Tamron 17-50mm non-VC, Sigma 17-50mm, Pentax 18-135mm

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jamesm007 Veteran Member • Posts: 5,793
Tamron 17-50mm non-VC, Sigma 17-50mm, Pentax 18-135mm
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Review of three kit lens upgrades. The Tamron 17-50mm f/2.8 non VC, Sigma 17-50mm f/2.8, Pentax 18-135mm f/3.5-5.6.

I acquired these lens over this year. I first bought the Tamron 17-50mm f/2.8. Its been a keeper, works perfect. This means to me, it never missis focus. Well its hit rate is a conservative 95%. The pics are sharp and usable from f/2.8 and up. I know if you get a lens like this don’t sell it because its sort of hard to get a perfect copy that works like the best review of the lens. The Tamron did. Next up was the Pentax 18-135mm f/3.5-135mm.

The Pentax is also a keeper for me. I am a bit shocked by its performance sharp through its whole range, never missis focus, it’s the best focusing lens I have it never really misses. So, in my mind I got lucky two lens that performed well. One lens that performed as the best review said it should, and the Pentax that performed way above the best most pro reviews said it should perform.

The Pentax is an outlier in the land of lens. Most pro-reviews that measured it showed poor border and corner sharpness. Its performs like it had sharp borers and corners. The Pentax has superb contrast and color and it seems sharp even at 135mm, corner to corner many times! It can’t be I know, just can’t be. But it is! It always seems to make the picture just right. Oh and its weather sealed. I leave it on my camera.

The Sigma is one of those lens that performs more like its poorer reviews. Its not a bad lens especially stopped down to f/4 or higher. But it misses focus at times, and the Sigma doesn’t like f/2.8. You really need to shoot contrast detect at f/2.8 to make sure you hit critical focus. Moreover, Its heavy to carry all day in one hand.

Of those three lens the Pentax DA18-135mm is the keeper, its just too good. The Tamron a close second, it doesn’t quite have the high level of contrast but makes up for it with high levels of MTF type sharpness. I never dreamed the Pentax would punch so high if I knew, I would have bought it long ago.

So a simple review, three good lens really. If I were to recommend a general purpose walk around with extra range for sure it would be the Pentax DA18-135mm f/3.5-5.6. Its so good even at high iso you forget your using high iso’s. Buy Tamron if you need a fast lens, it’s a solid lens. I took the Tamron and Pentax to Cranbrook House and Gardens in MI. It was a shootout between those two and it was a draw during that sunny day I had to look at the exif when I got home to see which lens took the picture. Again Tamron for speed, Pentax for extra zoom range which BTW 135mm is more telephoto than it sounds. It can get up close!

The below is the Pentax 18-135mm f/3.5-5.6mm, shot at 135mm iso640

Click Original Size to get a hi-res view and it does not look like photozones measurements taken at 135mm at least not IMO.

Pentax 135mm

 jamesm007's gear list:jamesm007's gear list
Pentax K20D Pentax K-5 Sigma 10-20mm F4-5.6 EX DC HSM Pentax smc DA 10-17mm F3.5-4.5 ED (IF) Fisheye Tamron SP AF 17-50mm F/2.8 XR Di II LD Aspherical (IF) +13 more
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