If you have experiences good or bad with Sony's lens repair service please post to share your experience
I have a Zeiss ZA Vario-Sonnar T* 24-70mm f/2.8 SSM (Sony SAL-2470Z) lens that I'm thinking of sending into Sony's Repair Center in Texas for repair. I've noticed significant softness in the field (a recent trip to Big Bend NP) at 70 mm vs good sharpness at 24-50 mm. My Imatest test results validate what I see in the field. Some Imatest results:
Zeiss 24-70mm f/2.8 SSM
* 24 mm, f5.6
- 9 non-corner locations average = 2228 lw/ph
- 9 points + 4 corner points average = 2024 lw/ph
* 50 mm, f5.6
- 9 non-corner locations average = 2151 lw/ph
- 9 points + 4 corner points average = 1994 lw/ph
* 70 mm, f5.6
- 9 non-corner locations average = 1912 lw/ph
- 9 points + 4 corner points average = 1754 lw/ph
The center point at 70 mm is very sharp (2380 lw/ph at 70mm, vs 2300 lw/ph for 50 mm and 2370 lw/ph at 24 mm) but sharpness degrades very fast as the location moves away from center at 70mm. The magnitude of this behavior is not seen at 50 mm and 24mm.
F8 Data (I shoot at landscapes and therefore 'live' at f5.6-11):
Zeiss 24-70mm f/2.8 SSM
* 24 mm, f8
- 9 non-corner locations average = 2123 lw/ph
- 9 points + 4 corner points average = 2014 lw/ph
* 50 mm, f8
- 9 non-corner locations average = 2119 lw/ph
- 9 points + 4 corner points average = 2026 lw/ph
* 70 mm, f8
- 9 non-corner locations average = 1978 lw/ph
- 9 points + 4 corner points average = 1835 lw/ph
Notice that moving from f5.6 to f8 results in decreases in sharpness at 24 and 50 mm, but an increase in sharpness at 70 mm.
Most tests that I've seen online show equivalent performance at 24, 50 (or 40mm) and 70 mm for the Zeiss 24-70 f2.8. The one exception, which matches my experience, is the DIWA lab results at
http://www.diwa-labs.com/wip4/compare_lens.epl?id=274121 which shows corner sharpness at 70 mm to be much lower than center sharpness, which is what I am seeing.
For those who are curious on how the Zeiss compares to my Canon lenses:
* Canon 24 mm f1.4 I: at f5.6
- 9 non-corner locations average = 2292 lw/ph
- 9 points + 4 corner points average = 2232 lw/ph
* Canon 24 mm f1.4 I: at f8
- 9 non-corner locations average = 2206 lw/ph
- 9 points + 4 corner points average = 2156 lw/ph
* Canon 24-105 mm f4 I: at f5.6 and 50mm (which I had to have repaired by Canon for softness)
- 9 non-corner locations average = 1867 lw/ph
- 9 points + 4 corner points average = 1812 lw/ph
* Canon 24-105 mm f4 I: at f8 and 50mm
- 9 non-corner locations average = 1937 lw/ph
- 9 points + 4 corner points average = 1868 lw/ph
* Canon 50 mm f1.4 I: at f5.6
- 9 non-corner locations average = 2349 lw/ph
- 9 points + 4 corner points average = 2318 lw/ph
* Canon 50 mm f1.4 I: at f8
- 9 non-corner locations average = 2246 lw/ph
- 9 points + 4 corner points average = 2246 lw/ph
The Zeiss's performance slot it in between the Canon 24-105 mm lens and the 2 Canon primes. Even with the behavior I am seeing at 70 mm, the Zeiss lens looks to be the sharpest zoom lens I've seen at any focal length.
For Imatest, I use a 60x90 inch target that consists of 3.5 in square gray blocks printed at 9600 dpi. I run through several different focuses to account for the curvature of the wall that I am using and field curvature of the lens (which is excellent in the Zeiss lens). I process the RAW files in Lightroom, using autowhite, autotone, I set Black to 0, use a linear curve, with no sharpening or noise reduction. I've found for sharpness testing on the Sony that there is no difference between Capture One and Lightroom, although, as several have posted, noise control is somewhat better in CR.
I'm trying to figure out if my Zeiss lens is typical or not. I like its performance up to about 55 mm, after that, I'm not happy with it. If my lens is not typical, then I'd like to send it in for repair to Sony's lens service center, but I've not found much online that tells me about other people's experience with Sony Repair. Any experiences that you can share would be appreciated. Thank you.