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Archive 2013 · Sony A7 and A7r Full Frame with Canon Lenses
  
 
snapsy
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p.93 #1 · p.93 #1 · Sony A7 and A7r Full Frame with Canon Lenses


artd wrote:
I think what we're going to find is the corner issue is going to be a little more nuanced. I just read an interesting article Roger Cicala wrote about where we was testing some adapted lenses to an A7r. ( http://www.lensrentals.com/blog/2013/12/sony-a7r-a-rising-tide-lifts-all-the-boats ) All the ones he tried showed better MTF numbers in the center than the native mount. And with the corners, the MTF numbers did show a drop, but the MTF numbers were not worse than what they were on the native mount. Now, I don't believe he tested anything wider than 35mmm yet, and it's quite possible that
...Show more

I agree, time will tell how this shakes out. Also agree that lenses longer than 35mm will likely show the issue less. But at 35mm and below the disparity seems rather stark. If you look at the 32mm f/2 IS numbers, the center MTF is 2x higher than the corners on the A7R vs 1.5x on the 5DM2. So while the corner resolution on the A7R doesn't drop below the 5DM2's I think the disparity between the two is rather striking and has to be obvious in a HQ print.



Dec 17, 2013 at 06:58 PM
RobDickinson
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p.93 #2 · p.93 #2 · Sony A7 and A7r Full Frame with Canon Lenses


Fred as an experiment how is the lhs when using a tse shifted left?

Ie is it the converter causing corner softness or have we just hit the resolving power of these lenses in the corners but not the center, as we get at least as good results as native mounts



Dec 17, 2013 at 09:35 PM
Fred Miranda
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p.93 #3 · p.93 #3 · Sony A7 and A7r Full Frame with Canon Lenses


RobDickinson wrote:
Fred as an experiment how is the lhs when using a tse shifted left?

Ie is it the converter causing corner softness or have we just hit the resolving power of these lenses in the corners but not the center, as we get at least as good results as native mounts


The first 3 links from this post show 100% crops from the upper left corner of an extreme left shift. (-12mm)

I am considering 3 possible culprits:

1) Adapter misalignment
2) A7R mount misalignment
3) A7R shorter flange-to-sensor and microlenses design.

There is nothing we can do if the problem is 3).
Just to make sure, I ordered 2 new metabones and another Sony A7R. As soon as I get them, I will test new combinations and post an update.



Dec 17, 2013 at 10:18 PM
Roland W
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p.93 #4 · p.93 #4 · Sony A7 and A7r Full Frame with Canon Lenses


For analysis of the cause of Canon TS-E lenses being soft in one corner or along one edge when used on the A7r, there are a few thing that might be tried to help determine the cause.

One possible cause that Fred left out is that the particular TS-E lens you are trying does not lock accuratly at zero tilt. Besides knowing that the lens works well on a Canon full frame camera, you could also do a check on the A7r by rotating the tilt part of the lens 180 degrees and also changing the shift to the other side, and see if the soft location moves to opposite after the rotation, or stays in the same place on the A7r. If it moves, the lens may not be accurate for its zero tilt lock. If the soft location stays in the same place on the image, then there is some tilt coming in at the adapter or in the camera.

For the issue mentioned above by Fred in number 3, that relates to the microlens design of the camera sensor working with high angles of incidence, there is a check that should show if that is the problem. If you see the issue with a maximum shift to one side, try reversing the shift to maximum the other way, and see if the problem moves to the other side. If it moves, then the microlenses may not be capable of accepting the higher angle of incidence that light from a shifted lens has. I know that Canon put in a lot of work a while back to get the corners of their full frame sensors to work fairly well with wide angle lenses, and perhaps Sony just did not allow for really wide lenses. But it also seems like Sony would know better, and they also need to make their own wide lenses work well. And actually Sony lenses with the shorter back focus will likely have even sharper angles of incidence than an adapted Canon lens of the same focal length. What is the widest native Sony lens for the A7r, and are there reports of how well it works in the corners?

I hope you guys get this all figured out, so I know if I should consider an A7r, or should just wait and save up a bunch of money to buy what ever Canon comes up with for high resolution.



