Some time ago I had this photo session for a company – some portraits made “on location” using my Quadra. Now, I had this 18-50 lens that I adore but that had a bit of a focus issue on my SD14 so I brought one of my photo students Nikon D90 to be on the safe side (same sensor as seen in the D300s). I took all shots with both cameras. The Nikon had the regular 18-105mm VR lens – I have no idea how that one compares to Sigmas 18-50 but the Nikon cost about the same when it hit the market (about $400).
The Nikon has been shot at F10, the Sigma at F8. Nikon with ISO200 and Sigma at ISO100. (ISO200 is standard on the D90). Also, notice that the Sigma is slightly closer. Nikon is set at 66mm and Sigma at 50mm. So the Sigma’s at maximum zoom level (which normally is a disadvantage).
You can’t click the above shot to zoom in, but the other two shots below. Notice that the Sigma has no extra sharpening applied. Just standard from SPP3. Nikon is sharpened normally in Lightroom 3.
Conclusion? Those 4.6MP’s are truly insane!