Another DSLR lens with focus issues

Discussion in 'Digital Photography' started by RichA, Sep 3, 2013.

  1. RichA

    RichA Guest

    RichA, Sep 3, 2013
    #1
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  2. RichA

    Guest Guest

    Guest, Sep 3, 2013
    #2
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  3. RichA

    otter Guest

    The low contrast test they chose is tough for any PDAF system to focus
    on. It's made tougher by the thin DOF at f/1.8. I'd like to see a
    comparison to how well the Canon EF 50mm f/1.8 does with the same camera
    & target before I'd condemn Sigma.
     
    otter, Sep 3, 2013
    #3
  4. RichA

    J. Clarke Guest

    Canon won't give up the specs. This is long established.
     
    J. Clarke, Sep 3, 2013
    #4
  5. RichA

    Sandman Guest

    Canon won't give up the specs. This is long established.[/QUOTE]

    Wait, what? Is this true? Does Canon not share the specification of
    their autofocus to other lens manufacturers?

    Does Nikon? I mean, my Sigma 28/1.8 is one of the sharpest lenses I own.
     
    Sandman, Sep 3, 2013
    #5
  6. RichA

    Sandman Guest

    Can't comment on Sigma as a whole but my Sigma 28/1.8 is one of the
    sharpest lenses I own. My 150-500 isn't very sharp, though.
     
    Sandman, Sep 3, 2013
    #6
  7. RichA

    Sandman Guest

    It's a shame they didn't try it with Nikon to see if there was a
    difference.

    Either way, this lens is compatible with their USB dock for focus
    calibration of the lens, so if there is a problem, it should be able to
    fix it.
     
    Sandman, Sep 3, 2013
    #7
  8. RichA

    Guest Guest

    it's true. all the lens companies reverse engineer the protocols, which
    is why there are occasional glitches.

    sigma reuses rom chips, so some lenses misidentify themselves.

    sigma goes even further and uses canon's protocol for their own sigma
    mount lenses (for sigma cameras), which has a pentax mount plate (with
    very minor tweaks). they also copied nikon's stabilization design and
    got sued.
     
    Guest, Sep 4, 2013
    #8
  9. RichA

    Nick Fotis Guest

    As far as I know, only Sigma decided to reverse-engineer the EF lens
    protocol instead of paying Canon for a license. This has resulted in
    many old lenses having to be sent back to the factory for re-chipping
    after a change in EF protocol happened during the EOS 5 film camera body
    (I was a victim of this as well)

    Other companies like Tokina paid for a license, as far as I know, so
    there were no compatibility problems.

    N.F.
     
    Nick Fotis, Sep 4, 2013
    #9
  10. RichA

    Guest Guest

    no they didn't. tokina reverse engineers the protocols just like
    everyone else and has the occasional compatibility issue, just not as
    many because they do a much, much better job than sigma does.
     
    Guest, Sep 4, 2013
    #10
  11. RichA

    J. Clarke Guest

    According to Chuck Westfall at Canon USA, Canon has never licensed their
    mount to any other manufacturer.
     
    J. Clarke, Sep 4, 2013
    #11
  12. RichA

    Guest Guest

    tokina was started by ex-nikon people and was founded before there were
    autofocus lenses with signaling protocols, so there was no information
    to take with them (not that they legally could).
     
    Guest, Sep 5, 2013
    #12
  13. RichA

    Nick Fotis Guest

    That's interesting to hear.

    Probably Sigma just made a less successful reverse-engineering effort on
    the EF mount protocol then.
    Anyway, I avoid their lenses as much as possible after my experience
    with them.

    N.F.
     
    Nick Fotis, Sep 5, 2013
    #13
  14. RichA

    J. Clarke Guest

    Their flashes don't do much better. They work reliably but the ETTL
    remote features are badly broken--they don't even work when both flashes
    are Sigma.

    Something's wrong in their engineering department when their own stuff
    doesn't work together.
     
    J. Clarke, Sep 5, 2013
    #14
  15. RichA

    PAS Guest

    Late to the party on this thread but what third party lens manufacturer has
    a license from any OEM for lens protocols?
     
    PAS, Oct 16, 2013
    #15
  16. RichA

    PAS Guest

    Nikon's lawsuit against Sigma was dismissed.
     
    PAS, Oct 16, 2013
    #16
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