Dec 17, 2013 at 11:02 PM
artd
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p.93 #5 · p.93 #5 · Sony A7 and A7r Full Frame with Canon Lenses


snapsy wrote:
I agree, time will tell how this shakes out. Also agree that lenses longer than 35mm will likely show the issue less. But at 35mm and below the disparity seems rather stark. If you look at the 32mm f/2 IS numbers, the center MTF is 2x higher than the corners on the A7R vs 1.5x on the 5DM2. So while the corner resolution on the A7R doesn't drop below the 5DM2's I think the disparity between the two is rather striking and has to be obvious in a HQ print.

The disparity may be striking numerically, but that doesn't automatically translate to being obvious in a real world scenario. You can't really know from the numbers, you'll only ever know from an actual print.

And of course, topics of when something does or doesn't noticeably affect a print are hotly debated on these forums.



Dec 18, 2013 at 01:59 AM
Luta13
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p.93 #6 · p.93 #6 · Sony A7 and A7r Full Frame with Canon Lenses


secondclaw wrote:
Hah I was about to post the same. On my 5d2, when I boost shadows in high iso situation, I want to throw up. First time I pushed shadows on nex-7 it was a revelation.


NEX-7 files cant hold a candle to a modern Canon FF (6D/ 5DIII) as far as work-ability in post. Not even close and I own both the Sony and the Canon. Besides, what high ISO are you shooting on the NEX-7? Grain is noticeable at about ISO 800 and detail smudging gets nasty about ISO 1600 (I only know this from use of mine and NOT a lab of any sort). By comparison, a 6D is still putting out very nice files in those ranges.
You are comparing the Sony camera to a Canon camera that is +3 years behind in technological advancement.
That said, the Sony NEX7 is a great little camera and I hope the newer Sony's are a continued improvement. I love the NEX7 for what it is.



Dec 18, 2013 at 04:32 AM
efgm
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p.93 #7 · p.93 #7 · Sony A7 and A7r Full Frame with Canon Lenses







Free Image Hosting by imgbox.com

Here's some mechanical vignetting tests with the Metabones adapter III. Bit of a mixed bag really.



Dec 18, 2013 at 08:20 AM
KiboOst
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p.93 #8 · p.93 #8 · Sony A7 and A7r Full Frame with Canon Lenses


Is such shape of the bokeh in corners usual ? Couldn't be the design of microlenses in corners ?


Dec 18, 2013 at 10:11 AM
Matt Grum
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p.93 #9 · p.93 #9 · Sony A7 and A7r Full Frame with Canon Lenses


KiboOst wrote:
Is such shape of the bokeh in corners usual ? Couldn't be the design of microlenses in corners ?


It's nothing to do with microlenses.

The oval shape toward the corners is vignetting induced by the front of the lens barrel, and ought to be independent of the camera used, and is quite normal for very large aperture lenses.

The cropping effect is due to obstructions behind the lens, i.e. the mirror box, or in the case of the A7, the adapter itself.



Dec 18, 2013 at 11:57 AM
Lars Johnsson
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p.93 #10 · p.93 #10 · Sony A7 and A7r Full Frame with Canon Lenses


The oval shape is normal on that lens (85/1,2). And not only in the corners. Here is a shot from mine with the Canon 1DX. So you can see it has very little or nothing to do with the A7R or the adapter.
http://www.pbase.com/larsjohnsson/image/151858319/original.jpg



Dec 18, 2013 at 12:18 PM
 

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Fred Miranda
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p.93 #11 · p.93 #11 · Sony A7 and A7r Full Frame with Canon Lenses


Roland W wrote:
For analysis of the cause of Canon TS-E lenses being soft in one corner or along one edge when used on the A7r, there are a few thing that might be tried to help determine the cause.

One possible cause that Fred left out is that the particular TS-E lens you are trying does not lock accuratly at zero tilt. Besides knowing that the lens works well on a Canon full frame camera, you could also do a check on the A7r by rotating the tilt part of the lens 180 degrees and also changing the shift to the
...Show more

Great ideas for testing the TS-E 17mm Roland. I think the lens is not at fault. It is not decentered and have accurate tilt-lock. The same issue happens with other wide angles like the Sammy 14mm, Canon 24-70 II @24mm and TS-E 24mm.

