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Archive 2015 · A thinner sensor stack may be possible after all!

  
 
JT AU
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p.47 #1 · p.47 #1 · A thinner sensor stack may be possible after all!


Thanks for your informative posts relating to the Contax G21 & G28 lenses. I am planing to buy an A7R to use with the Contax G lenses and was considering the Kolari mod as well.

Is there much difference in the performance of these lenses after the Kolari mod? From what I understand the G28 is generally only useful as a B&W lens because of the magenta cast problem and I assume the same applies to the G21? Does the G21 really only work on the A7R after the M mount conversion of the lens?

I also found this Flickr member who claims to use the "lens compensation app" in the A7R to get good results with the G28. (see https://www.flickr.com/photos/davelamnet/12077246614/in/photostream/) Are any other Forum members experienced with this app? I repeat I don't yet own an A7 camera.

I would also appreciate any suggestions from forum members on other affordable wide angle film lenses that work well with the A7R assuming the contax G28 and G21 are not worth the effort.



Jun 22, 2015 at 04:49 AM
vitix68
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p.47 #2 · p.47 #2 · A thinner sensor stack may be possible after all!


For the modified A7 (not S, not R), how did you tweak the color balance. I tried sunny/cloudy/AWB (I'd like to avoid using this one too much) and different position on each grids ... I didn't manage something I can rely on yet. Do you have one position on the grid for each mode?
Thx,

Vincent



Jun 22, 2015 at 05:31 AM
beetlephoto
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p.47 #3 · p.47 #3 · A thinner sensor stack may be possible after all!


JT AU wrote:
Thanks for your informative posts relating to the Contax G21 & G28 lenses. I am planing to buy an A7R to use with the Contax G lenses and was considering the Kolari mod as well.

Is there much difference in the performance of these lenses after the Kolari mod? From what I understand the G28 is generally only useful as a B&W lens because of the magenta cast problem and I assume the same applies to the G21? Does the G21 really only work on the A7R after the M mount conversion of the lens?

I also found this Flickr member
...Show more
Having the G-Biogon 21mm, I would not recommend it on the A7rM. Purple cast, need to have f/11 for goodish corners (I have the M-mount conversion if that helps).



Jun 22, 2015 at 09:00 AM
hiepphotog
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p.47 #4 · p.47 #4 · A thinner sensor stack may be possible after all!


vitix68 wrote:
For the modified A7 (not S, not R), how did you tweak the color balance. I tried sunny/cloudy/AWB (I'd like to avoid using this one too much) and different position on each grids ... I didn't manage something I can rely on yet. Do you have one position on the grid for each mode?
Thx,

Vincent


Vincent, if you mean white balance, then doing custom WB is the way to go. Just imagine you are using an astro-modified cam or a full spectrum cam, those guys have to use custom WB as well for normal photography. Personally, since the A7 series has 3 custom WB settings, I set one for sunny, one for cloudy, and one for indoor. Other situations, I have my ExpoDisc handy.



Jun 22, 2015 at 10:20 AM
hiepphotog
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p.47 #5 · p.47 #5 · A thinner sensor stack may be possible after all!


JT AU wrote:
Thanks for your informative posts relating to the Contax G21 & G28 lenses. I am planing to buy an A7R to use with the Contax G lenses and was considering the Kolari mod as well.

Is there much difference in the performance of these lenses after the Kolari mod? From what I understand the G28 is generally only useful as a B&W lens because of the magenta cast problem and I assume the same applies to the G21? Does the G21 really only work on the A7R after the M mount conversion of the lens?

I also found this Flickr member
...Show more

The G21 might be worth it if you are okay with shooting at f/11 only for landscape, or not too demanding with corner-to-corner sharpness, especially at mid- to close distance. I love the color rendition of the G21. Comparing between stock and Kolari mod, there is a significant improvement, though not enough; on a stock cam, even at f/11, you don't get usable corners or edges. For optimal result, you need to have a distance scale to know your exact focus point.

The G28 is the same (only a slight improvement in the edges and corners). However, being a narrower focal length, it has less DOF and thus it's more difficult to get optimal result.

Keep in mind that if your concern is only for the color cast, it's an easy problem to solve. Even on a Leica M camera, you still have to deal with severe color cast and vignette. I have not used the app since I would rather fix the problem myself (either via Flat field LR plugin or just careful photoshop). And the best way would be to get the A7s. This cam is so good at handling the vignette and color cast that I have not had to deal with any color cast problem so far, even when I shot with the G21 or Elmar 24 or the ZM 15.

