Canon t3 and a Sigma lens trouble

Discussion in 'Photography Beginners' Forum' started by beetjuice, Jan 14, 2016.

  1. beetjuice

    beetjuice TPF Noob!

    Joined:
    Dec 7, 2015
    Messages:
    13
    Likes Received:
    0
    Can others edit my Photos:
    Photos OK to edit
    After much research (and some opinions on here) I bought a Sigma 70-200mm f2.8 lens for my Canon t3. The auto focus is off. I was reading on how to calibrate lenses to cameras with things like the Focus Pyramid, but I can't seem to find the option to calibrate in this camera. Am I missing something? Is there a way to calibrate these two together? I have two other lenses for this camera that do not have this problem (both Canon lenses). I just received this new Sigma lens in the mail 2 days ago, so I know I have to get used to it. However, I feel like the AF just isn't focusing. If this seems like it's faulty on my end of using it, please let me know. If I can't fix this problem, I will return the lens.

    Here are some photos unedited:

    IMG_4168

    IMG_4180

    IMG_4182


     
  2. vato_loco

    vato_loco TPF Noob!

    Joined:
    Dec 14, 2015
    Messages:
    26
    Likes Received:
    3
    Can others edit my Photos:
    Photos OK to edit
    There's always the chance that the lens itself is faulty, you know. If you have the chance to ask for a replacement, consider it an option.

    Also there's a thread on dpreview where it is established that the T3's sensitivity is limited to f/5.6, but I'm not sure that's what affecting your pictures. Try to take a picture with the Sigma with a f/5.6 or even f/8 aperture and see how it goes.

    Here's the thread in question: Autofocus performance with EF primes on 1100d / Rebel T3: Canon SLR Lens Talk Forum: Digital Photography Review
     
  3. KmH

    KmH In memoriam Supporting Member

    Joined:
    Apr 9, 2009
    Messages:
    41,401
    Likes Received:
    5,696
    Location:
    Iowa
    Can others edit my Photos:
    Photos OK to edit
    I don't think the Canon T3, Canon's most basis DSLR in it's day, has a focus fine tuning (calibration) feature built into the camera.
    Putting a 3rd party lens on your camera is more likely to be problematic than using a Canon made lens.

    Sigma would have to adjust the lens, if you keep that lens.
    Every mass produced lens maker has some variability in performance from lens to lens.
    So you could have had the same issue had you bought a Canon 70-200 mm f/2.8

    So I would say you have two options:
    1. Send the lens back to Sigma for a warranty adjustment/repair.
    2. Send that lens back, but you might get another one that also isn't quite right when auto focusing.
     
  4. Overread

    Overread has a hat around here somewhere Staff Member Supporting Member

    Joined:
    May 1, 2008
    Messages:
    24,679
    Likes Received:
    4,461
    Location:
    UK - England
    Can others edit my Photos:
    Photos OK to edit
    First step is to eliminate user error as much as possible as a factor:

    1) You want a tripod, a surface (like a wall or floor) at 45 degree angle to the camera (ideally something with markings - or with a ruler).

    2) You want to take shots in good light with the aperture wide open (smallest f number) so that you've got the thinnest depth of field.

    3) You want to use single point AF in the middle point of the camera.

    4) Take the shot, using the markings on the surface to note which mark you aimed the focus at and it locked on then compare to the final shot and see if the mark lines up with it


    By using a flat surface and a camera and subject which are totally static you remove blur as a factor (either hand shake or motion blur). You further allow yourself to see the degree of error (if any) on the markings. This test also lets you see the build up and drift away from sharpness, telling you if the softness you're seeing is a focusing issue or softness in the lens itself.

    Repeat the test at different apertures keeping the AF point on the same location to get a better idea of lens sharpness performance.



    For a zoom lens repeat the steps for the short end and the long end as there can be a variation between the two.


    From there you'll have data that should remove motion and user error and give you some idea of what is going on.

    Camera and lens wise it could be that your lens is not well calibrated to your camera in either sharpness/focusing or both. This could be a manufacture error or a simple case of calibrations being out of sync (cameras are also made within calibration tolerances).
    If it is the latter then you can send it to Sigma for warranty repair; however be mindful that if you only send the lens it could come back with its calibration adjusted and still appear soft (this is more likely with overall sharpness than focusing errors). That's because (as said above) calibrations are within tolerances and this without your specific camera body the techs might calibrate the lens even further away from your camera on the scale.
    Thus the best is to send camer and lens to Sigma for recalibration of the lens to the specific camera (s) you use. OF course this is often not a practical option, even for hobby photographers. So what approach you take depends on what results you get and what options you feel are open to you.
     
