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Author Topic: 24-70 & 70-200 = different versions of 70mm  (Read 1728 times)

Ryant

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24-70 & 70-200 = different versions of 70mm
« on: May 10, 2012, 01:32:47 PM »
I was testing my lenses out by shooting the same subject. An unsuspecting flower in my kitchen. I found that my 24-70mm and my 70-200mm do not match when both set to 70mm. Is this normal? Examples included.

Ryan

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24-70 & 70-200 = different versions of 70mm
« on: May 10, 2012, 01:32:47 PM »

Ryant

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Re: 24-70 & 70-200 = different versions of 70mm
« Reply #1 on: May 10, 2012, 01:33:39 PM »
BTW these with both shot on a tripod with a 5d mark iii.

imkev

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Re: 24-70 & 70-200 = different versions of 70mm
« Reply #2 on: May 10, 2012, 02:36:25 PM »
I just tried the same thing with a 5d2 and a 24-70 and a 70-200 2.8 mk II...I had the same results as you did. I tried the 70-200 mounted both ways, with lens tripod mount and with the camera mounted. They were both different than the 24-70...kinda hard to judge though because when using the camera mount the 70-200 is longer, but when using the lens mount, the camera is slightly higher...both could have caused the results we encountered...
5D2, 7D, T2i and way too many lenses.

Random Orbits

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Re: 24-70 & 70-200 = different versions of 70mm
« Reply #3 on: May 10, 2012, 03:12:14 PM »
Pretty normal.  The designed focal length of lens does not match what is printed on the lens/box exactly -- it is rounded.  If you look on this site, you'll see it on the patent applications (focal length and f stops).

Another factor is that zooms typically have different focal lengths based on how far the focus point is from the camera.  The closer the focal plane, the more focal length you lose.  Focal lengths are typically measured at focus at infinity.

Dart23

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Re: 24-70 & 70-200 = different versions of 70mm
« Reply #4 on: May 10, 2012, 03:15:48 PM »
Pretty normal.  The designed focal length of lens does not match what is printed on the lens/box exactly -- it is rounded.  If you look on this site, you'll see it on the patent applications (focal length and f stops).

True - The recent 70-300 DO patent showed an actual length of 72.50-290.90mm...

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Re: 24-70 & 70-200 = different versions of 70mm
« Reply #4 on: May 10, 2012, 03:15:48 PM »