Am I Just Being Nit-picky, Or should I return This Tamron 28-75 Lens?

[joelh47]

<p>Based on many glowing professional and user reviews, I purchased a Tamron 28-75mm f/2.8 XR Di lens for my Canon 5D. I wanted a faster "normal" zoom to replace, or at least supplement, my faithful old Canon 28-135mm f3.5-5.6 IS lens, but didn't want to spend the money for a 24-105 f4L or a 24-70 f2.8L. Upon receiving the lens, I did a fairly thorough test of corner and center sharpness at various apertures and focal lengths. Although most areas of the frame compared very well, I was very disappointed with the sharpness in the upper left corner. You can see what I mean from the photos in the following folder.<br /> http://www.photo.net/photodb/folder?folder_id=929393<br /> <br /> These samples were all at 28mm and f4. I included crops from both the upper left and upper right corners. The upper right shows nearly equivalent sharpness between the two lenses, but the Tamron is clearly inferior in the upper left crop. It is even worse at f2.8. I included the (almost) full frame crop for both lenses at the end of the sequence, so you can see that otherwise, the Tamron is as good, if not better than the Canon. I do like that the Tamron seems to have less barrel distortion at 28mm, and less light falloff in the corners. By f8, the difference in the upper left corner sharpness is just about gone, while the rest of the frame remains as good as, or better than the Canon.<br /> <br /> My question is, am I nit-picking too much over this loss of sharpness in one corner of the frame at f5.6 and lower, or is this fairly common for this Tamron lens? In other words, if I wanted to try to get a sharper copy, is it worth sending this one back to B&H and trying another one? Or would I possibly be trading one problem for a different one? In my research before buying, I was aware that there was some variability between different copies of the lens, but I didn't expect it to be this extreme. Also, one of the reviews I linked to from photo.net, http://www.the-digital-picture.com/Reviews/Tamron-28-75mm-F-2.8-XR-Di-Lens-Review.aspx, seemed to describe my current copy of the lens perfectly. Again, I didn't expect the loss of sharpness in the upper left corner, as described in the review, to be as severe as what I've actually observed.</p>

<p>I would appreciate any opinions.<br /> Joel Holcomb</p>

<p> </p>

[david_amberson1]

<p>You could send it in. Wont hurt, the rest of the images look pretty good. The center and right side in those images look sharp. I did see what you mean in the upper left corner, but it seems worse in the first image than the rest. Hard to tell without seeing at 100%. Overall the lens looks like a good performer.</p>

<p>Whats it look like shooting real images. Are you pleased. Also, try 2.8...is it worse....I suspect so. Its important that the lens perform well at f2.8, cause thats what you bought it for. I have read from some users here about another lens they had that wasnt sharp on the left like the right. Said all their pics were very uneven in sharpness, sent it in and they repaired it....I think an element misalignment or something. I am thinking it was a 17-40 f4L that did that. If it can happen to a Canon L, then something that odd can happen to a Tamron for sure.</p>

[picturesque]

<p>The left side is the Achilles heel of the lens. It is the first part to go out of alignment and on some lenses, I am sure it is worse than the right side. I have two copies of the lens (for my 5D). One I bought used after the previous owner had it overhauled by Tamron, and the second I bought new. I used the first lens quite a lot, and after about 2 years, the barrel got sloppy and the left side went out. I am not complaining because I use it a lot--I shoot weddings every weekend.</p>

<p>I purchased a second copy new while I had the old lens overhauled. The new lens was pretty sharp on both sides, with the left side slightly worse, but very slight. When I got the old one back, it was as good as the new one, maybe better.</p>

<p>You have to ask yourself whether the left weakness (which is hard to tell with online samples) is important to the type of work you do. For weddings, it just isn't. I don't put people anywhere near the upper left corner (particularly at 28mm) that I expect to be sharp.</p>

<p>The very slight softness at f2.8 is to be expected of any lens, plus it is typical of this lens. You will find it sharpens up nicely in post processing.</p>

<p>I would consider getting another copy just to test side by side, and then send one back.</p>

[a._n.k.]

<p>The good news is Tamron has a 6yr warranty. Depending on when you bought it, you could send it into Tamron now... and even send it back 4-5yrs from now.</p>

<p>You could send it back to B&H, but might run into the same problem. Not sure what B&H replacement/shipping policy is but might as well pay shipping once, directly to Tamron.</p>

[joelh47]

<p>Thanks guys. David, the crop showing the blurry corner is at 100%, so in the "zoomed out" frame, it's not that noticeable, unless you are looking for it, which I was of course, since I was evaluating the lens' sharpness at different points in the frame. I have a bit of a reputation of sometimes going into too much detail, but that has often paid off in not blowing something that required real accuracy. I was an electronics technician before I became a photographer, so it goes with the territory.</p>

<p>Nadine, you told me what I needed to hear, that this is a common flaw in this lens, but that it can be corrected, or at least improved, by Tamron. Overall, I do like the lens, and will probably keep it as long as it can be fixed if the softness in the UL corner ever becomes an on-going issue. I do mostly portrait photography professionally, where, as for your weddings, it's fairly easy to avoid putting anything important in that corner. For the landscapes and macro work I do, I use different lenses anyway.</p>

<p>A.N.K., I think your advice is good too, and hadn't really considered the multiple shipping charges in trying several copies of the lens. Tamron's 6 year warranty was a factor in my purchase of this less expensive lens.</p>

<p>Joel</p>