+ Focus: In Aperture 2.8 is still very soft, starting at 3.5 but noticeably better. (Of course, my must not forget that the depth of field is very low at this aperture: that is, those photos are likely to act 'softer', although the sharpness zone fits perfectly.) At f 5 knackscharf.
+ Contrast performance above average - almost fixed focal length level!
+ Strikingly beautiful bouquet
+ Autofocus. For a 'non-ultrasonic motor "fairly quickly and quietly Accuracy I can as the owner of an EOS 450D not sure judge, because this camera also produced with L lenses sometimes incorrect measurements After some 1000 photos I would. say precision not quite on top level, but satisfactorily in a car race the 70-200 4L USM has clearly produced more clearer photos - a direct comparison is probably not quite fit .....
+ Weight: at least significantly lighter than the Canon 24-70 2.8L ... Both the 450D, as well as with the 5D is the Tamron comfortably in your hand.
+ CA: Could virtually no notice - for the price top!
+ Distortion: slight barrel distortion at 28mm, otherwise barely visible.
+ Vignette: virtually no on cameras with crop sensors - details on full frame below ....
o Processing / feel: For the price surprisingly well made. Zoom and focus ring are handy and smooth. The area of focus could be greater calm. Really precise manual focusing is difficult. The switch, which prevents using the zoom, you can without shifting hand 'flick off' with his forefinger - if you're in a hurry. I like it :)
Supplements for use with full-frame cameras:
According to Tamron lens should be fit for full-size. Did they therefore recently on a 5D Mark II tested compared to the Canon 24-70 2.8L
+ Sharpness: sharp even at full aperture format from approximately 3.5 up to the corners. The Canon 24-70 2.8L is only marginally better. Hats off - really top !!
+ CAs: minimally visible in the corners, here is the 24-70 2.8L slightly better. Cost more than 3 times. Also on VF a very good result for Tamron.
- Vignette: Have some series made with all focal lengths and different apertures. Result:
28mm: useful only about from Aperture 4,5-5.0. In Aperture 2.8 EXTREME vignetting at all corners. Proves at least that my Tamron is well centered :)
35mm-75mm: useful from about 4 aperture, but definitely worse than the Canon.
Actually Tamron should not be called a full-frame fit this lens. Or. if anything, would be the designation 'Tamron 28-75 4.5' appropriate, because under Aperture 4.5 is definitely not suitable for VF.
o Distortion: Again, is visible at 28mm distortion again, slightly more than in the crop sensor. For larger focal lengths very low distortion.
My Conclusion:
* Unbeatable on Cropkameras for the price
* Sharpness even at full frame cameras surprisingly well
* CA's scarce
* Distortion at the bottom yet - but just about acceptable for my applications.
* Vignetting on crop cameras virtually absent. In full-frame, however, with large aperture EXTREME. Who can live with it, until about 4-5 aperture to photograph is also on a VF camera with the Tamron his joy - at the price!
Supplement on 20/12/2010:
Hab now the Tamron on my EOS 3 (analog, ie full frame) also extensively tested and some photos with Aperture 2.8 made - in protest quasi :)) The results were (at least 15cm to 10 x Photos) surprisingly well. The above-mentioned vignetting is visible on any photo, am saying is in practice probably largely negligible. Who landscape is photographed with blue sky safely conclude at f 2.8 darkening in the corners. But who already makes landscape photos in broad daylight with Aperture 2.8 ???
My conclusion after 1 year with the Tamron 28-75:
- CA's minimum
- Low distortion
- Precise focus: In total I had surprisingly few incorrect measurements
- With large aperture vignetting at full-format cameras in place, but in practice hardly relevant.
- Also on full frame good, although you should ask as the owner of a full-frame camera already, whether the use of a 'cheap lens' really makes sense. After all, who can afford a 5D etc., in my opinion should not save even the lens. One thing is certain: Both the Canon 24-70 2.8L, and the CANON 24-105 4L are better than the Tamron - though not at the price / performance ratio.
- Unbeatable for the price
Finally, let me say that the Tamron 28-75 2.8 is ideal for all those who take pictures with cameras Crop and plan the transition to low-cost full-frame or as I still occasionally work with analog equipment, ie old film camera. Because one can only buy time, the housing and later set if necessary still an L lens. Priced at only 360, - is really nothing lost ...