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Thread: How Do You Test a New Lens?

  1. #61
    Super Moderator Kayaker72's Avatar
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    Quote Originally Posted by neuroanatomist View Post
    I don't know, Brant. That flag looks awfully blurry… Are you sure it's not a decentered element?
    How'd I miss that!!!

    Quote Originally Posted by HDNitehawk View Post
    I think it is a Image Stabilization problem. I would keep the lens and if it bothers him he can send it to Canon and tell them the IS isn't working.
    And it doesn't even have an IS ON/OFF switch.....what is this, an EF-M lens???

    It's going back....

  2. #62
    Quote Originally Posted by Kayaker72 View Post
    For those interested, after testing NINE copies, my odyssey with the 24-70 II appears to be over.
    A couple of years ago I had the worst luck with a Tamron 70-300, and went through 4 copies before giving up. I thought that was bad! It's NOTHING like the problems Kayaker72! I though 4 copies was crazy bad - Chinese QA and all that. But a $2200 lens?!?!

    The luck you had, holy smokes! I had heard about the 24-70/2.8L II "clicking" and was afraid that I'd get it. Especially since I'd heard some people were being told this was normal and that they were settling for it. My copy - the very first one was brilliant!

    Whew!

    So, I've been lucky. When I bought my kit 6D, the first 24-105 was awful. Just really soft. I had gotten advice to just MFA the thing, but I figured if it was that far off spec, why? Of course copy #2 was great. My 24-70 is sharper than the 24-105 everywhere, at every aperture. But, it does take a little bit of pixel peeping, and the lens has fooled me more than once - which is good if I need to refer to the EXIF data for just a second!

    Anyway, I do all kinds of things when I'm testing a new lens - but mostly I just shoot. Back when I was on my 60D, I was stuck with the inability to do any sort of adjusting. I was even more paranoid and went through a battery of tests quickly to be sure I had a sharp lens. If I suspect there's an issue I'll perform certain tests on it. The ones I do the most are tests for front/back focus or decentering. I'll shoot the battery/box test to verify I've got front or back focus either close or at distance. If it was consistent I'd shoot a linear chart to see the exact distance I was dealing with.

    Now that I've got the 6D, I picked up the FoCal program. I actually took the vector PDF chart and made a much larger printout, which is helpful with UWA's or shooting at distance.

    For suspected decentering issues - or just to check corner sharpness - it's hard to beat a brick wall! So, when I got my 16-35/4L IS, I just started shooting, and did a bunch of comparisons between all my zoom lenses. It really is interesting to do, as there's a lot of differences besides sharpness. How they handle blown out areas, dark areas, color differences etc. The 16-35 is looking to be one of the sharpest lenses I've got. However - I saw that Roger Cicala had mentioned that he was seeing a "tilting" (maybe) with the 16-35. The ONE test I hadn't done was putting it on a tripod dead level, and shooting a wall square on. Of course, if you think you perceive a soft corner or side, rotate the camera to make sure you're not just out of square.

    So - I took my 17-40 and 16-35 to the high-school's brick wall. Bottom line - it's sharp, it's square, it's a fantastic lens! I'm keeping it! Images are straight from RAW jpeg, no PP of course. These are reduced images - anyone who's crazy enough to want to see the full sized image, just go to the URL and remove the "sm" from the address. Below are both ends of the range of each lens at f4, along with a 1:1 clipping (800x533) of the bottom right corner. All the corners on each lens appear to be the same as far as sharpness - and the linear quality of each lens is pretty consistent too as you can see. Don't need to worry about the tilt that Roger saw on his copies. I can hardly wait for the Adobe lens profile to come out for the 16-35!

    16-35 @ 16, f4


    Bottom right corner 100% 1:1


    16-35 @ 35, f4


    Bottom right corner 100% 1:1


    17-40 @ 17, f4


    Bottom right corner 100% 1:1


    17-40 @ 40, f4


    Bottom right corner 100% 1:1


    All in all - the 17-40 is still a great lens, and quite sharp in the center. Of course it improves greatly at 5.6 and is very good at 8 - but the corners are certainly a weak spot. Not so the 16-35. It's very comparable to the 24-70/2.8L II in the corners. Looks like I'll be selling my 17-40 before I've even had it for a year!
    Last edited by Anthony M; 07-21-2014 at 04:58 AM.

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