Archive 2015 · A thinner sensor stack may be possible after all!
zzp120 Offline • [X]
p.29 #1 · A thinner sensor stack may be possible after all!
Hi All,
It is great to find such improvement on the thin glass conversion. I own a hologon G16 and have been hoping to use it on digital camera for a long time, the result on a7/a7r really disappoint me. However, a7s seem like a very good option if the thin glass conversion can fix the problematic corner. Did anyone try G16 on a7sm? Or anyone live near Atlanta own an a7sM?
p.29 #2 · A thinner sensor stack may be possible after all!
You mentioned the black beast of the stable, for what concerns lens compatibility in the mirrorless/rangefinder digital world.
An extreme wideangle with a perfectly symmetrical design which, I suspect, never will be fully usable for regular photography on a digital camera, unless there's a revolutionary improvement in the way that sensors behave with acute angles of incidence.
Couldn't you settle on something a bit more friendly, like a Biogon 21 ?..
p.29 #3 · A thinner sensor stack may be possible after all!
artur5 wrote:
You mentioned the black beast of the stable, for what concerns lens compatibility in the mirrorless/rangefinder digital world.
An extreme wideangle with a perfectly symmetrical design which, I suspect, never will be fully usable for regular photography on a digital camera, unless there's a revolutionary improvement in the way that sensors behave with acute angles of incidence.
Couldn't you settle on something a bit more friendly, like a Biogon 21 ?..
Actually, the Hologon 16 is fully usable on the MM and very sharp corner-to-corner. It's one the lenses I intend to try out after I get my A7s.Mod back. Have the G 21 & 28 ready though .
Thank you Charles. That's plenty sharp for me. It's definitely a challenged to maximize the sharpness across the frame on this one. The DOF of the 50 is just not enough.
p.29 #5 · A thinner sensor stack may be possible after all!
hiepphotog wrote:
Thank you Charles. That's plenty sharp for me. It's definitely a challenged to maximize the sharpness across the frame on this one. The DOF of the 50 is just not enough.
I agree, with the 50 Lux Asph the DOF is substantially reduced when you set the focus at infinity, rather than using the hyper focal range. But for sharpness and pixel peeping at 36MP the hyper focal range is a compromise now. I chose this scene as it would illustrate the fall off in focus.
p.29 #6 · A thinner sensor stack may be possible after all!
hiepphotog wrote:
Actually, the Hologon 16 is fully usable on the MM and very sharp corner-to-corner. It's one the lenses I intend to try out after I get my A7s.Mod back. Have the G 21 & 28 ready though .
Eagerly waiting to find out how the 21mm does!
p.29 #7 · A thinner sensor stack may be possible after all!
I have just been testing the Adobe FF corrections again with the M28v3.
Same shot as before but with FF external correction applied in Lr. I used a Capture One light card, originally meant for C1 Pro corrections. It is basically a translucent perspex card.
As Nico suggested I take the shots, at f/2.8 and f/8 both near and far and keep them in a separate file.
p.29 #8 · A thinner sensor stack may be possible after all!
artur5 wrote:
You mentioned the black beast of the stable, for what concerns lens compatibility in the mirrorless/rangefinder digital world.
An extreme wideangle with a perfectly symmetrical design which, I suspect, never will be fully usable for regular photography on a digital camera, unless there's a revolutionary improvement in the way that sensors behave with acute angles of incidence.
Couldn't you settle on something a bit more friendly, like a Biogon 21 ?..
The hologon g16 is the biggest trouble guy, however, as hiep said it works perfect at leica mm.
And it also work well on leica M9, I mean the it looks fine on the corner not on the color.
The most interesting thing is that G16 has light green color shift and very little red color shift on a7s, it is a great news!
And Kolari confirmed that a7/r/s will have same thickness stack as m9 after conversion.
As the result, I believe it will have a great chance that g16 will work fine on a7sm.
p.29 #9 · A thinner sensor stack may be possible after all!
Just out of curiosity have compared the VC21/4 between the Leica M240 and A7R Kolarivision modified taken at f11 which is the aperture that the lens is the most consistent across the frame on the Leica. The A7R files have been resized to 6000X4000 to make the comparison fair.
I have colour matched the files as closely as I could and have used the flatfield plugin to correct colour shading on both cameras - the Voigtlander 21/1.8 reference shot has not been colour corrected.
