Tamron 17-50 2.8 VC : Soft at 17 mm and f/2.8 in low light

Discussion in 'Nikon' started by nishnishant, Dec 31, 2009.

  1. Okay, here's some background first : I got the Tamron 17-50 VC a few weeks ago, and after getting the F-- error on a few occasions, I exchanged it for a new one (actually, I returned it, and ordered a new one).
    Today I used the new lens and noticed that when I shoot it at its widest focal length (17mm) and at f/2.8 aperture (very low indoor light, needed ISO-1600 and still got 1/20-1/40s) - focus is very soft.
    Initially I thought this may be a front (or back) focus issue. But I don't get it when I use flash. And I also don't get it when I zoom into a longer focal length (24mm or more).
    I checked out some of the pics I took with the lens I returned, but I couldn't make a direct comparison because with that lens I don't seem to have taken many at 17 mm and f/2.8 in low light. (most of those pics were in decent light).
    I tested with a smaller aperture (f/4) and the softness seems to improve (gets less soft).
    So is this normal for this lens? Or is this a back/front focus issue? I've already done one exchange, and I hate returning and exchanging stuff!
    Thanks for any advice.
     
  2. Ok, and this is a bizarre observation. When the subject in focus is on the central focus point (this is a D-80 by the way) focus seems sharper. It's when the subject is in one of the side focal points that the softness is more prominent. Not sure if that's just coincidence.
     
  3. I have no idea, but most people will need you to post the pictures to be able to help you.
    happy new year!
     
  4. Unfortunately I can't post my pics from today (the subjects in the pics are not comfortable with that).
    I intend to take some test shots with my son's toy figures to see if it's one of these :
    1. an auto focus issue in low light
    2. front/back focus
    3. the lens simply being soft at 17 mm and f/2.8 when ISO is high
     
  5. Okay, here are some samples I took (seems to be a focus issue here) :-(
    This one is the full image (resized to 700 pixels width). Focus was on the middle toy on all these samples (the toy with the raised hands).
    00VNvY-205409584.JPG
     
  6. Here's a 100% crop of the above image showing how the focused subject (the center toy) is all soft and out of focus.
    00VNva-205409684.JPG
     
  7. Here is another sample, taken from slightly farther away - this one is the full image.
    00VNvb-205409784.JPG
     
  8. And here's a 100% crop showing the subject in focus (or rather completely out of focus and blurred)
    00VNvc-205409884.JPG
     
  9. Looks like I am going to have to return this lens too :-( This time though, I think I am done with Tamron lenses. What a disastrous way to start the new year!
     
  10. I don't have your lens, or a D80, but your pictures look OK. Do you have a lens that produces better results under the same conditions?
    From your post, it appears to me that your testing procedure is flawed. Are you testing the lens optics, the VR system, the camera ISO, or the auto focus? To obtain useful results you have to isolate the variables.
    VR systems are difficult to test. Different people shake differently, and VR cannot compensate for forward / backwards movement. Different shutter speeds and focal lengths will obtain different results with different people and techniques. Do you know what your lens will resolve at that aperture without any camera shake?
    Is this a camera problem? Use the same aperture, VR off, a tripod, shutter release and different ISO's to determine if the ISO is to blame for the softness.
    Is it the AF system? (not likely from the images) Use good technique combined with AF, compare it to precise manual focus.
    Is it the aperture? You didn't pay for the Nikon 17-55mm, wide aperture performance is what you pay for. Stop it down, does it get way better (I think you've seen that).
    It's probably a very good lens, There is a lot to learn about taking pictures, and lens testing.
    My 2C, Stan
     
  11. I just returned my Tamron 17-50 2.8 VC this week for even worse performance then you describe. I tested my lens over several days and a couple hundred exposures, indoors low light and with flash, outdoors in daylight and I don't think any could be called sharp, certainly nothing like what others have raved about this lens. Indeed, corners and out of focus areas exhibited double imaging and flare. I think it must have been a bad copy (quality control issues at Tamron?). I'm willing to try again with a replacement if Adorama sends me one, otherwise I'm gonna have to shell out the bucks for the Nikon.
    It's a pity because I really like the feel and balance of the lens as it suits the D90 particularly well.
     
