p.28 #1 · A thinner sensor stack may be possible after all!
Steve Spencer wrote:
The disadvantages of the modification includes four things IMO:
First, more dust problems. It disables the dust shaker and the thinner cover glass will show the dust more easily. This means that the sensor will have to be cleaned more often as dust bunnies will be more common and more problematic.
Second, more potential IR contamination of images. The thinner cover glass will have more difficult block IR light and one can expect at times to see a bit of IR contamination.
Third, the cover glass may be more prone to damage. The glass the Kolari is using is known to degrade somewhat in high humidity environments. Kolari has been great about promising to fix sensors if they degrade, but it is a concern. The thinner glass might be more prone to cracking too and that together with the extra cleaning that will be required worries some people. Personally, I am not too worried about this issue but I am sure concerns will vary.
Fourth, lenses designed for the thick cover glass might not perform as well. I am betting (literally, Charlie and I have a six pack of beer on it) that certain lenses like the Loxia 35 f/2 will not perform as well on the modified cameras as they do on the unmodified cameras. As with lenses designed for film on the thick sensor, wide angles with short exit pupils and wide apertures should fare the worst. So a lens like the FE 55 f/1.8 is likely to be pretty good as it seems to have a long exit pupil, but a lens like the Loxia 35 f/2 that is a wider angle and has a shorter exit pupil may not do as well. If wider angle short exit pupil lenses are made, then these are likely to show the biggest problem....Show more →
Hi Steve, thanks for summarizing this! I found a few of the points you mentioned but not all of them.
(1) Dust: wouldn't be an issue for me - I had one of my DSLRs converted to infrared, which also removed the dust shaker. I am cleaning this sensor often with my Arctic Butterfly - same as I do it with my A7R (unmodified).
(2) Not too worried about this, but it is something to keep in mind.
(3) I don't think this is an issue either.
(4) Could be a dealbreaker for me - I am using all kind of glass on my A7R other than just rangefinder lenses. So far I managed well in post processing to correct for vignetting and purple color casts with my wide angle rangefinder lenses.
p.28 #2 · A thinner sensor stack may be possible after all!
mdemeyer wrote:
Short summary:
Positives
- Closer to as-designed performance for lenses designed for film or Leica digital sensor stack. That's the big win for most of the interested parties. This is true for ALL film lenses (rangefinder and SLR) although the amount of improvement varies with lens design. Again, see the technical work on the Lens Rentals blog for the science. Everything we have seen so far seems to match theory. I have not seen anyone post something that showed a degradation with a film lens vs. the unmodified Sony A7-series cameras, and many of the results are very, very positive.
- It appears (and I think the jury is still out on this) that the mod has a minimal negative impact on the native lenses. Theory predicts there should be some negative impact, but so far I have not seen anyone present clear evidence.
Negatives
- Thinner glass makes dust more visible because it's closer to the sensor. Same issue as Leica.
- Dust shaker disabled (it's attached to one of the thick glass elements on the stock Sony and that glass is removed).
- Camera warranty is void by modification.
- Current filter is Schott BG39. It seems that (virtually?) all BG filter glass can be damaged by long-term exposure to humidity, worse when combined with high temperature. BG39 is middle of the pack in resistance to this (better than the S8612 used by Leica in the M9, but worse than some other possible, but difficult to source, glass types). KolariVision is providing a replacement warranty against glass corrosion, but some people in tropical locations have decided against the mod on this issue.
- Thinner glass is easier to break while cleaning the sensor. Similar to Leica in this regard.
There are other topics under discussion but still not clear in my mind.
- Sensor reflections. This was an issue with the original A7, and reported to be better with the A7r and A7s. It's not clear how the modified cameras are in this regard. I can cause reflections if I really try and we have seen one in a photo from uhoh off a sun glint, but overall I'm not hearing people complain. Others might want to comment on this point if they have had issues....Show more →
Thanks so much for summarizing, too! Warranty is not an issue for me anymore since mine will expire anyway this month. I am mostly worried that I gain by the modification with the use of my few rangefinder lenses, but I might give up on something when using my DSLR lenses. So far I had no issues regarding sensor reflections with original A7R. I will follow this thread - I will be especially interested how DSLR lenses perform with modified sensors and also tilt/shift lenses.
p.28 #3 · A thinner sensor stack may be possible after all!
retrofocus wrote:
....
