[awscreo]

So I bought the tamron 70-200 for my K-1 few weeks back, quite liked it and had some nice portraits done with it, and some sports. But, I've noticed that when I tried using it for landscapes, the left side of the lens, especially at the long end was always soft.

So I put it on a tripod, zoomed in to infinity, and tried shooting at different apertures. It's just always soft at the far left side of the frame. It's not a huge area, looks like about 6-7% of the entire image, but the right side is always the same sharpness as the center (or at least close to it, with wide open being softer obviously). So I thought lens was decentered, and sent it back to the shop I bought it from. They sent a replacement to me, it arrived today. So I tested it right away, and found the same problem, albeit seems a little better now. Soft far left at 200mm, right side is same as center. Thing is, I tried using other focal lengths, and it seems it's only a problem at the 200mm point, with 135, 100, 85 and 70 being consistently even across the frame (70mm seems a bit off too, but nowhere near as bad as 200mm, and I'm not as worried about it).

So, is the lens decentered, or it's just a quirk of this particular lens? I read that decentered lenses are soft at all focal lengths, is that true? Or is the lens miscalibrated at the long end? Please let me know what you guys think, I'm trying to figure out if I should send the lens back again and gamble on another copy, or ask the shop to send it to Tamron for calibration under warranty. Or just keep it and deal with the long end being like that? If anyone has a 70-200 tamron, can you please see if you experience the same thing @200mm or it's just my luck twice in a row..

Any input would be much appreciated!

PS: I think I slightly missed focus at 70mm 5.6, that's why image is a bit blurry. But again, mainly concerned about 200mm

I've put together a compilation of the focal lengths @2.8 and 5.6, can be viewed here (Taken with the new copy I've received today.):
https://s11.postimg.org/w46jap0xv/70_200_sides.jpg

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Last edited by awscreo; 11-07-2016 at 02:01 PM.

[fwbigd]

If only one side of the lens is soft it's decentered...

[awscreo]

If only one side of the lens is soft it's decentered...

Is it possible though that it's only affecting 200mm? Rest of focal ranges look fine to me (I've posted a link to a compilation of all focal lengths I've tested)

[Scorpio71GR]

Something seems off in those shots. The focus is completely off, maybe it could be atmospheric conditions but I am not sure. Are those crops of the edges? I do know a Tamron 70-200 should not look like that.

This my Tamron 70-200 @ 200mm and f4.5.


70mm @f5.6



For distant landscape shots, stopping down is essential. I would try some more shots under better conditions. With my copy sharpness definitely improves by stoping down to f3.2 of f4.

[awscreo]

Something seems off in those shots. The focus is completely off, maybe it could be atmospheric conditions but I am not sure. Are those crops of the edges? I do know a Tamron 70-200 should not look like that.

This my Tamron 70-200 @ 200mm and f4.5.


70mm @f5.6



For distant landscape shots, stopping down is essential. I would try some more shots under better conditions. With my copy sharpness definitely improves by stoping down to f3.2 of f4.

Those are 100% crops of extreme corners. I focused via liveview on a tripod, the only one I think I've missed is a 70mm 5.6 crop, focus is off on that one. The reason I was using 2.8 is because that's how I've seen people advising to test for defocusing. Look at the image again with those things in mind, all of the focal ranges seem fine to me except the 200mm. That's why I wanted to see people's shots at infinity at the long end on a full frame body, to see if my copy is decentered or it's just how the lens is.

The shot you've shared with the swans - the softness that I see with my copy would be way out of the frame because of the crop factor with APSC, as I said, it affects like 6-7% of the image, and only at that focal range.

---------- Post added 11-07-16 at 07:31 PM ----------

Someone's gotta have a long distance shot at 200mm? It's a pretty popular lens I'm leaning towards sending it to Tamron for calibration.. But if it's a common trait of this lens, it'll be a waste of time and money..

[victormeldrew]

Perhaps ever so slightly soft at the extremes...but certainly not decentred. I'm not sure any lens is decentred by design.

[normhead]

Send it back if you can still exchange it. It's not going to get any better.

