Kolari Ultra Thin sensor mod. Nikon Z6 with M mount lenses

I decided to build a kit with M mount lenses and full frame mirrorless camera primary for its compact size and image quality. Since I already have invested in the Nikon DSLR system, I also wanted it to work with my telephoto zooms and macro lenses. I could just have bought a digital Leica M camera and kept my D810 and be done with it, but then I would obviously need two camera bodies and - what's more important - no Leica M camera has built-in image stabilization, so to me the better choice is and was to get the Nikon Z6 since it will do the double duty well. (I don't need the extra resolution the Z7 provide.)

After a good long consideration, I decided to go all in and get the Z6 modified to work the best with M mount lenses. I now have a Kolari Vision Ultra Thin sensor modified Z6. As the name suggests, Kolari has removed the stock sensor glass and put an extremely thin (0.2mm) hot mirror filter without anti aliasing filter in its place. This means the total sensor glass stack thickness is about that of a digital Leica M camera.

My tests so far show that from an optical point of view, it's improving the performance of the M lenses significantly. On the stock Z6 I needed to mod the lenses slightly by adding a small piece of paper on the lens mount to get the plane of focus completely parallel with the sensor. Most would need it on one side, but one needed it on the opposite side. This was also the case with my full spectrum converted Sony a7. In other words, both a too thick and a too thin sensor glass required a tiny swing of the lens. With the UT mod, the plane of focus is within limits: Adding a piece of paper (one tenth of a millimeter or so) on either side will decrease overall sharpness in the sides.

The issues with wide angle M mount lenses on mirrorless cameras is well documented, but to my pleasant surprise the UT mod improvements even includes the longer lenses like the 90mm Apo-Summicron-M. This may of course in part be because the AA filter is gone, but nevertheless the improvement is there.

The below image is shot with the 90mm Apo-Summicron-M wide open. To see the 24MP image in 100%, click and open it.

Trees in snow is a resolution torture test, so honestly, I am very happy with the result.


Leica 90mm Apo-Summicron-M @ f/2.0 on Kolari UT mod. Nikon Z6

Since I use the Megadap MTZ11 AF adapter, I get the relevant EXIF data in the file. Note, however, that the MTZ11 always "tells" the camera that it's an f/1.4 G type lens that is mounted.

Quite the interesting undertaking and way to go on the success. How much for the sensor mod and do they also convert to IR if so desired? Can you still use Nikon glass?

Very promising results. I've been thinking about getting a Z6 as a mirrorless alternative to a M body.

I wonder if your modification gives better results than a unmodified Z7?

Also I was under the impression that the lens resolution should outperform a 24 Mpixel sensor with or without modification?

Not that I do not like your experiment.

Ernie Misner said:

Quite the interesting undertaking and way to go on the success. How much for the sensor mod and do they also convert to IR if so desired? Can you still use Nikon glass?

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Yes to all questions!

However, UT and IR mod are different mods.

The price for the UT conversion on Nikon Z cameras is $500 plus shipping.

WalterH said:

I wonder if your modification gives better results than a unmodified Z7?

Also I was under the impression that the lens resolution should outperform a 24 Mpixel sensor with or without modification?

Not that I do not like your experiment.

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A UT modded Z6 will perform much better than an unmodified Z7. It will not have 45MP of course, but the sensor glass thickness will make a big difference outside the center. The UT modded Z6 may actually behave slightly better than a UT modded Z7 regarding color shift towards the corners since the pixels are larger.

Regarding lens resolution, all M mount lenses will perform better on a UT modded Z6 since the anti aliasing is removed. I even think a UT modded Z7 will perform better than a stock Z7, particularly with wide angle lenses.

Leica 28mm Summicron-M Asph v2 @ f/2.0 on the Nikon Z6 with Kolari UT sensor mod. No lens profile, no vignetting correction. Just white balance correction and moderate sharpening (as in image in the first post).

I see no color shift, no chromatic aberrations and practically no field curvature.


Leica 28mm Summicron-M Asph v2 @ f/2.0 on Nikon Z6 with Kolari UT sensor mod.

Thanks for your info.