I believe the ZM 21/25 might be a better option since they were designed with a little more telecentric (longer and bigger). From what I've seen, the Ricoh GR 21/3.5 might be a good option as well. On the DSLR side, just pick any 21 and 28 you like (Zuiko OM is nice and small enough, etc.). Nonetheless, the ultimate is still the (Super) Elmar series.



Jun 22, 2015 at 10:34 AM
gyoung143
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p.47 #6 · p.47 #6 · A thinner sensor stack may be possible after all!


I am using the lens compensation app on a standard A7 to cope with the corner colourcasts and light fall off from a 21/2.8 Elmarit asph and the 15mm Heliar.

The 21 gives excellent results sooc at 8 and 11

Gerry




Jun 22, 2015 at 11:19 AM
mdemeyer
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p.47 #7 · p.47 #7 · A thinner sensor stack may be possible after all!


Another shot from the Voigtlander 15mm Series III on the A7M (added to the A7M Flickr group).

Disorientation

Slight crop, probably to an effective 18mm. I'm liking it more and more. :-)

Michael



Jun 23, 2015 at 12:47 AM
JT AU
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p.47 #8 · p.47 #8 · A thinner sensor stack may be possible after all!


OK thanks for the replies. WRT the contax G28 is any improvement gained on the A7R by cutting the black plastic 'tabs' off at the rear of the lens?

I have an M-rokkor 28mm and will just try that first. I will also look for some Pentax SMC M WA lenses, from reading the various threads the SLR film camera lenses generally offer better performance than range finder film lenses as I am sure you all know already



Jun 26, 2015 at 06:58 PM
hiepphotog
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p.47 #9 · p.47 #9 · A thinner sensor stack may be possible after all!


JT AU wrote:
OK thanks for the replies. WRT the contax G28 is any improvement gained on the A7R by cutting the black plastic 'tabs' off at the rear of the lens?...


I certainly couldn't spot any difference between w/ and w/o rear guards before the mod.




Jun 27, 2015 at 12:37 PM
pinholecam
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p.47 #10 · p.47 #10 · A thinner sensor stack may be possible after all!


Finally sent in my A7.
It was supposed to be Apr1, but was delayed by the filter stock issue sure to a fire at Schott.

It will be a month before I get it back and I can then compare results on my brother's A7 and the modded camera.



Jul 03, 2015 at 04:07 PM
bjornthun
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p.47 #11 · p.47 #11 · A thinner sensor stack may be possible after all!


hiepphotog wrote:
Vincent, if you mean white balance, then doing custom WB is the way to go. Just imagine you are using an astro-modified cam or a full spectrum cam, those guys have to use custom WB as well for normal photography. Personally, since the A7 series has 3 custom WB settings, I set one for sunny, one for cloudy, and one for indoor. Other situations, I have my ExpoDisc handy.


On a full spectrum modified camera you can use a Schott BG38 filter on the lens to get back to a normal colour response from the camera.

Does the thin filter mod on the sensor alter the colour response enough for AWB not to work?

How is the infrared response of a thin filter modded camera? Is there any IR contamination? A B+W 486 filter on the lens should solve any IR contamination issue, just like on the Leica M8.



Jul 03, 2015 at 08:18 PM
JimBuchanan
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p.47 #12 · p.47 #12 · A thinner sensor stack may be possible after all!


bjornthun wrote:
On a full spectrum modified camera you can use a Schott BG38 filter on the lens to get back to a normal colour response from the camera.

Does the thin filter mod on the sensor alter the colour response enough for AWB not to work?

How is the infrared response of a thin filter modded camera? Is there any IR contamination? A B+W 486 filter on the lens should solve any IR contamination issue, just like on the Leica M8.


It would be nice to get a response from Kolari Vision on this.



Jul 03, 2015 at 11:03 PM
Tariq Gibran
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p.47 #13 · p.47 #13 · A thinner sensor stack may be possible after all!


The risk of uneven color response (not just overall Wb via a gray card for instance) is one of the main things which has prevented me from doing the conversion on my main camera. Pretty much all posted images I have seen with the mod exhibit evidence of uneven color respose. I suspect a very good custom profile is needed for any critical color work (much more so than with an unmoderated sensor).


Jul 04, 2015 at 08:00 AM
hiepphotog
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p.47 #14 · p.47 #14 · A thinner sensor stack may be possible after all!


bjornthun wrote:
On a full spectrum modified camera you can use a Schott BG38 filter on the lens to get back to a normal colour response from the camera.