Will leave it up to you to draw your own conclusions.
p.29 #10 · A thinner sensor stack may be possible after all!
When its question of comparing the pictures taken with different cameras, it always puzzles me to no end the logic that some of you guys use. Downsizing the output of the higher Mpix. sensor to ,match the lower one is like throwing away the extra resolution of the higher camera. You could as well compare the newer 50 Mpix.Canon 5DS with a 'venerable' 4Mpix. Canon 1D downsizing those 50mp. to 4mp. and you'd conclude that the new Canon flagship has no visible advantage over a 13 year old 1D.
Do it the other way around and you'll see the real difference between a 50mp and a 4mp. sensor. The same logic applies comparing 24mp. to 36mp. sensors, etc. Always upscale the lower resolution picture to match the Mpx. count of the other. You won't throw away any info from the higher sensor and you can't add anything to the lower one, because that upscaled image will have more Mpix. but no more real resolution than the original image.
p.29 #11 · A thinner sensor stack may be possible after all!
nicoimages wrote:
Just out of curiosity have compared the VC21/4 between the Leica M240 and A7R Kolarivision modified taken at f11 which is the aperture that the lens is the most consistent across the frame on the Leica. The A7R files have been resized to 6000X4000 to make the comparison fair.
I have colour matched the files as closely as I could and will leave it up to you to draw your own conclusions.
The third file is a reference image taken with the VC21/1.8 on the Sony A7RM which is a perfect match now and a much better - but heavier - lens.
Only default Lightroom sharpening has been applied ...Show more →
That's great, thanks for sharing! At f/11 I can't see a difference between Leica and A7R_M. Only at f/5.6 I see a bit of purple color cast in the upper right corner - easy to correct in LR as discussed.
I am a big fan of this CV 21/1.8 lens!
p.29 #12 · A thinner sensor stack may be possible after all!
artur5 wrote:
When its question of comparing the pictures taken with different cameras, it always puzzles me to no end the logic that some of you guys use. Downsizing the output of the higher Mpix. sensor to ,match the lower one is like throwing away the extra resolution of the higher camera. You could as well compare the newer 50 Mpix.Canon 5DS with a 'venerable' 4Mpix. Canon 1D downsizing those 50mp. to 4mp. and you'd conclude that the new Canon flagship has no visible advantage over a 13 year old 1D.
Do it the other way around and you'll see the real difference between a 50mp and a 4mp. sensor. The same logic applies comparing 24mp. to 36mp. sensors, etc. Always upscale the lower resolution picture to match the Mpx. count of the other. You won't throw away any info from the higher sensor and you can't add anything to the lower one, because that upscaled image will have more Mpix. but no more real resolution than the original image....Show more →
The reason for downsizing the output of the A7R_M was to be able to compare the lens performance between two cameras that have different resolutions, consistently, without sensor resolution influencing the results. I don't have a modified A7 which matches the Leica M240 resolution.
This is not a "my Sony 36Mp camera is better than your Leica 24Mp camera" type comparison.
Upscaled versions of the same test can be downloaded here which proves that 24Mp upscaled to 36Mp is always going to be inferior in resolution but introduces another variable which I dont think is helpful
p.29 #13 · A thinner sensor stack may be possible after all!
To my eyes the CV21/4 on the a7R looks very fractionally more nervous/smeared at the very edges than on the M240. In real use, I doubt anyone would notice. The CV21/1.8 looks great at f/5.6!
I agree with downscaling the a7R images to match the M240's resolution. The digital Ms are the 'gold standard' for RF lenses on digital cameras. Scaling the a7R files down to 24MP gives a better apples to apples comparison of sensor smearing effects, relative to the M240. Those smearing effects would seem more exaggerated at higher resolution. Now, if the goal was to see if there is any perceptible edge smearing at all on the a7R, then viewing the full rez files would make sense.
The upscaled to a7R resolution set is interesting too... The M240 image is quite close to the a7R in the outer zone, but the a7R is somewhat better centrally. I'd guess there'd be a much more considerable difference with the 21/1.8 and that the 21/4 isn't really providing anything beyond the ~20MP range in resolution in the outer zone.
p.29 #14 · A thinner sensor stack may be possible after all!
nicoimages wrote:
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.
