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Thread: How Do You Test a New Lens?

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    Super Moderator Kayaker72's Avatar
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    How Do You Test a New Lens?

    In rereading Bryan's review of the 24-70 f/2.8 II, I was reminded that he actually had issues and returned a couple of copies of the 24-70 II. This helped me recall that Rick also sent a few versions back after testing.

    What is the best way to test a new lens? I do own a copy of Reikan FoCal, which is what I believe Rick used. I've only used it to set my AFMA. I certainly want to make sure I get a good copy.

    Thanks in advance.

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    Senior Member neuroanatomist's Avatar
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    Assuming you have the Pro version of FoCal, run the new lens through the focus accuracy and aperture sharpness tests (Reikan has aggregated data from the latter on their website). Check that the vignetting is symmetrical (easy test for a decentered element).

    If you want to do the full monty, check out Roger Cicala's article on How to Test a Lens.

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    One of these days I should invest in FoCal. I just haven't been dissatisfied with any lens enough to push me to buy the software. For a quick test I line up three water bottles along the countertop in my office and shoot them (tripod mounted) from 15ft or so at an angle. I focus on the center bottle, of course, and see where the sharpest area is in relation to my focus point. On the 7D I made a few AFMA corrections this way. I haven't had a need to do so on my 6D yet.
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    Brant, John covered it. I printed off several decent charts to test against.

    I had all of my other lenses to test against also. For instance there is quit a bit of information and testing comparisons of the 70-200mm II at 70mm vs the 24-70mm II. I also had the 24mm L and 35mm L to test against. If you have similar lenses to test against I think it helps.

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    Super Moderator Kayaker72's Avatar
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    Rick and John....Thanks for the input.

    I received mine on Friday. I put it through some paces over the weekend. Almost everything checks out. Focus consistency was 24 mm 92.3% (a little low?), 50 mm 96.9%, and 70 mm 97.4%. The Aperture Sharpness test resulted in about the profiles I expected. Typically a very slight dip to f/2.8 from f/3.5. Very consistent from f/3.5 to f/8 (usually one spike ~f/4 to f/4.5) and then nearly linear decline. This is a little different than the "beta" average shown on Reikan's webpage for the 5DIII and 24-70 II. Theirs is pretty flat from the DLA to f/2.8. my f/8 through f/2.8 was ~7-10% higher than DLA). AFMA was +1 and +3.

    There seemed to be an ever so slight off centered nature to the vignetting, but Bryan's test charge appears to also have it, so I was going to say it was ok.

    But...when adjusting the focal length, there is a very audible clicking. Just saw a thread on CR, and apparently, this is a common problem. Apparently another poster was informed that it would go away as the lens was "broken in." But it sounds like either metal being compressed and released quickly or a gear tooth slipping.

    Anyone think this shouldn't go back? Right now I am taking it into work with the plans of exchanging it.

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    Brant, I checked mine at the mid range as well (35mm and 50mm). Almost every copy I found it to vary from the short and long end. Most copies stayed close to the 24mm setting through 50mm, then would have a shift at 70mm.
    IMO and experience accuracy on the wide end is always bit less on all lenses. But in real life this isn't going to be noticed. You have such a wide DOF at 24mm. I think it is important to know what it is doing at 35mm and 50mm as well.

    As with all test, I wash rinse and repeat to make sure I get the same results again. I like to see consistent results every time. If you were a bit off in your testing a second test usually highlights this for you.

    I have not heard any clicking in any copy I have. The zoom ring is a bit stiff and not the smoothest but no noise. The focus ring is very smooth and no noise. I am not sure I would like this.

    My opinion is this lens shouldn't have to be "broke in", that is just silly. It is a precision device and should work great out of the box. I am not sure I would keep the lens as this would bug me and it just doesn't sound right.

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    Senior Member neuroanatomist's Avatar
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    Quote Originally Posted by HDNitehawk View Post
    My opinion is this lens shouldn't have to be "broke in", that is just silly. It is a precision device and should work great out of the box. I am not sure I would keep the lens as this would bug me and it just doesn't sound right.
    Agreed - I would exchange the lens, unfortunately. My copy is also silent when zooming, except for the normal 'swoosh' sound that all zoom lenses make. That's consistent with the CR thread, where 2012 copies of the lens don't seem to have the click-zoom issue.

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    Brant, if you do send it back I would save copies of any tests you did with Reikan. The aperture sharpness test will come in handy for the next copy.

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    Super Moderator Kayaker72's Avatar
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    As usual, good advice. Thank you.

    A little tidbit, Adorama would like me to contact Canon regarding the issue. They didn't say they wouldn't exchange, but they didn't say they would either (edit...rereading the email, a couple of sentences after they asked that I call Canon, they did mention I could return the lens). I've already emailed back letting them know that I'll contact Canon, but asking if they would exchange it if the issue remains unresolved. No response yet.

    I'll wait and see how they respond and how this works out before making any judgement. But, it is a very different initial response compared to taking an item back with no questions asked that I've experienced with either B&H or Amazon.
    Last edited by Kayaker72; 10-22-2013 at 06:07 PM.

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    That is a bit odd. I would be disappointed if Adorama didn't do an exchange.
    A new item like that I usually tell the store "You call Canon and give me a different copy"

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