Does the thin filter mod on the sensor alter the colour response enough for AWB not to work?

How is the infrared response of a thin filter modded camera? Is there any IR contamination? A B+W 486 filter on the lens should solve any IR contamination issue, just like on the Leica M8.


It's best to contact Ilija on this matter. Though from my conversation with him, he tried to maintain the original UV-IR cut-off ability of the stock filter. FWIW, the ability of a BG38 to block out UV-IR is proportional to the thickness of the filter. So by simply using the BG38 does not guarantee the same color response as the stock camera for a full spectrum. I did a histogram comparison between the stock and modded cam, there is certainly a shift in color channels under fixed WB. As for IR contamination, it has not been obvious to me, maybe because I have not looked for it. Overall, I have no regret doing the mod, and I would send my next Sony body (either the A7RII or A9) to Ilija as soon as he figures out how to mod the next gen body.



Jul 04, 2015 at 09:11 AM
mdemeyer
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p.47 #15 · p.47 #15 · A thinner sensor stack may be possible after all!


bjornthun wrote:
On a full spectrum modified camera you can use a Schott BG38 filter on the lens to get back to a normal colour response from the camera.

Does the thin filter mod on the sensor alter the colour response enough for AWB not to work?

How is the infrared response of a thin filter modded camera? Is there any IR contamination? A B+W 486 filter on the lens should solve any IR contamination issue, just like on the Leica M8.


Guys,

This is discussed at length earlier in the thread, including some suggested adjustments to the color balance settings using the in-camera settings. My experience, based on the original mod with the BG38 glass, is that there is a slight shift in white balance, but I have not had any problems correcting it in post. (I process from RAW so adjust WB in post anyway.) I originally planned to develop a custom profile for the camera, but have not found it to be necessary so have not made the effort. The AWB settings can be tweaked with the in-camera adjustments enough to get very close and, let's face it, AWB is rarely perfect anyway.

Remember that the glass was changed a few months back to one with better long-term humidity resistance, which is what is used today. I don't remember if Kolari Vision has made a public statement of what glass is used in the current modifications, so I'll not state it here since they have invested a lot in this project and I see no reason to give that information to potential competitors.

Regarding IR leakage, the replacement glasses were chosen to have similar IR rejection characteristics as the standard Sony filter, even with the thinner filter taken into account. I don't remember hearing anyone complain about IR leakage issues, and I have not seen any. I think the original BG38 filter passed a little more UV than the stock filter, but I use UV filters so have never seen any issue and, again, have not heard anyone else comment negatively on it.

I think one area for improvement, which was an issue with the stock A7 filter too, is A/R coating to reduce reflections in the filter under extreme conditions. I have seen that when shooting low-light architectural shots that included bright light sources (for example, in the wine storage caves at Del Dotto winery recently). I've discussed this with Ilija and he has identified a source to have the filters coated, but needs a high enough volume commitment to make that economically practical. Unfortunately, at the moment this remains a fairly specialized and low-volume activity.

Michael



Jul 04, 2015 at 06:39 PM
JT AU
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p.47 #16 · p.47 #16 · A thinner sensor stack may be possible after all!


Thanks for the replies again. Can anyone comment on the performance of the ZM 21mm f/2.8 on the A7r mod? Is it too soft in the corners? I have looked through the entire thread and even though references are made to this lens there are no tests posted. I do appreciate the experience that has been shared with other M mount rangefinder lenses! JT


Jul 04, 2015 at 09:13 PM
JaKo
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p.47 #17 · p.47 #17 · A thinner sensor stack may be possible after all!


mdemeyer wrote: 'My experience, based on the original mod with the BG38 glass, is that there is a slight shift in white balance...'


I feel this helping thread is slipping into a defending state for the mod itself and for Kolari Vision.
Let's put it this way, no mods are without compromises; whether you mod you ride, boat, stereo or your own body there are always pros & cons.
In case of Kolari thin sensor stack mod, shooters who wanted to use wider angle RF lenses on Sony bodies got what was previously impossible at slight expense of altering post processing work. Was the AWB perfect/correct before on stock A7x cameras? WB is fairly easily to correct using general in-camera settings or PP (as Michael pointed out, all was already discussed on 47 pages) but corner smearing, unlikely.

For RF lenses the mod is definitely an improvement over stock A7x, no questions about it. If you fear to lose your camera warranty, re-tweak AWB settings, alter your PP or alike than this alternative is not for you.