  12. Stan,
    I do agree that my tests were imperfect but I did not base my opinions on just those tests. Typically, I have this very basic expectation of any camera/lens. Once I lock the focus on the subject, and I take a shot - then, ignoring camera or subject movement, I expect a reasonably sharp image. I have been able to do that with my Nikon 50 mm 1.8 AFD lens, and even my old D40x kit lens (18-55 non-VR), and now that I've gone through the pics taken with my first Tamron copy (the one with the F-- error), I find that even that lens took much sharper pictures.
    In many of the pics that were ruined yesterday, there were 1-2 people standing 12-15 feet away from me, and after focusing on them and taking a shot, I find that they are all soft or not in focus. Admittedly this could be a VR-failure (but the previous F-- Tamron copy did a far better job there).
    And while my photography technique might be erroneous or flawed, the same technique gave me much better photos before (with other lenses as well as with the returned Tamron copy).
    And finally, I agree, getting the Nikon 17-55 would probably have been a much better idea, but at double the cost and without VR, I am now wondering if I should just upgrade to a D-90 and use the 18-105 VR kit lens. With the two added ISO stops (I think I can go up to 6400 with hi-mode in the D-90 and get similar quality as the D-80's 1600), and the VR, it wouldn't be too bad an idea I guess.
     
  13. Peter,
    Thanks for the feedback/info. Whenever we travel somewhere, one of the most important aspects of the trip for me is the pics I take. I usually can't wait to get back and transfer the pics and re-live the moments. So yesterday was very disappointing for me.
    Yeah it's a pity because I like the lens too (at least the older copy that I had to return because it has the F-- error). I just don't want to waste my time (and probably Amazon's time too) by returning/exchanging lenses till I get a good copy.
     
  14. Nish,
    To me, it looks like a backup-focussing lens. The doors behind do seem significantly sharper than the toy, judging from the posted examples. Maybe check that?
    As for a D90 at ISO6400 and a slow lens: no. The ISO1600 of the D80 is not great, but not that bad. ISO6400 on a D90 is pretty bad; realistically you win one stop with the D90, not two.
    But even that is still half the story: f/2.8 allows far more creative choices (with regards to the DoF) than f/5.6 ever will. No matter how far high ISO performance is improved, nothing will ever replace fast lenses for their ability to isolate subjects.
    Sorry 2010 begins like this, I hope the rest of the year will bring lenses with stellar performance and many oppurtunities to use them!
     
  15. Thanks Wouter. I took a few more test shots and also re-examined my earlier shots. It does seem to be a back-focus issue rather than a front-focus issue. I googled about this and found that apparently this has been a not-so-rare issue with the older non-VC versions too.
    And yeah, nothing like a wide aperture to get some really neat shallow DOF shots. Also one thing I hate about the variable aperture lenses is that when you've set it to the widest aperture and then you zoom in, the aperture changes (not a problem with a constant aperture lens). And thanks for that info about the D90's 6400 ISO performance (I guess I had an exaggerated idea about the ISO performance of CMOS sensors then).
    >> I hope the rest of the year will bring lenses with stellar performance and many opportunities to use them!​
    Thanks for the wishes. I hope so too. And you have a great 2010 too, Wouter. :)
     
  16. While I am not a Nikon person, if you focused on people and then moved the camera for composition that could be creating the problem as the distance from the people changes so that the camera will no longer have an accurate focus, think of a right triangle. This is specially true when using a wide open aperture as the dof is very narrow.
     
  17. Why does everyone shoot tests in low light? That just adds a bunch of other reasons why the shot could be soft. Shoot a test in full daylight wide open with aperture priority. That will eliminate camera shake or focusing problems in low light and tell you if the lens itself is sharp. Once you know that, you can experiment to see how accurate the auto focus is in varying degrees of low light. But focusing on tiny toys in a dim, plain room isn't going to be easy for any lens.
     
  18. @Manuel : yep, I am aware of that. I made my subjects stay still, locked focus and took snaps to verify that that wasn't what was causing the softness.
    @Stephen : good point, and I do intend to test this out in bright light (daylight) before deciding on whether I should return it or not. But my opinions were based on the relative difference between pics taken with this lens and pics taken with other lenses including the older Tamron copy. I managed to locate a few pics I took with the bad Tamron (with the F-- error) and those pics did not have this softness problem.
     
  19. Incidentally, one new theory I have is that this may have something to do with the VR. The older Tamron copy that I returned had different VR behavior.
    Old copy : when I focused on something, the focus would lock and about a second later the entire image in the view finder would jerk slightly (this is the VR locking). After that silence till I press the trigger.
    New (current) copy : I focus on something, focus locks, and almost instantly there is this continuous motor sound (feeble) which seems to be the VR mechanism. (this feeble noise is not there when I turn VR off). Noise stays until I press the trigger.
    So seems that the VR behavior itself differs between the two copies. Of course that may not have anything to do with my softness problem, but just mentioning it here in case anyone runs into this in future.
     
