Background: EOS 7D with EF24-105 L F4, F4 EF70-200 L, EF-S 10-22, EF 50 F1.4
Criteria: I was looking for a fast standard zoom for reportage and landscape photography
Test Candidates: EF 24-70 L F2.8, EF-S 17-55 F2.8, F2.8 Sigma 17-50
After the first test, the 24-70L was eliminated because it is useful in crop factor 1.6 for landscapes only conditionally as a universal zoom and could not quite keep up with the other two test candidates also of the resolution. In point resolution and sharpness was my 24-105 clearly superior.
The EF-S 17-55 and the Sigma 17-50 really gave me the test and the selection very difficult. Both lenses have an excellent resolution and sharpness, with the Canon in the corners of a track was subjectively sharper. In contrast, the Sigma had less vignetting and better contrast distribution on the image. At Canon, the contrast but fell towards the edge visible.
Both lenses were properly adjusted and no baking / front focus detected (tested with Traumflieger chart).
To let there be no misunderstanding here, both lenses showed in the test at the highest level and comparable to my L lenses. The differences were really minimal and the choice in favor of the sigmoid colon more subjective than objective really justifiable.
The workmanship is very good in both lenses, a tick felt better at Sigma.
Decision:
The decision for this Sigma I felled due to better and more consistent for me contrast that was particularly evident in comparison shots in the countryside. One reason against the Canon was also in many forums to read, probably more frequently occurring problem with dust in the lens. I could not notice the test, but was in, as I said more subjective, decision then but a reason more to take the Sigma.
Initial experience:
After two photo essays and about 1000 photos I have not regretted the decision and am thrilled totally by the Sigma optics. Very high resolution and sharpness even with maximum aperture and no visible diffraction effects to aperture 16 this lens have made my absolute standard lens and "always on it" look. I highly recommend this lens fully and would buy it again at any time.
This is my first review and I hope I was able to meet the demands of discerning readers. After I had even done me so hard in the choice, I thought it would be helpful to make my experience available here.
I wish everyone a lot of fun and joy with this lens.