Comparison of two Sigma AF 12-24 mm f:4.5-5.6 EX DG zooms on a Canon EOS 10D
Upon acquiring the Sigma AF 12-24 I went out to my normal test site, the Botanical Gardens of Copenhagen. When I latter saw the images on my computer screen my first impression was immense disappointment. I knew this lens due to its extreme construction could be a little soft at the edges, but I hadn't expected anything like that.
So, I took it to my camera dealer (Kamerahuset in Copenhagen) and they sent it to the distributor (Fovitech) for repair. However, when I returned to pick up the fixed lens it turned out that Fovitech had replaced it. Now I went back to the test site and shot a series of images with the new lens. This one actually performs better than I had originally expected.
Both lenses were tested at different focal length and at different f-stops using a Canon EOS 10D set at ISO 100. Unfortunately the lighting differs greatly between the two test sessions, but having returned the first lens, there was no other way to do the comparison.
The photographed scene:
The Greenhouse in Copenhagen Botanical Gardens
Shot with first copy @ 12 mm and f. 11
Shot with second copy @ 12 mm and f. 11
The camera was tripod mounted. Images were captured as RAW and converted to 24 bit TIFF files using DPP 126.96.36.199. Sharpness was set to 0 (no sharpening) and no other postprocessing has been applied to the images. 200x200 pixel crops were excised from the centre and periphery and saved as TIFF prior to conversion as JPEG files.