I prefer the clean look with so little noise of the Z6 over the Z7. Still the Z7 delivers more resolution with a good lens and proper use.

I do wonder however, just how much the improvement of the modification is in direct comparison. If I use for example the Nikkor Z 50mm F1.8 S lens on the Z6II i get the impression on pixel peeping that the resolution is close to perfect for the pixel density of the Z6. I am not certain though what can be learned from a better method of testing than just looking at high magnification on a good screen. I know some will be lost due to the anti alias filter but just how much seems difficult to quantify as I learned years ago from discussions of D800 versus D800E.

WalterH said:

Thanks for your info.

I prefer the clean look with so little noise of the Z6 over the Z7. Still the Z7 delivers more resolution with a good lens and proper use.

I do wonder however, just how much the improvement of the modification is in direct comparison. If I use for example the Nikkor Z 50mm F1.8 S lens on the Z6II i get the impression on pixel peeping that the resolution is close to perfect for the pixel density of the Z6. I am not certain though what can be learned from a better method of testing than just looking at high magnification on a good screen. I know some will be lost due to the anti alias filter but just how much seems difficult to quantify as I learned years ago from discussions of D800 versus D800E.

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You are welcome.

My impression - without a direct and thorough test - that the improvement in resolution is visible in the entire frame. Some of this will be the lack of AA filter, but I also suspect that the thinner glass may add to this.

The point of getting the Kolari UT mod is using your Nikon Z (or whatever full frame mirrorless you convert) with Leica M mount (and legacy SLR) lenses. Note that Nikon Z lenses are designed for the stock glass thickness, so you may lose image quality with (at least some of) the Z lenses. So far I have seen that field curvature might be exaggerated with for instance my Mitakon Speedmaster 85mm f/1.2 lens as well as some M mount lenses when compared to the stock sensor glass.

On the other hand, I have the Laowa 9mm FF RL in Z mount which is available in both Z and M mount (as well as Sony E and Canon R) and it performs much better with the UT mod than stock. I saw quite a bit of LaCA with the stock sensor glass and this is gone with the UT mod.

To me, getting the ultra-thin sensor glass mod is totally worth it. Not only for M mount lenses, but also the improvement I see when using even long DSLR lenses caused by the lack of AA filter.

The most notable drawback is that the UT filter doesn't cut as much red color as the stock which makes trouble with the white balance when shooting in incandescent lighting, particularly if it's a bit dimmed. I have bought a couple of blue color correction filters for this, but it's not needed if halogen lamps aren't dimmed.

Well yes if you do own only a few Leica lenses the cost of the Z6 body plus modification becomes a minor investment.

Besides the optical performance of some Leica lenses a Z6 with only a thin adapter and a Leica lens makes a very compact camera. And it is easy to use the Zikon Z bodies as basic camera in manual mode. When needed the now very exact AF system (with third party adapter) maybe a welcome addition to manual focus, even assisted MF when desired.

Quite a nice combo.

WalterH said:

Well yes if you do own only a few Leica lenses the cost of the Z6 body plus modification becomes a minor investment.

Besides the optical performance of some Leica lenses a Z6 with only a thin adapter and a Leica lens makes a very compact camera. And it is easy to use the Zikon Z bodies as basic camera in manual mode. When needed the now very exact AF system (with third party adapter) maybe a welcome addition to manual focus, even assisted MF when desired.

Quite a nice combo.

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I feel the need to say that it's about M mount lenses, not only from Leica, but also Voigtländer and Zeiss. In addition to this there are quite a few new Chinese brands that make M mount lenses of varying quality. Voigtländer has made some gorgeous new M mount lenses recently that rival the super expensive Leica offerings.

I do have Leica lenses in both 90mm and 28mm (bought used at very good prices), but my 50mm, 15mm and (now sold) 21mm are Voigtländer lenses. The Nokton 50mm f/1.2 Asph VM is simply stellar and not expensive for what it is, and it is ridiculously tiny for a 50mm f/1.2 lens.