(4) Could be a dealbreaker for me - I am using all kind of glass on my A7R other than just rangefinder lenses. So far I managed well in post processing to correct for vignetting and purple color casts with my wide angle rangefinder lenses.
By all kind, do you mean a lot of native FE lenses? This is only an issue that might be noticeable on native FE. We don't know for sure the extent of this yet, but so far it seems unnoticeable (e.g. Roger's test). Also, Kolari mod would not improve (or very slightly) vignette and color cast.
p.28 #4 · A thinner sensor stack may be possible after all!
hiepphotog wrote:
By all kind, do you mean a lot of native FE lenses? This is only an issue that might be noticeable on native FE. We don't know for sure the extent of this yet, but so far it seems unnoticeable (e.g. Roger's test). Also, Kolari mod would not improve (or very slightly) vignette and color cast.
I don't even own a single FE lens! I refer to Canon DSLR lenses.
p.28 #5 · A thinner sensor stack may be possible after all!
retrofocus wrote:
Thanks so much for summarizing, too! Warranty is not an issue for me anymore since mine will expire anyway this month. I am mostly worried that I gain by the modification with the use of my few rangefinder lenses, but I might give up on something when using my DSLR lenses. So far I had no issues regarding sensor reflections with original A7R. I will follow this thread - I will be especially interested how DSLR lenses perform with modified sensors and also tilt/shift lenses.
I'm expecting to shoot this weekend and will likely use the Canon 35mm 2.8 TS and Hartblei/Zeiss 80mm Superrotator lenses, but I will not have any 'before and after' comparisons since the converted A7 is my only Sony body. I honestly don't expect much change with either of those lenses since I typically shoot them stopped down and they both have long exit pupil distances. But I will share results if I get anything I feel is worthy...
p.28 #6 · A thinner sensor stack may be possible after all!
hiepphotog wrote:
Also, Kolari mod would not improve (or very slightly) vignette and color cast.
Nicoimages on page 25 here shows a very good improvement with the CV 12/5.6 lens which vignettes severely on my A7R and has also severe purple cast in the corners. This made me mostly interested in a modification!
p.28 #7 · A thinner sensor stack may be possible after all!
retrofocus wrote:
I don't even own a single FE lens! I refer to Canon DSLR lenses.
Canon filter stacks have varied all over the place over the years (from under 1mm to around 2.5mm, see the database at LensRentals) so it's hard to know what stack Canon optimizes their DSLR lenses for. In any case, DSLR lenses generally have long exit pupil distances to clear the mirror box, so they are less affected by the modification in any case.
I don't think I have seen compelling evidence of either improvements or degradation with SLR lenses from anyone at this point. I think there have been a few examples with Canon nFD wides, but no definitive before and after samples that I remember.
We have a bunch of Leica R glass shooters here who might be able to offer better info.
p.28 #8 · A thinner sensor stack may be possible after all!
retrofocus wrote:
Nicoimages on page 25 here shows a very good improvement with the CV 12/5.6 lens which vignettes severely on my A7R and has also severe purple cast in the corners. This made me mostly interested in a modification!
Just to be 100% I clear as I don't want to mislead; all my images are corrected with the flatfield plugin in lightroom which is almost a one click operation and very easy to apply. The modification from Kolarivision will address the smeared corners problem very considerably but the colour casts and shading will still have to be corrected.
p.28 #10 · A thinner sensor stack may be possible after all!
nicoimages wrote:
Just to be 100% I clear as I don't want to mislead; all my images are corrected with the flatfield plugin in lightroom which is almost a one click operation and very easy to apply. The modification from Kolarivision will address the smeared corners problem very considerably but the colour casts and shading will still have to be corrected.
Thanks for the clarification - I saw the photos on your flickr site and assumed those are the original uncorrected files. I am using a similar workflow to correct for vignetting and color cast with this lens. The original RAW looks really bad out of the camera but after post processing those images turn out always fantastic!
