So... how can I tell if the expensive lens I bought is a good copy?

Discussion in 'Digital Photography' started by Archibald, Mar 24, 2008.

  1. Archibald

    Archibald Guest

    People regularly report that there is variance in the performance of
    Sigma lenses. Canon lenses ALSO vary, and I'm sure Nikon does too...
    so the lens you buy might be a dud.

    I've even heard that some pros will buy 6 copies of a lens, like a
    500mm, test them, and then return 5, keeping the best one.

    How the heck can a person evaluate a new lens purchase to find out if
    it is a good copy, without having an optics lab... and objectively
    (without subjective guesswork)? Can ordinary folks do this, or do you
    have to be some kind of expert?

    Archibald, Mar 24, 2008
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  2. Here are methods I use, at,
    and why I do not use some other commonly used methods. As for
    variability of lenses in the Nikkor line, you may find this interesting: You may notice that more
    extreme lenses (wide range zooms, especially ones including WA, and
    wides that have "floating elements") lead in variability. Generally, long and
    fast (or expensive, slower, or shorter) teles vary the least among samples.
    I have seen huge variability in samples in some well known lines, but with
    a few exceptions, not much in the Nikkor line of lenses. BTW, trying
    to remove subjectivity from the process of lens evaluations is, I think,
    not the most useful way to go (at least after you have established that
    a lens is well aligned and up to *your* standards for edge/corner
    performance at the stops and shooting conditions of interest to you).
    There are no perfect lenses - so you choose from among a bunch
    of compromises what will best work for you. I buy from a good dealer
    that offers "painless" returns/exchanges, and I CHECK FOR DEFECTS
    IMMEDIATELY, while I can still do something about a poor sample
    beyond selling it on eBay. I'm still surprised when a pro shooter friend
    doesn't bother to do this, and then asks me something like, "Do the
    lower left corners of these prints shot with XYZ lens look soft to you?",
    usually about a year after the expensive purchase...
    David Ruether, Mar 24, 2008
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  3. In my opinion, there is only one important test. That is does it work
    for you. Try it under the conditions you plan to use it. If that means
    photos of a football game, you don't want to test it by photographing your
    son on the other side of the living room.

    Frankly I was a professional photographer for about 8 years, quite a
    long time ago. Someone who would but 6 copies of a lens and return five
    would have been laughed at. What was most important to us was durability
    and reliability.

    Honestly, make sure it fits your needs. Knowing it fits my needs will
    not help you much. I would test it under the conditions I would have bought
    it for. When I do get a new lens, that is exactly what I do. I have only
    had one example that I was less than very happy with, and it was OK.
    Joseph Meehan, Mar 24, 2008
  4. Archibald

    Frank Arthur Guest

    That's known as an Urban Legend. Realistically no one buys $50,000
    worth of 6 lenses
    including big two way shipping charges- even if the supplier would
    take back the 5 unpacked beand new lenses.

    When you take home the lens and try it out under the conditions you
    normally shoot with.
    Try different f stops. Also try some shots using your camera on a
    tripod or stand to eliminate lens problems that appear as camera
    Examine the images closely. If there are no significant visual
    problems with the results like partially blurred images, out of focus
    corners or edges or any unusually poor results return the lens.
    I almost always buy Nikon lenses and find it extremely, extremely rare
    that a lens I bought was not good.
    Frank Arthur, Mar 24, 2008
  5. Hi folks.

    I thought a Sigma telezoom was good until :
    - the first one wouldn't stop down from full aperture and
    - the second one shed a screw head from its mount into my camera body.

    This was years ago but then
    - a Sigma 105mm macro was noisy and slow to focus and it was too easy to
    catch the focussing ring and put it into Manual Mode while the lens's
    focussing switch was in Auto Mode.

    I also had a Vivitar (there's a name from the past) macro lens that was
    outperformed in terms of sharpness by my Canon 70-210 zoom.

    I now routinely check new lenses for sharpness across the range of apertures
    and focussing distances. I'm not too concerned about absolute performance,
    all I want is sufficient sharpness and lack of distortion for me to enjoy
    viewing my photos.

    Regards, Ian.
    Fred Anonymous, Mar 24, 2008
  6. Archibald

    RichA Guest

    Depends on the lens. You'll pay $1000+ for an old Olympus 18mm f3.5
    but wide open, it likely will look worse than a good, current digital
    lens of the same effective focal length. If you have a decent normal
    lens, that you know is good, you could compare it against it.
    Download and print a resolution chart and take some images, wide open,
    stopped down, etc.
    RichA, Mar 24, 2008
  7. I would agree that would be some good advice if Archibald was interested
    in photographing resolution charts, but if he is interested in photographing
    his son on the football field moving and if that is a stabilizing lens, he
    is not going to get much useful information from a photo of a static chart a
    few feet away from his lens.

    Rich, try to say this every morning for the next week. "Photography is
    an art where the artist uses tools. The art created is a result of the
    artistic ability of the artist, not the tools he uses." I know this is
    true because I bought a set of "Pablo Picasso's brushes on the internet and
    I could not do as well as he did with those brushes.
    Joseph Meehan, Mar 24, 2008
  8. Archibald

    Frank Arthur Guest

    Probably because you didn't buy Pablo Picasso's paints & Pablo
    Picasso's Canvas and the Pablo Picasso instruction book..

    Frank Arthur, Mar 24, 2008
  9. Yeah, I bought one 500/4L IS USM and I really got a winner on my first try!
    I ended up selling the piece of shit and got the Nikkor version for $2K
    Just buy Nikon lenses.

    Rita Berkowitz, Mar 24, 2008
  10. Archibald

    Rich Guest

    I see idiot Rockwell has brainwashed you too.
    Rich, Mar 25, 2008
  11. He should have never strayed from his predetermined path in the first place.

    Rita Berkowitz, Mar 25, 2008
  12. Archibald

    Archibald Guest

    Thanks, David.

    You have obviously thought about the subject, and I appreciate you
    sharing with us what you learned.

    Archibald, Mar 25, 2008
  13. ["Followup-To:" header set to]
    Note to OP: Rita's religion is that Nikon's shit doesn't stink,
    Canon is the arch-enemy, and facts don't matter. Rita has not
    yet learned to practise religion in private, or at least in

    Wolfgang Weisselberg, Mar 25, 2008
  14. Archibald

    Anonymous Guest

    Anonymous, Mar 27, 2008
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