  5. zombiesniper

    zombiesniper Furtographer Extraordinaire! Supporting Member

    Joined:
    Jun 23, 2015
    Messages:
    6,907
    Likes Received:
    4,741
    Location:
    Angus, Ontario
    Can others edit my Photos:
    Photos NOT OK to edit
    As much as I'd like to see one the rebel series cameras do not have a lens calibration feature.
     
    • Winner Winner x 1
  6. beetjuice

    beetjuice TPF Noob!

    Joined:
    Dec 7, 2015
    Messages:
    13
    Likes Received:
    0
    Can others edit my Photos:
    Photos OK to edit
    Thank you everyone for the quick replies. I contacted Sigma - I haven't heard back from them yet. At the time I was looking for a new lens, I was also considering the Canon 70D body after talking to a sales rep at B&H Photo. But I decided to go with what I was taught - if you have a budget, save your money for the nicer lens. Now after this, I'm now considering the 70D even more. I'll update when I hear back from B&H.
     
  7. beetjuice

    beetjuice TPF Noob!

    Joined:
    Dec 7, 2015
    Messages:
    13
    Likes Received:
    0
    Can others edit my Photos:
    Photos OK to edit
    Just got a reply:

    Hello Kelly,
    If the camera and lens combination gives you sharp images when using the Live View focusing feature of the camera then you have a slight misalignment in your cameras viewfinder focusing system, we can correct that with an AF Data adjustment to the lens. The service on the 70-200mm would cost $135 and be completed within 24hrs. of the receipt of payment. Are you’re the original owner of the lens?
    Sincerely,
    Paul Pizzano
    SIGMA Corporation of America l 15 Fleetwood Ct, Ronkonkoma, NY 11779
     
  8. Overread

    Overread has a hat around here somewhere Staff Member Supporting Member

    Joined:
    May 1, 2008
    Messages:
    24,679
    Likes Received:
    4,461
    Location:
    UK - England
    Can others edit my Photos:
    Photos OK to edit
    I would expect if you're the original owner and if its a recent purchase that it should be a warranty repair as it should be fit for use from purchase; which I suspect why he's asking if you're the original owner. Helps if you've got a receipt for the purchase too as proof (if you don't have one contact the retailer where you got it from; most keep records and can produce another copy if needed
     
  9. weepete

    weepete TPF Supporters Supporting Member

    Joined:
    Oct 18, 2011
    Messages:
    4,658
    Likes Received:
    1,526
    Location:
    Glasgow, Scotland
    Can others edit my Photos:
    Photos OK to edit
    Why do you think the AF is off?

    Your settings look a bit strange to me: 1/4000th sec at F4 and ISO of 3200 or 6400 at 200mm. A lot of those shots look like you could have used 1/500th of a sec (with os turned off if the lens has it) and traded that for lower ISO and more depth of field.

    Your shots look pretty much like what I'd expect at those settings, and to me the focus looks ok. Possibly a bit of front focusing but it depends what AF point you used.

    anyway if you want to test your focusing and sharpness you need a static subject like overread suggests. I've used a diagonally placed level (yellow so higher contrast than a meter stick) with millimeter measurements to test the focus on my 150-600 before But, you need to eliminate other points of error to diagnose it. So tripod, mirror lockup, single point AF, static subject, low ISO, good light, one shot are all needed to avoid other issues and see if your lens is properly out.
     
  10. beagle100

    beagle100 Been spending a lot of time on here!

    Joined:
    Mar 31, 2015
    Messages:
    1,992
    Likes Received:
    510
    Can others edit my Photos:
    Photos OK to edit
    you're shooting directly into the sun
    try focusing on something with the sun at your back (pointing towards the subject)
     
  11. Derrel

    Derrel Mr. Rain Cloud

    Joined:
    Jul 23, 2009
    Messages:
    44,054
    Likes Received:
    16,749
    Location:
    USA
    Can others edit my Photos:
    Photos OK to edit
    OMG---$135 to calibrate an older Rebel to a faulty Sigma lens? Just say, "No, thank you."

    No way!
     
  12. beagle100

    beagle100 Been spending a lot of time on here!

    Joined:
    Mar 31, 2015
    Messages:
    1,992
    Likes Received:
    510
    Can others edit my Photos:
    Photos OK to edit


    right, the OP rejected the outrageous Sigma "calibration"
     
    • Like Like x 1

Share This Page