20d focus issues

Discussion in 'Digital Discussion & Q&A' started by Sharkbait, Aug 24, 2005.

  1. Sharkbait

    Sharkbait TPF Noob!

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    Any other 20d owners having problems with the AF system? I just got a new Sigma f/2.8 short zoom (their new EX series), and in low light it focuses perfectly on my 300d, but put it on the 20d and every single image is back-focused. :? :x
     
  2. ksmattfish

    ksmattfish Now 100% DC - not as cool as I once was, but still

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    It's all over the web, and there are lots of theories and explanations. I haven't been happy with my 20D AF either. I only use the center AF sensor. I've been mostly shooting with a Sigma 18-50 f/2.8 and a Canon 85 f/1.8; it does seem to be a bigger problem with the Sigma lens, but it's there with the Canon lens too. When I do the ruler test (photograph a ruler at a 45 degree angle) it seems to be working fine, but in the field it doesn't seem to be very accurate. One explanation is that the actual AF sensors are much larger than the indicators in the viewfinder.

    Maybe after the fall wedding season I'll send mine in to be checked out. All I know is that the AF on my Pentax ZX-5 (circa 1997?) works circles around this 20D. I installed a split screen, and now I'm back to 100% manual focus.
     
  3. Sharkbait

    Sharkbait TPF Noob!

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    You installed a split screen in your 20d? How'd you do that? I'm probably going to send mine in after the wedding season as well. Right now I have a $500 sigma paperweight. :|

    We're switching over to 1dMkIIs in our studio...I'd love to be able to up to one of those.
     
  4. Sharkbait

    Sharkbait TPF Noob!

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    What's odd is I put the 18-55 EFS p.o.s. kit lens from my 300d and the 20d will focus in zero light. Put on the $500 Sigma digital EX series lens and it won't focus in broad daylight. :| But put the Sigma on the 300d and it works great. So for the time being it looks like the 300d is going to be my primary body at weddings! :?
     
  5. JohnMF

    JohnMF TPF Noob!

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    ive had this prob too with my 20d and sigma lens, im really close to buying a new lens but if its the camera i might hold fire.

    How did you get the split screen too?
     
  6. ksmattfish

    ksmattfish Now 100% DC - not as cool as I once was, but still

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    Check out

    http://www.katzeyeoptics.com/

    There are other screens available. Some are cheaper. If you search there are big debates on which are better. I have the Katz Eye, and it works well, but it's the only one I've ever tried. The viewfinder is still too small.
     
  7. danalec99

    danalec99 TPF Noob!

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    FYI they are replacing that model with 1D Mark II N.
     
  8. Bosscat

    Bosscat TPF Noob!

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    Don't go ask anything about this at the Canon forum. They'll just say that your at fault, not their beloved Canons. I am lucky to get 30-40% keepers with this camera.

    Look on the bright side though folks. If this was a film camera, it would put you in the poor house.

    Had my Sigma F 2.8 70-200mm EX APO HSM sent back to make sure it was compatible with a DSLR and the song remains the same.
     
  9. ksmattfish

    ksmattfish Now 100% DC - not as cool as I once was, but still

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    I don't know if it's the same Canon forum, but I was visiting one where it was generally held as truth that you couldn't be a pro without the vertical grip, and that it was impossible to photograph almost anything without AF. The forum was all about gear masturbation, and had very little about actual photographs.

    Don't get me wrong, obviously my large collection of cameras demonstrates that I am quite turned on by camera gear, but I can seperate my camera fetish from where my good photos come from.
     
  10. John E.

    John E. TPF Noob!

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    I do the same as ksmattfish and only use the centre point for focusing. I mostly shoot stills, I realize weddings are a whole different ball game . I use the spot metering first and take a reading then I center the AF point on an edge that I want to focus on and quickly switch the AF to manual being careful not to move the zoom, I find I get a better success rate this way. I also like to choose the point of focus on landscapes also, I never did trust computers Glad to hear I am not the only one with AF issues . I use the sigma 18-125mm lense. What I wouldn't do for an old fashioned split screen
     
  11. ksmattfish

    ksmattfish Now 100% DC - not as cool as I once was, but still

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    See the posts above. I love my split screen in my 20D. :)

    I use the custom function that makes it so the shutter release button is the meter lock, and the AF is switched to a button on the rear of the body. Not that I really ever use the AF anymore.
     
  12. John E.

    John E. TPF Noob!

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    Thank you so much ksmattfish, it is now on my must have list. :thumbup: :D
     

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