I consider $500 plus shipping a good investment since the Z6UT can shoot both with my Nikon F autofocus telezoom and macro lenses as well as work flawlessly with the M mount lenses. The alternative would be to have two camera bodies; one for M mount lenses and one for Nikon F mount lenses. A used Leica M240 body would cost me more than three times, if not four times, as much as the Kolari UT mod, and no Leica M body has in-body image stabilization. So, in my book it makes sense to get this mod if M mount lenses is what you want to carry.

LarsHP said:

WalterH said:

Well yes if you do own only a few Leica lenses the cost of the Z6 body plus modification becomes a minor investment.

Besides the optical performance of some Leica lenses a Z6 with only a thin adapter and a Leica lens makes a very compact camera. And it is easy to use the Zikon Z bodies as basic camera in manual mode. When needed the now very exact AF system (with third party adapter) maybe a welcome addition to manual focus, even assisted MF when desired.

Quite a nice combo.

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I feel the need to say that it's about M mount lenses, not only from Leica, but also Voigtländer and Zeiss. ....

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Yes Zeiss lenses made me follow your thread. I may have this wrong from memory but I expected my 21mm Distagon F2.8 to be better wide open than what I get today on my Z6II and Z7 but looking back everything might be better in the old days.

Funny thing is that at F8 it is stellar. So much better that I think something is wrong with the interaction of this lens with the sensor wide open.

I am no expert but can imagine that certain filter in front of the sensor may have detrimental effect wide open but not so at smaller apertures or vice versa.

WalterH said:

LarsHP said:

WalterH said:

Well yes if you do own only a few Leica lenses the cost of the Z6 body plus modification becomes a minor investment.

Besides the optical performance of some Leica lenses a Z6 with only a thin adapter and a Leica lens makes a very compact camera. And it is easy to use the Zikon Z bodies as basic camera in manual mode. When needed the now very exact AF system (with third party adapter) maybe a welcome addition to manual focus, even assisted MF when desired.

Quite a nice combo.

Click to expand...

I feel the need to say that it's about M mount lenses, not only from Leica, but also Voigtländer and Zeiss. ....

Click to expand...

Yes Zeiss lenses made me follow your thread. I may have this wrong from memory but I expected my 21mm Distagon F2.8 to be better wide open than what I get today on my Z6II and Z7 but looking back everything might be better in the old days.

Funny thing is that at F8 it is stellar. So much better that I think something is wrong with the interaction of this lens with the sensor wide open.

I am no expert but can imagine that certain filter in front of the sensor may have detrimental effect wide open but not so at smaller apertures or vice versa.

Click to expand...

If the 21mm Distagon is a SLR lens designed for film (not digital), the UT mod may improve its performance, at least compared to a stock digital FF Nikon/Canon/Sony camera.

Two, or two and a half, millimeters of glass in front of the sensor and light coming in at a steep angle => lateral chromatic aberrations and smearing (if the lens was designed for film).

Yes it is an old design. It is ZF2 but nothing was changed in the optics.

This is why I got it so cheap used but even if it is only "almost excellent" wide open it makes little difference for me I can use it at 5.6 or 8 any time.

It outperformes the Z6 at F5.6. For the Z7 I am happy with F8. I have not tested my Zeiss Macro Planar 100mm F2.0 in detail. At that focal length I expect a small if any negative effect but I will test this anyway.

So far I am happy with the Nikkor Z lenses otherwise I would consider the modification, depending on other peoples experince. It could easily make things worse.

WalterH said:

Yes it is an old design. It is ZF2 but nothing was changed in the optics.

This is why I got it so cheap used but even if it is only "almost excellent" wide open it makes little difference for me I can use it at 5.6 or 8 any time.

It outperformes the Z6 at F5.6. For the Z7 I am happy with F8. I have not tested my Zeiss Macro Planar 100mm F2.0 in detail. At that focal length I expect a small if any negative effect but I will test this anyway.

So far I am happy with the Nikkor Z lenses otherwise I would consider the modification, depending on other peoples experince. It could easily make things worse.

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If it's a native ZF.2 lens, then I think it's designed for DSLRs, and you should see it perform as well as it can - at least on your Z7. This also implies that the UT mod shouldn't make that lens perform better - apart from the removal of the AA filter on your Z6.

