Originally posted by redpit For the friend who was asking about Tamron 70-200/2.8 images with the K-1. The Tammy lens is one of my favourites and after the initial AF problems that I managed to overcome (with the Tamron service support) it performs excellent. The center resolution and sharpness is amazing for a zoom lens. Up to now I used it on my K-5IIs and on the crop sensor the peripheral IQ degradation was negligible. On the K-1 there is significant loss of IQ and much CA and aberrations as you move from the center to the edges of the frame. Even stopped down the lens suffers from obvious peripheral IQ degradation. So as I said earlier its up to you to decide what do you want this lens for and if it matches your shooting style. For me that I care mostly for the center performance, it is a great lens. Now with the K-1 its AF performance and speed is even better and that is another plus!
The peripheral IQ degradation is more evident in some focus lengths than others. At the shortest end 70mm I think is the most severe. Here is a picture that shows what I'm talking about. Not the best (maybe even some motion blur) but it is a good example and that is why I attach it. After I mounded my Tamron on the K-1 I feel that maybe it is also a bit decentered, as there are more problems on the right side of the frames than on the left... The original picture and 3 100% crops from it (center - middle border left - middle border right, all from the original OOC Jpeg with no PP):
It appears to me that you have a defective lens; the reviews on that lens with full frame don't mention those sort of problems, and I don't see any indication from other system full frame shooters in the past that they have those issues. It is possible that in repairing your lens that Tamron service may have decentered an internal lens element.
Do any of the rest of you Tamron 70-200 shooters see these kind of issues with your lenses?
Here is a quote from one of the reviews of that lens:
"The Tamron maintains its excellent performance on full frame; it benefits from the usual advantage of higher perceived sharpness on the larger format, and chromatic aberration, falloff and distortion are all within acceptable limits. It's at least a match for the Canon 70-200mm F2.8 L IS USM in terms of sharpness across the range, and indeed is noticeably sharper wide open at 70mm."
Last edited by HoustonBob; 05-07-2016 at 08:04 PM.