[awscreo]

I can send it back, but I don't want to gamble on another copy and go through this process again. They offered a full refund. But I really like the focal range the lens offers, and sharpness at anything except 200mm.. I was considering sending it to Tamron to get fixed under warranty. Is it possible that Tamron could calibrate it to have consistent sharpness at 200mm? I just need 1 K-1 + Tamron 70-200 owner to show me a sharp uncropped photo at 200mm, and I'll send it to Tamron for fixups)

[victormeldrew]

I'm not much of a shooter of brick walls so can't find an image @200mm and wide open where the corners are all in the same focal plane. But wherever the focal point is, they are all pretty sharp, as most people have found with this lens.
It is not normal, it needs fixing, and if it's in warranty I don't understand why you wouldn't send it to them.

[Scorpio71GR]

I have known people to go through mutiple copies of this lens to get a good one. When do you get a good one you will not to let it go. I would check the K1 thread. I know of at least three people in the forums that have a K1 and are using this lens. For what I am seeing, your results are unacceptable.

[awscreo]

I'm not much of a shooter of brick walls so can't find an image @200mm and wide open where the corners are all in the same focal plane. But wherever the focal point is, they are all pretty sharp, as most people have found with this lens.
It is not normal, it needs fixing, and if it's in warranty I don't understand why you wouldn't send it to them.

I will send it for repairs, it's just it's a second new copy of the same lens with the same problem, I was wondering if it's a normal characteristic of the model. I've made more tests, it seems issue is only affecting left extreme side (7-10% of the entire image) at 2.8-8 apertures, at f10 it gets pretty close to the right side, and f11 being pretty uniformly even (albeit not as sharp as at 135mm or 170mm). I'm a little bit hesitant of sending it in, I'm afraid Tamron might decide that this is within the spec and send it back without doing anything. In any rate, I don't know if I'm expecting too much from the lens, i mean it's basically two and a half times cheaper than the Pentax 70-200. But it's so sharp at 200mm 5.6 in center and right side, especially with PixelShift, but totally soft and ugly on the far left, it just annoys me more than anything. It's totally adequate for portraits and any upclose work, but at infinity focus on a long side it's just a disappointment right now..

[normhead]

If you read through the reviews in the forum, yes it is. 10% of forum users have had to return this lens. One guy had to return it twice. ANd it is very unlikely that Tamron has the equipment to fix decentering on this or any lens, according to Lens Rentals .com.

Take your full refund and try and find it somewhere else.

[awscreo]

If you read through the reviews in the forum, yes it is. 10% of forum users have had to return this lens. One guy had to return it twice. ANd it is very unlikely that Tamron has the equipment to fix decentering on this or any lens, according to Lens Rentals .com.

Take your full refund and try and find it somewhere else.

Hmm, I guess it's too late. I called Tamron, they said they certainly fix decentered lenses under warranty and asked me to send it in. I sent mine in already, fingers crossed they fix it up. I mean even if they don't, what I find is that at f11 with pixel shift image looks fine, left corner is pretty consistent with the right one. I guess I'd be using f11-16 for landscape anyways, so even though it's a workaround, it's at least something. Other than that issue I love this lens, that's the reason I don't want to just give it up.

[normhead]

Hopefully they can do it. People who get a good copy of this lens just seem over the moon with it. Hopefully you can join them in their "over the mooness."

[awscreo]

Just FYI - finally managed to send my copy to Tamron with International warranty I've received from Tamron Canada. Tamron USA suggested to send my K-1 with the lens to tune up precisely for the body (they told me they do not have k-1 in stock to test with), which I did after a bit of hesitation. They've fixed it up in 2 business days and shipped it back to me very quickly. Unfortunately package got stuck on a fedex truck due to a massive snowstorm that has hit our area last week, but it's no one's fault so no biggie. Happy to say that lens is now very even across the frame at 200mm and all apertures, so my warranty experience was a successful one. Tamron was very quick to respond and very nice to deal with, helpful, informative and fast. Great to finally get my camera back, had withdrawal pains for a week lol, especially since my Pentax-A 50 1.4 arrived last week and I had no means to test it out)