There is smearing/low contrast in all the extreme corners but specially on the upper ones. When moving towards the center, the resolution is impressive though. I really think I have a bunch of slightly decentered adapters or camera mount. I will find out tomorrow for sure.
I'm starting to think that even with a perfect centered adapter, the extreme corners will not follow the amazing resolution gain I see in the center and this is probably due to the thickness of the glass in front of the Sony sensor.
Fred



Dec 18, 2013 at 11:42 PM
RobDickinson
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p.93 #12 · p.93 #12 · Sony A7 and A7r Full Frame with Canon Lenses


Have seen a report on LL forums about the metabones adapter reflecting light when using shift and causing contrast issues, they used some black velour and sorted it out


Dec 18, 2013 at 11:55 PM
Pixel Perfect
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p.93 #13 · p.93 #13 · Sony A7 and A7r Full Frame with Canon Lenses


Lars Johnsson wrote:
The oval shape is normal on that lens (85/1,2). And not only in the corners. Here is a shot from mine with the Canon 1DX.


The oval shape of the OOF highlights has zero to do with the camera other than format size, and is due to vignetting by the extreme wide angle rays you get at such large apertures within the lens. To these rays, the aperture they see is is effectively elliptical, formed by the intersection of two circles. To see this for yourself, take a tube and look at it straight on and then slowly change the viewing angle to the side and you'll see the aperture go from circular to elliptical. As you can see the OOF highlights are indeed near circular away from the periphery of the sensor.



Dec 19, 2013 at 02:30 AM
galenapass
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p.93 #14 · p.93 #14 · Sony A7 and A7r Full Frame with Canon Lenses


Luta13 wrote:
NEX-7 files cant hold a candle to a modern Canon FF (6D/ 5DIII) as far as work-ability in post. Not even close and I own both the Sony and the Canon. Besides, what high ISO are you shooting on the NEX-7? Grain is noticeable at about ISO 800 and detail smudging gets nasty about ISO 1600 (I only know this from use of mine and NOT a lab of any sort). By comparison, a 6D is still putting out very nice files in those ranges.
You are comparing the Sony camera to a Canon camera that is +3 years behind in
...Show more

Imagine if he would have compared a full frame Sony sensor to a 5DIII. Oh wait, I guess I don't have to imagine...

http://www.fredmiranda.com/5DIII-D800/index.html





Dec 19, 2013 at 03:24 AM
beetlephoto
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p.93 #15 · p.93 #15 · Sony A7 and A7r Full Frame with Canon Lenses


Fred Miranda wrote:
Great ideas for testing the TS-E 17mm Roland. I think the lens is not at fault. It is not decentered and have accurate tilt-lock. The same issue happens with other wide angles like the Sammy 14mm, Canon 24-70 II @24mm and TS-E 24mm.

There is smearing/low contrast in all the extreme corners but specially on the upper ones. When moving towards the center, the resolution is impressive though. I really think I have a bunch of slightly decentered adapters or camera mount. I will find out tomorrow for sure.
I'm starting to think that even with a perfect centered adapter,
...Show more
I'm using a Canon TS-E 17mm with success on my A7r, although I have seen in this thread that the borders are not up to what they could be on a Canon DSLR. My experience is limited so far with this combo but somehow I sometimes get softer corners than what I would expect, and sometimes über sharp corners (non focus/DOF related). I'm thinking it might have to do with me locking the lens (or not) before taking the picture, even the smallest amount of movement (non locked vs. locked) could potentially affect corner sharpness. I'll run a batch of tests to verify this shortly. But what puzzles me is that the softer corners seem to be on the right side of the frame mostly, so this seems to suggest that either:
-The lens elements are not perfectly aligned
-The Metabones MKIII adapter is not perfectly straight
-The A7r mount is not straight (don't believe that is the case as I have no issues with a Noctilux f/1 with a Novoflex adapter)
-As mentioned above, the locking knob has an influence on the plane of focus

Just trying to list all the potential causes for this. A good idea has come up above, I will try to test the lens with 90° rotation to see if the bottom right corner is still soft. If yes, then it is a misalignment from the mount/adapter/lens flange. If not, then it comes from the lens itself.



Dec 19, 2013 at 08:59 AM
beetlephoto
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p.93 #16 · p.93 #16 · Sony A7 and A7r Full Frame with Canon Lenses


RobDickinson wrote:
Have seen a report on LL forums about the metabones adapter reflecting light when using shift and causing contrast issues, they used some black velour and sorted it out

Would you have a link to this thread, please?

Edit - Found it : http://www.luminous-landscape.com/forum/index.php?topic=8524

But to me it looks like it is more a contrast issue that is being solved here, rather than the smearing. I will give it a shot, just to see if that helps.



