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Old Dec 14, 2011, 8:15 PM   #1
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Default Can I mount an old telephoto lens on a 40D

I have an old 400mm telephoto lens with a T-mount. My son has a Canon 40D and I thought I would give him the lens if it would work. Will an old telephoto lens (circa 1968) work on a Canon 40D?
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Old Dec 15, 2011, 5:36 AM   #2
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There are T-Mount adapters for the Canon EF mount on your son's 40D, so he could use your lens with an appropriate adapter.

But the T-Mount only provides a mechanical connection between a camera and a lens, not an electrical one. The lens will not autofocus, nor will it support any of the D40's autoexposure modes.
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Old Dec 15, 2011, 6:06 AM   #3
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Thanks for the info. I was told that the lens would not focus with the Canon. Will focusing be a problem and if so can it be solved?
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Old Dec 15, 2011, 6:59 AM   #4
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Modern dSLRs don't have the same focusing screens that helped get precise focus on earlier manual focus film SLRs, so manual focus tends to be less accurate than autofocus, especially for moving subjects.

But an AF Confirm T-mount Adapter will at least allow the camera's AF system to detect when the subject is in focus as the focus ring is rotated, and the AF point(s) will flash.
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