question about angle of view on two 17-50mm lenses

Discussion in 'Photography Beginners' Forum' started by theregoesjb, Feb 11, 2012.

  1. theregoesjb

    theregoesjb TPF Noob!

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    I have been spending way too much time comparing two different lenses,

    Sigma 17-50mm f/2.8 (600$)
    Tamaron 17-50mm f/2.8.(400-450$ without VC).

    Its tough because although they get nearly identical reviews i have seen some terrible test images for the tamarons auto-focus, which makes me wonder if the sigma is worth the extra 150.00 (if you have any personal recommendation feel free to share)

    While comparing all their specs on B&H i noticed their "angles of view" are different:

    Sigma: 72.4° - 27.9°
    Tamaron: 78° - 31°

    what does this mean? how can they be different if they are both "17-50mm" ?


     
  2. 480sparky

    480sparky Chief Free Electron Relocator Supporting Member

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    Focal length is but one measurement of the optics. It does not always mean the same FOV.

    You're also speaking of two different manufacturers. One may measure from side to side of the image, the other may be corner to corner.
     
  3. enzodm

    enzodm No longer a newbie, moving up!

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    ... and often focal lengths are rounded to common values.

    However, I always found good reviews of the Tamron, which in fact will be sooner or later my upgrade for the kit lens. If you have to share a link to what you found, I'm glad to read it.
     
  4. theregoesjb

    theregoesjb TPF Noob!

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  5. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    I used the Tamron (non VC) for several years and it was a great lens. The AF was slower and louder than I would have liked (it's no Canon USM) but I never had an issue with AF accuracy like he's showing in that review.
     
  6. DiskoJoe

    DiskoJoe Been spending a lot of time on here!

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