Thin sensor cover glass modification for the A7II

[ErikKaffehr]

Hi,

Kolari Vision offers a modfication for the A7II, replacing the sensor cover glass. This improves image quality with large baem angle Leica lenses. Jim Kasson has a couple of excellent articles on the issue:

Kolari Vision thin-stack mod on a7II — Zeiss 35mm/2 Biogon-M | The Last Word

Sony A7 Series Thin Filter Legacy Lens Upgrade - Kolari Vision

Best regards
Erik

 

[mbroomfield]

Thanks Erik, good to hear that Ilija has resolved the conversion with the A7II. I'm really hoping though that the A7rII won't need this.

 

[Vivek]

Hi,

Kolari Vision offers a modfication for the A7II, replacing the sensor cover glass. This improves image quality with large baem angle Leica lenses. Jim Kasson has a couple of excellent articles on the issue:

Kolari Vision thin-stack mod on a7II — Zeiss 35mm/2 Biogon-M | The Last Word

Sony A7 Series Thin Filter Legacy Lens Upgrade - Kolari Vision

Best regards
Erik

Hi, AFAIK, the conversion does NOT involve the sensor cover glass replacement.
They replace the UV/IRcut/AA filter stack with a thin BG filter and get rid of the dust shaker. The original clear sensor cover glass is still there. That is why the Biogon does not perform a as well as it does on a Leica M camera.

 

[ErikKaffehr]

Hi,

I would think it will be needed. Sony uses around 2 mm of optical glass in front of the sensor, which is pretty normal for digital cameras.

Leica uses much thinner, like 0.5 mm. So Sony lenses are optimized for 2 mm while Leica needs much thinner.

Some Leica lenses work great, many suffer from astigmatism caused by thick cover glass.

I would not expect that Sony would optimize their system for Leica glass.

Best regards
Erik

Thanks Erik, good to hear that Ilija has resolved the conversion with the A7II. I'm really hoping though that the A7rII won't need this.

 

[Vivek]

Sony use varying thickness of glass in the optical path in their cams. ~1.5mm (NEX-5N) to 2.5mm (A7); both measured. No uniform standards at all.

 

[ErikKaffehr]

Hi,

Well both are about 2mm. The out point that you need check optical thickness (thickness multiplied by index of refraction I think)

Sony use varying thickness of glass in the optical path in their cams. ~1.5mm (NEX-5N) to 2.5mm (A7); both measured. No uniform standards at all.

Best regards
Erik

 

[ErikKaffehr]

Hi,

This is the original article at LensRentals: http://www.lensrentals.com/blog/2015/01/a-thinner-sensor-stack

This is a corner image at f/2 on a Zeiss Biogon 35/2

While this one from the Loxia 35/2, same design but tweaked for the A7-series

Here is the article comparing Loxia and Biogon:
http://3d-kraft.com/index.php?optio...son-review&catid=40:camerasandlenses&Itemid=2

Now, my take is that Sony probably keeps the sensor cover glass around 2 mm, they won't make it as thin as possible, which Leica did on the M9. So, sendsor glass induced change in astigmatims would be little affected I assume.

Vignetting and crosstalk would probably be better on the A7rII. Indeed 3D-kraft has tried out an A7rII with an extreme wide angle and it showed some promise, base on the backside LCD. He was not allowed to use an own SD-card.

Best regards
Erik

Thanks Erik, good to hear that Ilija has resolved the conversion with the A7II. I'm really hoping though that the A7rII won't need this.

 

[Vivek]

Hi,

Well both are about 2mm. The out point that you need check optical thickness (thickness multiplied by index of refraction I think)






Best regards
Erik

No. The lens rental stuff is full of errors. I pointed that out to Roger et al already. Confusing piece of $&$(.

 

[ErikKaffehr]

Hi,

Calling a well researched article a piece of $&$( is not very informative, especially as you don't state which article you refer to (as there are around four on the issue). Neither do you mention what issues you have with any of those articles.

I am a bit surprised at your posting, as the effects Roger and Brian Caldwell describe are well known, glass behind the lens causes astigmatism on lenses having large beam angles.

Kolarivision gives some details about their conversion here: http://kolarivision.com/product/sony-a7-series-thin-filter-legacy-lens-upgrade/

Best regards
Erik

No. The lens rental stuff is full of errors. I pointed that out to Roger et al already. Confusing piece of $&$(.

 

[Vivek]

Hi,

Calling a well researched article a piece of $&$( is not very informative, especially as you don't state which article you refer to (as there are around four on the issue). Neither do you mention what issues you have with any of those articles.

I am a bit surprised at your posting, as the effects Roger and Brian Caldwell describe are well known, glass behind the lens causes astigmatism on lenses having large beam angles.

Kolarivision gives some details about their conversion here: Sony A7 Series Thin Filter Legacy Lens Upgrade - Kolari Vision

Best regards
Erik

I have measured the thicknesses that i mention and Roger has not, neither has Brian. This has been communicated to Roger et al as well.

BTW, the original posting of Brian Caldwell (photo.net) on the ills of thicker glass stack is well known and my post has no contradictions with that.

