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| p.3 #4 · p.3 #4 · Review: Sony A7R teams up with Canon glass |
The 36MP sensor of the camera brings out the best and worst of your lenses. Lenses that perform somewhat weak in the corners tend to stand out more now since its weakness becomes now magnified. But if you stop down the aperture 3-4 stops you will notice a significant improvement there.
IMHO, the issues that you are referring to have mostly to do with quality of the adapter. And people tend to pixel peep now since it is a new camera and notice more "issues" they didn't notice before since the camera they used before did not quite have the...Show more →
Thanks for those additional comments to complement a great review and pictures.
I wonder how much is adapter "tilt" and how much just poor edge performance being better "seen" by the higher density sensor. DPR's quantitative data shows for several (3rd party) lenses a significant improvement (almost as much as you would predict, but not quite) in the centre but little improvement at the edges when compared on 5D2 and D800. (The Sigma 35 is one). I think I recall Fred saying earlier that some of his problems could be solved by tilting the lens (only on TS obviously) but field...Show more →
There are too many moving parts , let's call them using their fancy names, too many variables . It was time consuming and frankly, quite confusing. In the beginning, I wasn't even aware that adapter tilting would cause that and I wrote if off as a bad corner performance of a lens. Then I tried the same lens using another adapter, hey, I got different result and it seemed like the lens was not bad at all. The direction of tilting of the adapter is not always consistent either, although two of the same brand (mine and that of a shooting buddy of mine) were both tilted in the same direction.
The field curvature of the lens definitely plays a role. BTW, Sony's sensor has built-in micro prisms that are off-set towards the corners. So, depending on the degree of field curvature of a particular lens, it may work out just fine and it can take advantage of that feature. That's the way Leica did it plus that is supported by a powerful lens-specific software correction via the 6-bit code. BTW, I found out yesterday on the Sony application site that there is a new app (for a paltry sum of $4.99) that lets you put in lens correction data for specific lenses. Frankly, I have not bought it. I am not even sure whether it is only for Sony lenses. Since some adapters enable the camera to identify selected Canon lenses, it is possible that it may work on those, too. It seems that the type and amount of correction is more for color shifting and not for smearing. Plus, it maybe only for JPG images. In that case.... meh . I just downloaded the remote control app for my phone/iPad yesterday. But I will look into that later.
To answer your question, no, I didn't do any focus adjustment or tilting targeting the corners. I am not sure whether Fred did it or not. Frankly, it would be better to just get a perfectly aligned adapter (yes, that goes without saying, right?) and you go from there. Yes, you stop down the lens to get the desired DOF/corner performance, especially if you do some kind of tilting/shifting. BTW, I noticed that RF adapters are less susceptible to this issue because of the shorter distance to the sensor.
Hope this helps,