How to test new lens?

Discussion in 'Native Lenses' started by ajamils, Jan 25, 2013.

  1. ajamils

    ajamils Mu-43 Veteran

    Nov 20, 2012
    Richmond, Texas
    Lately, I have been reading a lot people complaining about receiving "bad copy" of lenses that are not sharp. In my past 5 years of shooting m4/3 I have never thought about this when I bought a new lens. I always used it without any testing and never found any issue (maybe because i wasn't looking for it).

    So my question is, how do you guys generally test (real world test) a new lens to make sure it is a good copy?
  2. Fmrvette

    Fmrvette This Space For Rent

    May 26, 2012
    Detroit, Michigan
    Real Name:
    Well, this is fast, cheap and easy:

    Checking Your Camera for Front Focus or Back Focus. | Camera Light & Lens Forum – News

    I generally will photograph the electrical meter on the side of the house - there are some very small teeth on the drive gears that are visible through the glass, and some very small letters on the case. If they all come in sharp, I'm good to go.

    However I have to admit...I don't test a lens unless I suspect there's an issue (I had a Tamron 18-55 on my D300 that was supposed to be very sharp, but I couldn't dial it in. Tamron service was excellent, problem resolved.)

    If the image looks good on an 8x10 print, it's close enough for government work :biggrin:.



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  3. addieleman

    addieleman Mu-43 All-Pro

    Aug 5, 2010
    The Netherlands
    Real Name:
    These front and back focus issues are mainly applicable to DSLRs, I had a hard time with my D200 and D300s for instance. Mirrorless cameras use contrast AF which is much less susceptible to this kind of thing. I tested my G1 with some lenses at the time, no problem at all.

    While focus accuracy of the camera is a good thing to check, it's more relevant to check the lens for sharp images. When I have a new lens (which happens very often, collecting Minolta lenses), I take it outside and take pictures of some trees against the sky as a first test. The branches against the sky tell you a lot about centre and corner sharpness, color fringes (coloured edges of branches) and general contrast. Sharpness evaluation is done at 100 % viewing, the best lenses still are sharp examined that way. If you deem it important, also take a picture of something with straight lines to see if the lens doesn't distort. Distortion means that straight lines are shown as curved lines in the picture. For distortion and general contrast you just view the entire picture at once, 100 % viewing is not applicable here.

    Lens testing is an extremely complex subject and I'm certainly not the expert in this. However, most of us want to know if a lens will perform satisfactorily and for that some real world testing is good enough. Take pictures as you would normally do and examine them carefully, meaning also at 100 % viewing. I know a lot of people scorn upon this as "pixel peeping", but IMHO it's the only way to really know what a lens is up to on your camera and how a large print would turn out if you wanted one.

    And yes, it is all too common to find uneven performance across the image. Yesterday I returned a Sony E 55-210mm after finding out that the lower edge and corners were distinctly unsharper than the rest of the image. One of my Panny 45-200mm samples was slightly unsharp at the right edge, etc. etc.
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  4. aimawayfromface

    aimawayfromface Mu-43 Rookie

    Jan 19, 2012
    I wouldn't worry about testing a lens beyond taking a few snapshots and making sure it's not defective (autofocus, zoom ring, focus ring, switches, etc.) and not too scratched up or dusty in the case of a used purchase.

    Unless you really need a perfect copy--and 99.999% of us don't--it leads down a deep dark path that ends up with you wasting a lot of time taking pics of test patterns, obsessively pixel peeping, stressing over whether to return a perfectly good but not astoundingly great copy, being nagged by the feeling that your IQ (photos and otherwise) is suffering from slight decentering, etc.

    Yes I speak from experience; it's not worth it. Forget about all the testing and just enjoy using it!