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Sigma 30/1.4... testing for sample variation

Discussion in 'Lens Lust' started by Holmes, May 15, 2007.

  1. Holmes

    Holmes

    Oct 28, 2006
    Wyoming, USA
    Greetings,

    Couldn't find one of these elusive little lenses through a more mainstream distributor so I finally ordered from a Hong Kong eBay outlet - $450 delivered - ouch! The cost of impatience :rolleyes: 

    Been shooting it for a week or so on a D200 and D40. Pretty happy with it but some images seemed soft. Given all the talk about sample variation and AF accuracy with this optic, I decided to run it through the typical testing procedures.

    Firstly, I set up the simple flat text target, squared/leveled the tripod to the target, and activated autofocus. Switched to manual focus and took the shot. Next, I moved the target carefully .5cm forward and back taking a shot at each position.

    Now it was time for the 45 degree AF tests that Len Shepherd is so fond of! I tend to agree with him about these tests as they are so error prone. I did the test twice, once with the target angled and once with the camera angled. I was careful to keep the sensor outline incorporating about half of the target line.

    Off to the 'puter with the cards (SD and CF). All testing was done sans in-camera processing. Opened with NX, autolevels, saved as tiff. Opened in CS2 and smart sharpened (Rockwell's settings).

    Upon viewing the images at 100% it was quite clear that this lens was performing with an amazing level of precision. Absolutely no front or back focus and no problem with resolution.

    It seems the only problem this lens had was the twit behind the viewfinder! I simply didn't have enough time under my belt with the shallow DOF and target selection to get the most out of the Sigma, especially with regard to small distant targets.

    Embarrassingly, I had already called Sigma USA and they agreed to look at it and see what they could do even though the lens is a grey market version. Kudos to them! Now I have to call Tom back tomorrow and sing praise to the lens and confess premature paranoia on my part :redface:

    Methinks there is more sample variation amongst shutterbugs than there is amongst modern optics!

    Regards to all.
     
  2. Good to hear. I have this lens and love it! :biggrin:
     
  3. Latens

    Latens

    77
    Oct 18, 2006
    Taken a few pictures for another thread.

    http://www.pbase.com/paulorbaptista/sigma_test

    Altough the sigma is usually my choice for low light situations I was curious to find out how it performed in bright light.

    The gallery shows first the hole resampled image and after 100% details from center and corner.

    It won't replace the 18/200VR but really convinced me.

    Best regards,

    Paulo
     
  4. Holmes

    Holmes

    Oct 28, 2006
    Wyoming, USA
    Thank you, Paulo. Informative series.

    I'll be playing with mine in contrasty light this weekend. Looking forward to the exercise.
     
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