  20. I got rid of a lens Nikon 80-200mm f/2.8 AF-D, was sent to Nikon which I paid a assessment fee unlike USA. Came back within specs.
    I had the lens for 2yrs, all my other lenses are sharp but not this one.
    I think people over complicate focus test. Tripod on timer in good light in daytime shoot something flat with heaps of texture like a window curtain. Open on computer and compare the same method with another lens. You can shoot at wide open and close up to test its close focussing.
    If you are shooting portraits and events and sports on the fly, do you really need to employ the most rigourous scientific approach ....
    If the same apporach works for others lenses then why not this lens. There may be exceptions thou some 3rd party lens models are not great at wide open but once a stop down they are good.... AFAIK this Tamron is said to be v good, I have seen pictures from others to say the same, I had thought about this lens for a DX body and as a good lens at a bargain price.
    Always use their warranty service.....
     
  21. I see you now have the new copy. Good now?
     
  22. Ray,
    Old copy refers to the lens I bought in early December that I returned after 3 weeks because it developed the F-- error (the error was random but repeatedly occurred several times).
    New copy refers to the lens I got just a few days ago. This one hasn't given me the F-- error yet although the old lens only started giving that error from week-3.
    The old copy pics are all sharp and good (I was very happy with those). It's just the new copy that gives me soft images. Unfortunately the majority of my old lens images were in good light so I don't have several images where I can compare the old and new lenses (though that really does not matter much).
    I went and took a nap because I was feeling down about all this. And I have also given this a lot of thought. My conclusion is that eventually, highly technical optical tests don't matter as much as whether you (as the user) are happy with the pics that come out of your lens/camera combination.
     
  23. I had one of those lens for my Nikons. Focus is indeed very soft wide open - shooting at infinity at 50mm. At first I thought it was my D90. But after trying it on the D200, D50, and D300 I can pretty much confirm that it's the lens. The AF fine tune on the D300 cannot correct the soft focus either. Luckily I have gotten rid of that lens.
     
  24. Paul,
    Did you have the new VC version too?
     
  25. what technique did you use? did you move the focus point to the toys while on the frame? or did you pre-focus and recomposed? what metering did you use? it might not be the lens. it could also be metering/focusing issues of the D80.......and sadly, again, technique?
    btw, even the nikon 17-55mm is soft wide open at f/2.8. i opted to use the sigma 18-50mm f/2.8 against the tamron 17-50mm. a lot better, in my opinion. of course sigma also has lens issues.
     
  26. Nish: STOP PIXEL-PEEPING!

    You will get wound up in this and never take a picture without worrying about focus or whatever. First of all, the Tamron 17-50 has (as all reviews have noted) some very visible curvature of field wide open. It's part of the design tradeoff for a fast zoom. Thus, if you use the central AF area to focus, then re-compose to place the subject away from center, it will look soft. That is the law of optics, not a copy-specific defect. It is NOT back-focus, front-focus, side-focus or even hocus-pocus-focus.

    If you MUST test a lens, you have to follow a very rigorous procedure. Here's one way. Get a 4x6 foot piece of plywood. Glue pages of sharp text (magazine pages, laser prints etc.) with various colors in the corners, edges, center and partway out. Put a small plastic mirror in the EXACT center. Now hang the target you have made so that it is precisely vertical. Place your camera on a tripod so that you see its reflection in the viewfinder, while filling the frame with the target. Make a series of exposures at varying f-stops and focal lengths. No UV filters, and use soft even light, like an overcast sky. Use a grey card to set exposure, so your images will have the correct contrast. Compare the images in your RAW converter with sharpening turned OFF, then with various values of sharpening.

    Do I do this? Nooooo. Life is too bloody short. And, even with this procedure, there are too many variables. Visual acuity, auto-focus errors or camera body modules out of tolerance...

    I notice you do not have a portfolio, on PN or elsewhere. Were I in your shoes, I would go and take pictures. This is not meant to deprecate--we are not judged by our lenses, but by the effect our images have on others.
     
  27. I don't know about your other shots, but in these two shots the camera simply seems to have focused on the doors behind the toys. Remember that the AF sensors are linear and much larger than the squares in the viewfinder.
    And the distance seems too large to be a back focus issue, don't you think?
     
  28. Hey guys
    first of all sorry for my bad english
    its an old topic but i ve the same issue with my tamron 28 75 and pentax k-x
    and decided to join photo.net to write that :)
    actually Les u are right maybe Nish doesnt have portfolio
    but its obvious that he s not happy and not comfortable with his equipment
    and when u are not happy with it u dont go and take photos or share them with others
    i dont think its pixel peeping
    maybe he simple needs to be said that
    "hey Nish sorry this lens or all dslrs suck in low light or hey come on maybe u bought a fast lens but u cant use it at the widest aperture stop it down man :) or fire the flash no matter how clean ur images at high iso settings :D"
    anyway i took some photos with my compact camera and with my tamron lens and decide that
    dslrs of course better but when u wanna shot about 5 meters with wide angle that dof stuff may cause problems with aps c sensor and for small 1/2.3 " sensors focus on everytime cuz they dont have any other choice becuz of depth of field lol
    whatever i really wanna learn what did u do with that tamron lens :)
     

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