I bought the Sony a6000 bundle (with extra batteries, 64GB SD card, the 16-50mm f/3.5-5.6 kit lens, and other fairly useless stuff).
I borrowed a Zeiss 55mm f/1.8 sweetie lens from a chum who owns an A7r. The other two lenses are the kit lens and a lens I bought in 1972 for my Canon film camera, the 50mm FD f/1.4. I use a Metabones Speed Booster to couple the FD lens to the E-mount, which turns it into a 35.7mm f/1.0 lens.
Here are the three pix. All are shot at f/5.6, ISO 100, 1/6 sec on a tripod in my office. I used the self timer to actually release the shutter. Post-processing on the JPEG was to remove all color (saturation = 0) and to increase the contrast by 30%.
Canon FD 50mm f/1.4 + Speed Booster
Sony 16-50mm f/3.5-5.6
Zeiss 55mm f/1.8
These look surprisingly similar! I didn't get the distance right on the Zeiss, so the 100% crop shows the pattern a little bit bigger.
Here is the uncropped and unedited image from the Canon (the others, at this resolution are almost indistinguishable).
I think you can see that the overall quality of the Zeiss in this specific situation is (only) a little bit better than the other two. I am not sure if I can tell the difference between the old FD 50mm and the Sony kit lens, though. The numerals on the Canon FD look a bit sharper, but the lines on the Sony look a bit more distinct.
The Sony a6000 is applying lens corrections (I think) to the two electronic lenses but not the Canon. The biggest impact of this adjustment may be that this full image from the Canon, above, has a bit of dark vignetting (whereas the others do not).
Acknowledged problems with this measurement:
- Terrible fluorescent lighting in my office.
- Inconsistent framing of the target on these three shots
- I was not far enough away for the numbers on the chart to be meaningful.
I may publish shots from the Canon at f/1.0 and from the Zeiss at f/1.8, just for fun.
- The Sony Kit lens is absolutely appropriate for everyday use!
- The old Canon is a fine (and maybe great) lens.
Here are 100% crops for the Canon at f/1.0 (equivalent) and the Zeiss at f/1.8 (I moved the tripod closer to the image for the Canon shot in order to make the target about the same size in the frame.)
Canon FD f/1.4 at f/1.0 (equivalent)
Zeiss 55mm f/1.8 at f/1.8