Today I followed your advice and took some calibration shots into the unclouded sky. As diffuser I used my matt acrylic glass which is normally used as diffuser in the stand of my stereo microscope. With the CV 12/5.6, I took two shots at f/5.6 and f/11. The difference there was not huge in the light falloff. I used the same method with my CV 21/1.8 lens - here I took shots at f/1.8, f/5.6, and f/11. There was quite a difference in the light falloff between those calibration photos.
Results with those calibration files turned out excellent with a very simple process using this LR plugin. Thanks again!
p.29 #15 · A thinner sensor stack may be possible after all!
rscheffler wrote: The M240 image is quite close to the a7R in the outer zone, but the a7R is somewhat better centrally
Leica 240 or Sony A7, cannot match 36MP sensor's resolution. This is easily visible, at full size it is, when comparing details of blinds and air con vents in the centally located bulding.
Said that, without Kolari mod the outer zone would look waaaay better on 240.
p.29 #16 · A thinner sensor stack may be possible after all!
retrofocus wrote:
With the CV 12/5.6, I took two shots at f/5.6 and f/11. The difference there was not huge in the light falloff. I used the same method with my CV 21/1.8 lens - here I took shots at f/1.8, f/5.6, and f/11. There was quite a difference in the light falloff between those calibration photos.
While the CV12mm f/5.6 isn't a biogon, its design is grounded on the same concept (in fact, without the aspherical element in back, it would probably look even more symmetrical). Designs like that have a whole lot of natural vignetting that doesn't really disappear even when stopped down. And that's on film before you account for sensor vignetting.
p.29 #17 · A thinner sensor stack may be possible after all!
TY so much for those samples Nico, very interesting and shows what a perfect copy of the CV 21/4 you have
Also a great demonstration of the Cv 21/1.8, which is really impressive at 5.6.
Basically it seems to my eye the A7r.mod is like a different camera. The wavy biazzare dips acroos the frame which I saw with all sort of lenses, including the FD 35/2 SSC, are simply gone. That was the reason I returned the camera in dec 2013.
The 36mp is moot to me as I don't crop or print so large it would ever be seen except by zooming on the image. In fact the M9 is plenty of pixels for my own uses, looking fantastic on the 5K iMac. At first I was suduced by the R's many pixels, but no longer.
It sounds like we will soon see an onslaught of huge pixel numbers from Canon and Sony, and the sighs of ecstasy will echo across all our forums.
To me that money would be better spent on finding the super thin and resilient cover glass of the future which will let our film glass burn clean and sharp as possible across the frame.
I think the M8 still holds the record in that regard
p.29 #19 · A thinner sensor stack may be possible after all!
Got out briefly to start to test some TS lenses on the A7M. Here's a test shot with the Canon FD 35mm f2.8 TS lens at f8 on the A7M. No claims of artistic merit on this one - I'll leave that to Nico.
Vertical stitch with the top of the image at full upward shift and the bottom still shifted somewhat above center (didn't note the exact position). Some swing to bring the focus line through the light on the left and the corner of the stairs about a third of the way from the right. Added to the A7M group on Flickr along with a B&W version.
The color image is uncropped so you can see the entire frame. B&W (updated on Flickr March 8) is cropped slightly on the bottom edge, but the top and sides are out to the edges of the frame.
Stitched with Microsoft ICE. Works fine for these simple stitches. Processed from RAW in Lightroom 5.x Camera Neutral profile 'As Shot' - no other adjustments on the color version.
Slight CA fringing with this lens but not bad for the vintage (mid-70's example). Nothing done to remove it in this full-res image.
I'm very happy with this performance. 100% usable and satisfying.
I know you're waiting for the 24mm and 17mm... sorry, I don't own electronic lenses as a matter of principle.
p.29 #20 · A thinner sensor stack may be possible after all!
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The field curvature in the tests below was caused by the adaptor being too short. After shimming the adaptor so that the lens did reach infinity nearer to the point indicated on the lens barrel the issue has disappeared and the lens performs perfectly now. Page 32 has the latest update and downloads of the revised test.
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Thanks for your comments everyone. Following on from Charle's Canon 35 TS test (love that building picture) have tested my Canon 24 TS-E L MkII on the Sony A7R_M
First impressions are that shifted to the extremes it is a tiny bit sharper in the corners than it used to be and behaves similarly to what I remember it on the Canon 5MkII. Had forgotten how average the lens is overall if not shifted. To demonstrate this the link below includes test pictures of all apertures with no movements applied and then two images with max shift applied at f8 and f11
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