Phillip Reeve wrote: zmix wrote: Phillip Reeve wrote: zmix wrote:
I\'ve been following this thread with some dismay.
I had hoped that the Alpha 7 or 7r might be a suitable FF replacement for my current APS format Ricoh GXR A12 (Leica M mount) camera. Unlike the NEX (and apparently the Alpha 7) the Ricoh does not suffer from chromatic aberrations, loss of peripheral sharpness or the visible distortion in Phillip Reeve\'s initial test shots at the beginning of this thread.
Thats becaus it is a aps-c sensor. My lenses have much better corners on a Nex-6 as well.
It\'s not the format, it\'s the camera:
The Nex has horrible corners and noticeable loss of sharpness compared to the Ricoh.
Phillip Reeve wrote:
zmix wrote:
\"Magenta Hue\"
This is most certainly due to spherical chromaticism or axial chromatic aberration.
I think you got many things wrong. Colorshift or Magenta Hue as you call it is not related to CA, my Zeiss Biogn 28 for example shows really litte CA but some Colorshift. The Minolta MD 2.8/28 has a lot more CA but no Colorshift.
I don\'t think I got \"many things wrong\" Phillip. ...
\"There are two types of chromatic aberration: axial (longitudinal), and transverse (lateral). Axial aberration occurs when different wavelengths of light are focused at different distances from the lens, i.e., different points on the optical axis (focus shift). Transverse aberration occurs when different wavelengths are focused at different positions in the focal plane (because the magnification and/or distortion of the lens also varies with wavelength; indicated in graphs as (change in) focus length). The acronym LCA is used, but ambiguous, and may refer to either longitudinal or lateral CA; for clarity, this article uses \"axial\" (shift in the direction of the optical axis) and \"transverse\" (shift perpendicular to the optical axis, in the plane of the sensor or film).\"
Now you are mixing two problems:
1) Cornersmearing which only happens with symmetrical wide angel lenses like the CV15 or G28. The Sony A7 performs rather bad here, true.
2) Unsharp corners in general. The A7 will produce as sharp corners as a Nikon D600 or Canon 5d 2/3 with the same lenses.
Regarding CA: You did not respond to my argument.
I guess I didn\'t realize that you had stated an argument, but I would like to address it, perhaps you could clarify your point of view beyond stating that you thought I had gotten \"many things wrong\".
In my initial response, I was actually pointing out several separate issues with the Alpha and Nex series cameras and attributing them to their specific causes, not \"mixing two problems\", as you contend, Phillip
Allow me to address two of my points separately:
Problem 1
Distortion and blurring in the corners.
This is a serious problem on both the Alpha 7 and the NEX series cameras. Ricoh designed a layer of micro lenses to correct this on the A12 (M-mount) module. They have different modules (which include sensors) for their own lenses. It\'s been a great service to the Leica user. It is unlikely that Sony will address this issue, for the reason stated earlier in this thread: they are interested in selling new lenses.
Problem 2: Magenta Hue, (as one poster here named it regarding his Summilux) is the result of spherical chromaticism. This is a function of the lens, and as I showed in my examples, can even be reproduced by the Leica - optimized Ricoh GXR. As I demonstrated by my tests, it occurs across the entire field, not just at the edges as you would find with the more common \"CA\"
I\'m certain I wold be very upset and disappointed if I had bought the Alpha 7 and discovered the issues you have bravely revealed here, Phillip. This thread has been a great resource of possible solutions and other issues (as well as a wealth of misinformation and speculation, but hey - it\'s the internet!). Let\'s hope it continues in a collaborative vein.
Nov 22, 2013 at 04:19 PM
Previous versions of zmix's message #11953081 « Sony A7 - first impressions and some tests »
