DA* 16-50mm vs. Sigma and Tamron 17-50mm F2.8 Comparison
Image Quality: Vignetting
For this test, we placed the test camera on a tripod pointed at a blank wall. We shot each lens at f/2.8, 4.0, 5.6, and 8.0, and at 16 or 17mm, 35mm, and 50mm.
- Single-point Live View autofocus (on center of scene)
- ISO 100
- JPEG (highest quality)
- White balance set to Auto
- Auto-exposure; Multi-segment / Evaluative metering
- Image mode set to camera default ("Bright")
- Dynamic range extension off; In-camera lens corrections off
- Camera on tripod, 2-second self-timer; SR off (OS off for the Sigma)
Conclusions
At 16 or 17mm and f/2.8, the Sigma has a slight advantage over the other two lenses in terms of vignetting, but all three have significant light falloff. It maintains this advantage all the way through to f/8.0, where the Pentax and Tamron still have noticeable corner darkening. At 35mm the situation is much the same, with the Sigma leading the way and the Pentax and Tamron following, in that order. However, at this focal length vignetting is really only a problem at f/2.8—by f/4 it's essentially a non-issue. Zooming all the way in to 50mm finds the Sigma and Pentax lenses edging out the Tamron wide open. All three clean up quite well by f/4 and vignetting is essentially gone by f/5.6.