Dec 19, 2013 at 09:07 AM
marc aurel
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p.93 #17 · p.93 #17 · Sony A7 and A7r Full Frame with Canon Lenses


A7R+TS-E 24: Internal reflections in Metabones III adapter and what could help


I post it here to share it with the ones who are not registered on LL. So:

I made a comparison with TS-E24 II on A7R and 5DIII, using shift. In the centre of the unshifted lens, the A7R has more resolution. Most obvious in the meander of the tympanon and the grid in the window. In the extreme corners of the shifted image resolution of both cameras is very close.
But additionally there is a degradgation of contrast in the shifted area in the A7R image compared to the 5DIII - the A7r image looks worse which I didn't expect - the black isn't really black. I suspected internal reflections in the adapter - something that has been reported about the TS-Es in another forum too. So I bought some self-adhesive velour to cover the interior of the metabones - Canon uses something similar for the interior of the TS-Es. I repeated the test. It was difficult to find a day with similar weather (no direkt sun), so the test is not perfect (light was a bit more contrasty on the second test).
I used tripod. Focused on extremes corner with live view. Raws converted in Lightroom 5.3. Adjusted white balance a bit to make images look similar. Sharpening for all: Amount: 50 - Radius: 0,7 - Detail: 30 - Mask: 4. Test 1 is before, Test 2 after changing the interior of the adapter. 100% crops (I tried up- und downscaling one or both to match sizes; results were similar).

In my eyes one can clearly see that in Test 1 the A7R image of the shifted area is less contrasty. In Test 2 - with the metabones with velour - it isn't. A7R still doesn't show a resolution advantage in the extreme corners - maybe the lens doesn't give enough resolution there. But it's not worse than the canon any more. And in the centre and most other parts of the image the A7R is much better.
I suspect that TS-E causes more reflections than other lenses beacuse the larger image circle hits more surfaces of the adapter interior.

I tried to visualize what happen's with that combination. Section unshifted and with full shift (see image below). With its image circle of 67mm the TS-E hits a lot of surfaces inside the metabones that can reflect. Maybe the rear element of the lens reflects back to the sensor.

marc aurel






















Dec 19, 2013 at 06:17 PM
marc aurel
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p.93 #18 · p.93 #18 · Sony A7 and A7r Full Frame with Canon Lenses



A7R+TS-E 24: Internal reflections in Metabones III adapter and what could help - Part 2: how to do it

The geometry of the adapter is not very simple, so it's a bit tricky to do. Below are images of how it looks after the modification.
I made a cutting pattern which consists of several perts (see below). It's not absolutely precise, but it worked well. The jpg with the cutting pattern is scaled 1:1, so you could use it to try. Your own risk of course... ubt the self-adhesive velour i used could be removed without problems.
At first I covered every surface inside. Then I noticed that at a shift of more than 10mm the velours interfered with the optical beam path (the opening of the adapter is just about 36x24mm). When shifted up (rise), the lowest part of the image bottom went darker. When shifting down (fall), it went darker on top.
So I took off the velour on one surface (marked green in the cutting pattern), but only the one that interfered with the shift up (cause i don't use more than 10mm of shift down). The problem was gone and it didn't visibly change the image quality. Either this was not the problematic surface, or it is sufficient to treat most of the surfaces to prevent a ping-pong-effect of reflections. Image 2 shows how that looks. You can also see that - despite of the matte black finishing - the metal does reflect.
Maybe it's not to everyones taste do such things - but now i get the best image quality available for this sensor size when shift is needed.

marc aurel

















Dec 19, 2013 at 06:23 PM
Fred Miranda
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p.93 #19 · p.93 #19 · Sony A7 and A7r Full Frame with Canon Lenses


Thanks for posting this here Marc!
I encountered the same low contrast issue with the TS-E 17mm even with the lens unshifted.
I glued your printed 1:1 diagram on the back of a black felt sheet and was able to precisely make the cutouts. It fits the adapter great.
I am waiting for a new Metabones copy to post more tests because the one I have is clearly tilted.
Fred







Dec 19, 2013 at 06:33 PM
AGeoJO
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p.93 #20 · p.93 #20 · Sony A7 and A7r Full Frame with Canon Lenses


Marc, you did really a good job putting that sticky velour on the adapter . Thank you also for the instruction on how to do it .


Dec 19, 2013 at 06:34 PM
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