 

[ErikKaffehr]

Some info from Jim Kasson on the Kolari modification

Hi,

Jim Kasson, who seems to be a real scientist and a very nice guy, has published a series of observations on the Kolari modification on the A7.

Kolari Vision thin-stack mod on a7II — 28mm Elmarit-M | The Last Word

Just to say, the Kolari modification mostly reduces the astigmatism induced by the optical assembly in front of the sensor. It doesn't solve a lot of other issues. On the other hand it seems that the back side illuminated sensor of the A7rII reduces some of those other issues significantly.

So A7rII with future Kolari modifications may perform well with classical wide angle designs that have large beam angles.

Best regards
Erik

 

[iiiNelson]

Re: Some info from Jim Kasson on the Kolari modification

Hi,

Jim Kasson, who seems to be a real scientist and a very nice guy, has published a series of observations on the Kolari modification on the A7.

Kolari Vision thin-stack mod on a7II — 28mm Elmarit-M | The Last Word

Just to say, the Kolari modification mostly reduces the astigmatism induced by the optical assembly in front of the sensor. It doesn't solve a lot of other issues. On the other hand it seems that the back side illuminated sensor of the A7rII reduces some of those other issues significantly.

So A7rII with future Kolari modifications may perform well with classical wide angle designs that have large beam angles.

Best regards
Erik

Maybe it's just me but I would stick to the RF lenses that work well on all bodies, SLR lenses, native FE lenses, or get a Leica M if size is the most important factor. It seems like a tiring and ongoing exercise for some going into year 2 of FE availability. It's nothing against Kolari Vision (I use their lens filters for IR photography) but the constant complaints of sensor cover glass/sensor not being optimized for RF lenses is becoming a futile topic at every FE body release. It's not a problem Sony NEEDS to "fix" but rather an issue photographers need to work around through alternative lens/camera options. It's sort of like when people complain about the size of FF lenses. Either get a camera with a smaller sensor for those occasions you need it or buy a camera system you can live with.

 

[hiepphotog]

Re: Some info from Jim Kasson on the Kolari modification

Maybe it's just me but I would stick to the RF lenses that work well on all bodies, SLR lenses, native FE lenses, or get a Leica M if size is the most important factor. It seems like a tiring and ongoing exercise for some going into year 2 of FE availability. It's nothing against Kolari Vision (I use their lens filters for IR photography) but the constant complaints of sensor cover glass/sensor not being optimized for RF lenses is becoming a futile topic at every FE body release. It's not a problem Sony NEEDS to "fix" but rather an issue photographers need to work around through alternative lens/camera options. It's sort of like when people complain about the size of FF lenses. Either get a camera with a smaller sensor for those occasions you need it or buy a camera system you can live with.

Even though I'm a Kolari user, I agree with you wholeheartedly. People are just asking for the moon. I'm glad Kolari is here to offer this service and Sony is on top of their game with all these fabulous cameras. I have made a deliberate choice of shooting M-mount lenses on a Sony body, and I'm willing to pay more just to make it worked to my liking. In the end, it's more enjoyable to go out and shoot than spending my energy to complain.

 

[Vivek]

Re: Some info from Jim Kasson on the Kolari modification

Maybe it's just me but I would stick to the RF lenses that work well on all bodies, SLR lenses, native FE lenses, or get a Leica M if size is the most important factor. It seems like a tiring and ongoing exercise for some going into year 2 of FE availability. It's nothing against Kolari Vision (I use their lens filters for IR photography) but the constant complaints of sensor cover glass/sensor not being optimized for RF lenses is becoming a futile topic at every FE body release. It's not a problem Sony NEEDS to "fix" but rather an issue photographers need to work around through alternative lens/camera options. It's sort of like when people complain about the size of FF lenses. Either get a camera with a smaller sensor for those occasions you need it or buy a camera system you can live with.

I am not sure it is "tiring". It is good to keep in mind that their NEX-7 showed color shifts with their own "system" lenses that got taken care of (to some extent) in a NEX-6. Sure enough, the sensor cover glass stack thickness is half in 6 over that of the 7.

It is actually tiring and expensive to find the right camera that behaves as expected.

I actually bought FE lenses (35/2.8, few samples; 24-70/4, 2 samples, 28/2 one sample) and just have the 28/2. Not interested in their huge offerings and/or the ones with dubious QC.

I hope Sony take note and improve.

 

[ErikKaffehr]

Re: Some info from Jim Kasson on the Kolari modification

Hi,

Sony quality control is an issue entirely different from cover glass issues. Also, cover glass only affects astigmatism, I would think. Vignetting and crosstalk are sensor vs. lens issues.

I would also say that the 24-70/4 may not be a really very good lens, in test reports it used to be quite mediocre.

Best regards
Erik

I am not sure it is "tiring". It is good to keep in mind that their NEX-7 showed color shifts with their own "system" lenses that got taken care of (to some extent) in a NEX-6. Sure enough, the sensor cover glass stack thickness is half in 6 over that of the 7.

It is actually tiring and expensive to find the right camera that behaves as expected.

I actually bought FE lenses (35/2.8, few samples; 24-70/4, 2 samples, 28/2 one sample) and just have the 28/2. Not interested in their huge offerings and/or the ones with dubious QC.

I hope Sony take note and improve.