M10 is better adjusted; at least that'd be my guess.

Yes, I set as profile WATE in both cameras.

 

[farlymac]

You might find some clues here, Raid. https://www.digicamdb.com/compare/leica_m10-vs-leica_m9/

Here is an interesting blog post about the two cameras. https://www.streetsilhouettes.com/home/2019/7/29/the-myth-of-the-leica-m9-ccd-vs-cmos-sensors

PF

 

[Rob-F]

I think the Leica sensors have the little lenses over the pixel sites offset, so as to capture the angular light rays and redirect them into the individual pixel receptors. I'm pretty sure all digital M sensors are like that, but it must be that they made them work even better for the M10. Progress, you know.

 

[Godfrey]

All sensors have a microlens array to help collect and focus the light falling on them into the right part of the photosite well for efficient use of the light energy. The difference between the M9 and later M sensor is that the M9 has the typical spherical microlenses of most cameras. The later Ms deviated from that—specifically to assist in handling short mount register lenses—by introducing parabolic microlenses which allow redirection of light at greater off-axis angles compared to the spherical micro lenses.

This proves to be an effective solution at a lower cost than the offset microlens array that others have tried. It's much easier to manufacture a regular array of microlenses with parabolic lenses than the ultra precise positioning required of an microlens array with offset lens positions. It's also a more general solution, as the ray trace from an offset array has to be tuned and optimized for a particular focal length range where a centrally located lens with a parabolic shape will redirect the ray of light from a greater acceptance angle and is less sensitive to the incident angle.

G

 

[raid]

You might find some clues here, Raid. https://www.digicamdb.com/compare/leica_m10-vs-leica_m9/

Here is an interesting blog post about the two cameras. https://www.streetsilhouettes.com/home/2019/7/29/the-myth-of-the-leica-m9-ccd-vs-cmos-sensors

PF

Thanks a lot! Both links are very useful. I just realized (from link 1) that my M10 has a spot meter. I never really checked this out.

 

[raid]

I think the Leica sensors have the little lenses over the pixel sites offset, so as to capture the angular light rays and redirect them into the individual pixel receptors. I'm pretty sure all digital M sensors are like that, but it must be that they made them work even better for the M10. Progress, you know.

Thanks, Rob. The later M cameras have most likely better systems in them.

 

[raid]

All sensors have a microlens array to help collect and focus the light falling on them into the right part of the photosite well for efficient use of the light energy. The difference between the M9 and later M sensor is that the M9 has the typical spherical microlenses of most cameras. The later Ms deviated from that—specifically to assist in handling short mount register lenses—by introducing parabolic microlenses which allow redirection of light at greater off-axis angles compared to the spherical micro lenses.

This proves to be an effective solution at a lower cost than the offset microlens array that others have tried. It's much easier to manufacture a regular array of microlenses with parabolic lenses than the ultra precise positioning required of an microlens array with offset lens positions. It's also a more general solution, as the ray trace from an offset array has to be tuned and optimized for a particular focal length range where a centrally located lens with a parabolic shape will redirect the ray of light from a greater acceptance angle and is less sensitive to the incident angle.

G

Quite interesting. Thank you Godfrey.

 

[phofseth]

I am not familiar with the adapted contax Hologon, but the Hologon I once had for my M3 used a concentrically graduatet "verlauf-filter" which totally neutralized the built in optical vignetting. So even if there is some correction of light loss through acute angle entry into the photosite well, there may still be the usual wide angle "cosine" light loss which the computer should correct for.

p.

 

[Godfrey]

I am not familiar with the adapted contax Hologon, but the Hologon I once had for my M3 used a concentrically graduatet "verlauf-filter" which totally neutralized the built in optical vignetting. So even if there is some correction of light loss through acute angle entry into the photosite well, there may still be the usual wide angle "cosine" light loss which the computer should correct for.

p.

The Contax Hologon 16/8 T* when new came with a similar matched, radially gradient neutral density filter as well. I don't know whether Raid has it.

G

 

[raid]

The Contax Hologon 16/8 T* when new came with a similar matched, radially gradient neutral density filter as well. I don't know whether Raid has it.

G

I have used this filter on each of my images with this lens. It works well with film, but the results look different on a digital M camera.

 

[Rob-F]

I have used this filter on each of my images with this lens. It works well with film, but the results look different on a digital M camera.

Possibly because the digital M bodies already compensate for light loss at the edges by the positioning of the microlenses? Does the filter seem like overkill with the M cameras?

 

[raid]

Possibly because the digital M bodies already compensate for light loss at the edges by the positioning of the microlenses? Does the filter seem like overkill with the M cameras?

No, there still exists vignetting in the corners. DAG had the lens coded, and he advised me to set the lens detection to auto.

 

[Rob-F]

So, maybe the closest available code isn't optimum for the Hologon?

 

[raid]

So, maybe the closest available code isn't optimum for the Hologon?

I have tried setting the lens detector manually to 16mm too.

 

[Godfrey]

The problem is simply that the Hologon 16 optical formula is not ideal for digital sensors ... The lens design was computed for 35mm film cameras. The primary nodal point is too close to the sensor and creates a ray trace too far off orthogonal to work best at corners and edges. Different sensors have different stacks of lenses and filters in their configuration so the results vary between the different digital M series sensors.

As I said before, the M typ 240 and later sensors are fundamentally different from the M9 sensor, with parabolic shaped microlenses instead of spherical shaped ones. Leica does not use offset rows of lenses, they use the micro lenses shape to help reduce issues with the short mount register. But there are limits to the adaptation, and the Hologon 16 is such an extreme design it is no wonder that there are some issues.

I doubt there's anything you can do about it.

G