When you say flatfield plugin - do you mean the LR lens profile?
p.28 #11 · A thinner sensor stack may be possible after all!
retrofocus wrote:
Thanks for the clarification - I saw the photos on your flickr site and assumed those are the original uncorrected files. I am using a similar workflow to correct for vignetting and color cast with this lens. The original RAW looks really bad out of the camera but after post processing those images turn out always fantastic!
When you say flatfield plugin - do you mean the LR lens profile?
p.28 #12 · A thinner sensor stack may be possible after all!
Yes that is the link - download the "Adobe DNG Flat Field plug-in"
Very easy to use as long as you
1. Set your RAW images to "Copy as DNG" when importing into lightroom - that way you can start working on them with the plugin immediately without having to convert manually first
2. Make sure that you capture a "correction" image with your lens set to infinity - you should ideally capture an image at each aperture but I tend to take just two - one wide open and then another at f8 which seems to work well for most correction purposes. I use piece of white opaque perspex diffuser in front of the lens and then aim the lens with the perspex towards the sky and have found that this gives the best results.
3. Import the correction image into Lightroom and then save the converted image into a separate folder.
4. Select the image you want to correct and then click file/plugin extras and select apply external correction and browse to the folder where you have saved the "correction" image to.
5. I usually correct both colour and shading but sometimes correcting for colour only works well too.
You will only have to create your "correction" images once for each lens. Once you have your lens correction profiles setup and you "copy to DNG" all your raw files on import only steps 4 and 5 have to be executed.
p.28 #13 · A thinner sensor stack may be possible after all!
Thanks, LightShow and nicoimages for your very useful help! I was unaware of this plug-in - now I have 3 methods to correct those RAW/DNG files in post-processing (LR directly, LR with this plug-in, and CornerFix). I just installed this plug-in, and it works exactly as described above. I still need to get a better reference shot - I will follow the advice and take a photo with a white diffuser against the sky.
p.28 #14 · A thinner sensor stack may be possible after all!
FYI, I bought a piece of this white acrylic from Amazon. I cut it down to a reasonable size, and shoot all of my reference frames with it. It works great!
p.28 #15 · A thinner sensor stack may be possible after all!
Nico, great shots and information!
With respect to the dust on the sensor, I am using the same technique as I did with M9. I just turn the A7rM upside down, and use a hand blower. This eradicates about 99% of any dust spots without having to resort to wet cleaning the sensor. Generally I leave the on-sensor cleaning to a Camera specialist shop, with the microscope for a minimal cost and only takes 30 mins.
p.28 #17 · A thinner sensor stack may be possible after all!
hiepphotog wrote:
Ron: thank you for your inputs. I looked at your test before but was mainly interested in how the A7 series behaved back in the day. Just looking at these two behavior on the native platform, I don't have much reservation then. I wouldn't worry too much about the infinity stop since I plan to get for each of these their own hawk's adapter for infinity adjustment.
Is it possible if you can take a quick WO shot tonight of the sky to evaluate the coma performance? I know it's full moon and all so might not be all that conclusive. Thank you.
Charles: Thank you for taking time doing that shot. Would you mind sending me the full-res version of it so I can scrutinize its performance on the modded A7R?
p.28 #19 · A thinner sensor stack may be possible after all!
uhoh7 wrote:
those are very nice Charles. I'm not a 50 lux expert, but they seem pretty darn good.
You have alot of superb shots on that site. Seriously.
Charlie, thank you for the kind words
Mar 06, 2015 at 04:08 AM
Steve Spencer Offline • • • • • • • Upload & Sell: On
p.28 #20 · A thinner sensor stack may be possible after all!
retrofocus wrote:
I don't even own a single FE lens! I refer to Canon DSLR lenses.
I would be very surprised if Canon DSLR lenses have any problem on the modified camera. They have long exit pupils so should work well and your TSE have slow max apertures as well. It would be good to test this out, but I think you should be fine. The difficulty will like be with wide angle FE lenses with short exit pupils. The two current lenses most likely to cause issues are the Loxia 35 f/2 and the just announced FE 28 f/2, and maybe the FE 35 f/2.8 but its slow max aperture might help.
