Measurbating the Sigma 30/1.4

Discussion in 'Lens Lust' started by GroovyGeek, Sep 13, 2008.

  1. OK, so I usually don't spend (a lot of) time measurbating, but with Sigma lenses you kinda have to do it, because you never know what you are going to get :biggrin:.

    I recently purchased a Sigma 30/1.4 for my D40. While you don't buy a lens like that for sharpness, my copy seems to drop off rather sharply below f/2.8. The whole purpose of this lens is to use it down there, so I am wondering... What do Sigma 30 owners think --- par for the course or send to New York for tweaking? I don't want to play the Sigma lottery and exchange for a different copy.

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    Last edited by a moderator: Sep 13, 2008
  2. evokel

    evokel

    326
    Sep 6, 2008
    florida
  3. Nuteshack

    Nuteshack Guest

    got one for my wife's d40 ..it's SHARP at 1.4...if u have any doubts by all means send it in....;-)
     
  4. Indeed. It does appear that you have a bad copy there, did you do the test shots with a tripod? It does look like you have.
    If not I would recommend doing so before sending it in.
    I had the same lens but for Canon, it was very usable at f/1.4 if you were steady and precise.
    T.
     
  5. All shots were on a tripod with a wireless trigger
     
  6. Confirmed.
    Send it in mate. The results should be so much better.
     
  7. mycom

    mycom

    67
    Apr 24, 2006
    Don't confuse sharpness with contrast ! I think even at f1.4 your copy seems sharp to me - howver the contrast is lower - which is expected !
     
  8. weiran

    weiran

    966
    Jan 2, 2007
    Nottingham, UK
    mycom is right, it looks perfectly sharp at f/1.4, but with a lack of contrast. I'm not sure what you're expecting, but it's impossible to make a lens that's as sharp at f/1.4 as it is at f/8.

    To test the lens better, try taking a shot of something like textured paper so you can really see the resolution rather than contrast.
     
  9. mycom

    mycom

    67
    Apr 24, 2006
    There is an ever so slightly backfocus -assuming you had the cam focus at the red line - but that need to be verified with other lenses - could be the cam as well.

    Have a look at tests of the 85/1.4 - you will also see a tad lower contrast until you reach 2.0.

    My 30/1.4 behaves excatly the same why as does my 50/1.4 and 50/1.2 and....
     
  10. Yes, I noticed the backfocus. It is the cam, it does it with the 70-200 also, it is particularly noticeable when shooting it wide-open with a somewhat distant object. I need to get around to tweaking it a bit some day, did it on my D70 several years ago.

    Will do. Thanks for the suggestion...