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10-22-2012, 12:14 PM   #1
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Tamron 17-50 2.8

I read that this is a great lens. I know some people get a bad lens and they have to switch for another copy. This is my second lens and I'm a real beginner. jhjh


My question is how do i know if my lens i got is a good copy? How do i test this lens and in future reference any other lens i get?
Thanks for any help you can contribute.

10-22-2012, 12:27 PM - 1 Like   #2
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All you need is a brick wall. If you've got a tripod, even better. Otherwise, use fast shutter speeds. You'll want to use low ISO to ensure that image noise isn't an issue.

Now just photograph your wall at various focal lengths and apertures. View the images at 1:1 in the centre, edges and corners. Are they acceptably sharp? If not, you can try adjusting the focus in your body. Check that the images are equally sharp on both sides (if they aren't, you have what is called a centering defect).

Note that you can't expect best performance at F2.8; you'll see peak performance at F5.6. This is to be expected.
10-22-2012, 01:01 PM   #3
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QuoteOriginally posted by infos Quote
I read that this is a great lens. I know some people get a bad lens and they have to switch for another copy. This is my second lens and I'm a real beginner. jhjh


My question is how do i know if my lens i got is a good copy? How do i test this lens and in future reference any other lens i get?
Thanks for any help you can contribute.
I agree with the previous poster, and at the risk of sounding a bit snide or snarky, I would say go out there, use it, and have fun! If you like the results, keep it. Even better if you have a more interesting subject than a brick wall that is still fun to take pictures of. For me, my dog is often my test subject. She's a couch potato and her fur is very fine so that helps me discern how sharp an image is.
10-22-2012, 01:41 PM   #4
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I was having a trouble finding a brick wall. The thing i have to look in the images is how sharp they are right?

10-22-2012, 01:50 PM   #5
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A brick wall is a two dimensional object.. if that's what you plan to shoot all the time, then it's agood thing to take picture of when you try out a lens. My 18-135 has terrible image border resolution at 100-135mm, but most of the time at those focal lengths the subject is in the center, and the background at the edges is out of focus anyway, so I don't care. And at 24mm when I'm shooting landscapes it's good edge to edge.

The simple way to judge a lens, take some pictures of the things you like to take pictures of, if the lens is good enough and the price is right buy it. Good enough, and price is right and both personal decisions we can't help with. If you're looking for "best possible" that gets a lot more complicated... you don't want to pay for best possible... at least I don't.
10-22-2012, 02:16 PM   #6
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QuoteOriginally posted by infos Quote
I was having a trouble finding a brick wall. The thing i have to look in the images is how sharp they are right?
You can also tape a newspaper to a wall. If I can't be arsed to get off my sofa, I use a bookcase. Brick walls are good because they have lots of fine detail, although they make extremely boring subjects.

As others have pointed out, you can also take pictures of the stuff that you like taking pictures of.

FWIW, I found the Tamron 17-50 to be an excellent lens, although overall build quality was a bit meh. For the money it's as good as it gets. I sold it to go towards a DA* 16-50 at 400 more which I ended up not liking very much. More fool me.
10-22-2012, 03:25 PM   #7
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Yeah, it's a little hard to tell whether your lens is a good copy, when you are just starting out, and you don't have many other lenses to use to compare the images.

If you have a good computer monitor, you can look at the images full screen. Most "defects" won't be too hard to see, like chromatic aberrations, or softness. Since you are just starting out, I think the 2-dimensional test is a good starting point. I'd say to primarily look for sharpness, mostly in the center area, don't worry about the edges too much.

If you think you see something wrong, you can also post some crops (a portion of the photo that is small enough that you can upload it without the web site downsizing it), and others will be happy to comment on whether it is okay.

You didn't say what other lens you already have to compare it to?
10-22-2012, 04:44 PM   #8
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My copy was great... I don't think you need a brick wall to tell if yours is good... Just take a bout load of pictures and have a look at them...

10-22-2012, 05:55 PM   #9
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I lived for a while where bricks were uncommon. I was really excited to move to a house with brick walls.

Yes, they are a pretty dull subject, but they will show one issue clearly: is the lens soft on one side, a clear manufacturer problem. Your camera's sensor has to be parallel to the wall for the test to mean anything. I'd set up a tripod at a reasonable working distance, get the camera level and plumb and parallel, focus carefully (Live View and CDAF if you have it) then take some shots wide open at each full stop through f11. It's pretty easy the second or third time. I like to compare the left and right sides particularily. The lens will not be as sharp wide open as it is at f8. If you have a little time, put the kit lens on and do the same test.

You can sometimes find testing sites or manufacturer data to compare your results to. If they show supersharp corners and you're not seeing that, it might be a problem.

Just shooting in an ordinary way with a lens should work, but it's tough for inexperienced users to judge whether some lens issue or their inexperience is causing trouble. Once you have some confidence in your abilities, brick walls aren't that helpful.
10-22-2012, 06:51 PM   #10
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I have a brick wall outside across the building. How close do i need to shoot to get some quality testing photos.
10-23-2012, 03:50 AM   #11
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I haven't ever done this and I haven't done any Google searches, but my first thought would be to stand about 8 feet away. I think it might also depend on the focal length, i.e. if you're wider, move a bit closer. But again, this is completely intuition on my part.
10-24-2012, 06:57 AM   #12
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Just go and take some pictures and see how sharp they are. They should be nice and sharp. If they are not sharp and your technique is not at fault, then there may be an issue with the copy. i have one for my Pentax and another for my Nikon (I know, I'm a bit crazy) and think that this is a wonderful lens.
10-24-2012, 04:21 PM   #13
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So far what i'm seeing is that is sharp. I took many pictures with a tripod.

My first lens is a 35 mm 2.4 prime. Now this lens is huge, i having a hard time taking steady photos. I know somethem have blurs but i think once i get used to it i'll be fine.
10-25-2012, 05:26 AM   #14
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QuoteOriginally posted by infos Quote
My first lens is a 35 mm 2.4 prime. Now this lens is huge, i having a hard time taking steady photos
many of my friends have Canon 5D xx with canon 24-70 f2.8...compared to canoners having about double weight than us we can feel feel happy to shoot with K5(or other pentax)+tammy. we also have SR
10-25-2012, 08:23 AM   #15
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I have this spot about 5 minutes from my house. I go there and shoot with every lens and check it out with a little pixel peeping. I'm on the wrong computer but I do have this shot handy of one of my first weeks shooting with the DA 15. It has a stone wall, rocks, old bridges, trees and a river.

Last edited by reeftool; 12-29-2016 at 04:45 PM.
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