Shot with Kolari modded WA RF lens:
http://www.kozera.ca/photos/images/_DSC9821_1600.jpg



Jul 04, 2015 at 09:22 PM
sootyvrs
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p.47 #18 · p.47 #18 · A thinner sensor stack may be possible after all!


Hi all new to the forum..

I'm very much interested in the thin sensor mod to my Sony A7S but unfortunately have not been able to go through all 47 pages of discussion.

I reside in the UK and just wanted to know if Kolari are the only company to offer this service? I was hoping that someone in the UK can do this mod?

I have read that it can take around 2 months to get my camera back if I send it in which is not an option for me so may consider buying a camera from Kolari already modified and then selling mine privately?

I currently use the CV15 III which I have no problems with smearing or colour casting but my other lenses 35 & 50 lux, the corners are not good until I stop down to around f4 for the 35 and f5.6 for the 50. Not usualy a problem when I shoot wide open as most of the corners maybe out of focus anyhow but have found that softness comes into the image from outside 1/3 of the frame..

I considered getting an M240 and had a demo using my lenses and noticed that the corners were better albeit still not perfect but not sure if this was more to do with field curvature of the lenses and perhaps using focus recompose? I'm still on the fence with going this route or perhaps getting the mod on the A7x

If I'm going to change bodies, I may also consider moving to the mark2 body but read that this is not possible yet?

Anyone else have this mod done from UK?



Jul 19, 2015 at 05:40 AM
pinholecam
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p.47 #19 · p.47 #19 · A thinner sensor stack may be possible after all!


My A7 came back with a very fast 3 week turn around time.
Very fast, since I am in Singapore.
1wk to get to Kolari, 1 wk modification, 1 wk return to me.

The service is certainly very good.


I am also interested in how the mod has improved my SLR lenses, so here are some tests with the Pentax K24/2.8
Full sized images are also on my Flickr.


Full Image

A7_standard Pentax K24 f2.8 at f10 by jenkwang, on Flickr


Center Crop

A7_standard Pentax K24 f2.8 at f10-center by jenkwang, on Flickr


A7K Pentax K24 f2.8 at f10-center by jenkwang, on Flickr


Left Crop

A7_standard Pentax K24 f2.8 at f10-left by jenkwang, on Flickr


A7K Pentax K24 f2.8 at f10-left by jenkwang, on Flickr


Right Crop

A7_standard Pentax K24 f2.8 at f10-right by jenkwang, on Flickr



A7K Pentax K24 f2.8 at f10-right by jenkwang, on Flickr


There is certainly an improvement to me.

My thanks for everyone here for all the information that has been shared here.



Jul 19, 2015 at 09:59 AM
Steve Spencer
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p.47 #20 · p.47 #20 · A thinner sensor stack may be possible after all!


pinholecam wrote:
My A7 came back with a very fast 3 week turn around time.
Very fast, since I am in Singapore.
1wk to get to Kolari, 1 wk modification, 1 wk return to me.

The service is certainly very good.

I am also interested in how the mod has improved my SLR lenses, so here are some tests with the Pentax K24/2.8
Full sized images are also on my Flickr.

Full Image
https://farm1.staticflickr.com/484/19624712438_68967b8a95_h.jpg
A7_standard Pentax K24 f2.8 at f10 by jenkwang, on Flickr

Center Crop
https://farm1.staticflickr.com/484/19624697020_137afdd1e4_o.jpg
A7_standard Pentax K24 f2.8 at f10-center by jenkwang, on Flickr

https://farm1.staticflickr.com/270/19786548496_d8ba22334e_o.jpg
A7K Pentax K24 f2.8 at f10-center by jenkwang, on Flickr

Left Crop
https://farm1.staticflickr.com/562/19624697110_c00b35956b_o.jpg
A7_standard Pentax by jenkwang, on Flickr

https://farm1.staticflickr.com/478/19817544061_9c3c519d40_o.jpg
A7K Pentax K24 f2.8 at f10-left by jenkwang, on Flickr

Right Crop
https://farm4.staticflickr.com/3746/19624715018_c21c2ef4b6_o.jpg
A7_standard Pentax K24 f2.8 at f10-right by jenkwang, on Flickr

https://farm1.staticflickr.com/339/19624683388_6f9fc6fe08_o.jpg
A7K Pentax K24 f2.8 at f10-right by jenkwang, on Flickr

There is certainly an improvement to me.

My thanks for everyone here for all the information that has been shared here.
...Show more

Very nice demonstration of the improvement that can be seen in the corners with even an SLR lens.


Jul 19, 2015 at 12:53 PM
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