Hello Lars,

Thanks for your post, nice to hear first-hand experience with Kolari mod on a Nikon Z camera.

Most of the other posts in the web are focused on Sony a7 series.

I'd be interested to know about any improvement with vintage Nikkor glass wide open: a reduced sensor stack thickness should increase sharpness and focus shift with film era Nikkor D F 1.4 or F 2 lenses, for example.

Long flange distance of Nikon F mount imposed quite long nodal distance for older, pre-digital era Nikkors, so I'm expecting a very good performance with minimal corner smearing, much better than with classic DSLRs.

Can you confirm? Any samples?

Regards

Simone

tjshot said:

Hello Lars,

Thanks for your post, nice to hear first-hand experience with Kolari mod on a Nikon Z camera.

Most of the other posts in the web are focused on Sony a7 series.

I'd be interested to know about any improvement with vintage Nikkor glass wide open: a reduced sensor stack thickness should increase sharpness and focus shift with film era Nikkor D F 1.4 or F 2 lenses, for example.

Long flange distance of Nikon F mount imposed quite long nodal distance for older, pre-digital era Nikkors, so I'm expecting a very good performance with minimal corner smearing, much better than with classic DSLRs.

Can you confirm? Any samples?

Regards

Simone

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Hi Simone,

Unfortunately I had to return the camera to Kolari Vision since the IBIS wasn't working after the conversion, so I can't comment much at the moment. It should be on the way back to me now, so I will test more and see. That said, I don't have any vintage Nikon F lenses. I do have a Mitakon Speedmaster 85mm f/1.2 and the field curvature seems to have increased visibly on that lens. The lens was designed for digital, so the decreased glass thickness is probably the reason there. If the lens was made for film, it might have been the other way around (creating reverse field curvature).

LarsHP said:

tjshot said:

Hello Lars,

Thanks for your post, nice to hear first-hand experience with Kolari mod on a Nikon Z camera.

Most of the other posts in the web are focused on Sony a7 series.

I'd be interested to know about any improvement with vintage Nikkor glass wide open: a reduced sensor stack thickness should increase sharpness and focus shift with film era Nikkor D F 1.4 or F 2 lenses, for example.

Long flange distance of Nikon F mount imposed quite long nodal distance for older, pre-digital era Nikkors, so I'm expecting a very good performance with minimal corner smearing, much better than with classic DSLRs.

Can you confirm? Any samples?

Regards

Simone

Click to expand...

Hi Simone,

Unfortunately I had to return the camera to Kolari Vision since the IBIS wasn't working after the conversion, so I can't comment much at the moment. It should be on the way back to me now, so I will test more and see. That said, I don't have any vintage Nikon F lenses. I do have a Mitakon Speedmaster 85mm f/1.2 and the field curvature seems to have increased visibly on that lens. The lens was designed for digital, so the decreased glass thickness is probably the reason there. If the lens was made for film, it might have been the other way around (creating reverse field curvature).

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Please do post an update when you get the camera back. I'm interested in the resolution of this situation since I'm considering this mod myself. Obviously, losing stabilization on z6 wouldn't be good.

Most of my Nikon are film-era lenses, which seem to perform fine on DSLRs, but I'm interested in possibly improving performance with a UT conversion.

Interesting. Would you expect the same improvements with Leica R-glass? I did once convert my 35mm f2.8 Elmarit-R for use on a D700, but was not happy with the result and converted back again. I was thinking about trying again with a Z7, which would only involve an adapter, not mount conversion, since I have some other Leica-R lenses besides. I had thought that perhaps the AA filter was the problem with the D700, but I had not considered glass thickness. Thank you for your time.

labalaba said:

Interesting. Would you expect the same improvements with Leica R-glass?

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In my experience, Leica R lenses don't need the mod, because they aren't as symmetrical.

labalaba said:

I did once convert my 35mm f2.8 Elmarit-R for use on a D700, but was not happy with the result and converted back again. I was thinking about trying again with a Z7, which would only involve an adapter, not mount conversion, since I have some other Leica-R lenses besides. I had thought that perhaps the AA filter was the problem with the D700, but I had not considered glass thickness. Thank you for your time.

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