I was actually quite surprised by the performance of this lens. I didn't really expect a 13.9x zoom to be very good, and indeed it does have some limitations, but it did better than I expected, especially at the wide end of the range.
The consequence of squeezing such a wide optical range into such a small physical package is that some optical compromises must be made. The lens isn't fast at the long end. It's f6.3 from 200mm to 250mm. It shows significant vignetting at 18mm and some degree of vignetting throughout the zoom range when used wide open. Barrel distortion at 18mm is quite high, but diminishes at longer focal lengths and between 28mm and 250mm there's slight pincushion distortion.
Of course distortion and vignetting can be digitally corrected. As I've commented before, they are more serious problems if you're shooting film. Since the Tamron 18-250mm F/3.5-6.3 AF Di-II LD Aspherical (IF) Macro can only be used on APS-C digital SLRs, film use isn't a concern.
Optical performance is pretty good at the shorter end of the range, with good center and reasonable edge sharpness and well controlled chromatic aberration. Performance is quite similar to that of the Canon EF-S 17-85/4-5.6 IS USM over the same focal length range. At longer focal lengths the edge quality diminishes somewhat and chromatic aberration becomes more visible, but center sharpness holds up well. Though the lens is certainly quite usable, the image quality doesn't quite match that of the Canon EF 70-300/4-5.6IS USM. Of course the Tamron sells for under $500, while the pair of Canon lenses would cost you around $1070, weight more, take up more room in your camera bag and mean you had to switch lenses!
At an introductory price of close to $500, the Tamron 18-250mm F/3.5-6.3 isn't cheap, but it does include a lens hood and a standard 6-year warranty. For those who value convenience more than absolute optical quality and for those who simply don't like changing lenses, the Tamron 18-250mm F/3.5-6.3 isn't a bad choice.
The Tamron 18-250mm F/3.5-6.3 AF Di-II is available for Canon EOS (Digital Rebel XT/XTi, EOS 20D/30D) DSLRs, Nikon DSLRs, Sony (Minolta) DSLRs and Pentax DSLRs. Given the length and speed of the lens (250mm f6.3) the in-body stabilization features of the Sony Alpha (A-100) and Pentax K100D / K10D could be very useful. You could get a Pentax K100D + Tamron 18-250 for under $1000 and have a pretty nice "Point and Shoot" Digital SLR with built in image stabilization, a zoom range wide enough for almost anyone and better image quality than any small sensor digicam.
|Canon EOS Mount||Nikon Mount||Sony/Minolta Mount||Pentax Mount|