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Author Topic: Separate camera lens/body  (Read 2246 times)

nackmack

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Separate camera lens/body
« on: December 18, 2010, 04:57:30 pm »

Hi all. I have a Canon 7D camera and a Tamron 17-50mm lens. I am working on a project that requires me to separate the Tamron lens from the camera body by approximately 3 inches and still be able to capture in-focus photos.

My question is as follows: is there a way to focus the light coming out of the back of the separated lens so that the image produced by the Canon 7D is as in-focus as an image produced when the lens is attached normally to the camera?

Thanks for your help.
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wolfnowl

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Re: Separate camera lens/body
« Reply #1 on: December 19, 2010, 02:36:08 am »

Well, basically what you're talking about is an extension tube, which is a hollow collar that mounts between the back of the lens and the camera body.  However, by moving the lens away from the body (and 3" is about 76 mm), you're going to be changing the point of focus considerably - making your 'normal' lens into an extreme macro.

Without more information on the project, it's hard to be able to advise you on what you're trying to do.  If you want to move the lens 3" in front of the camera body and have it focus and operate normally, the answer is no.

Mike.
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JohnTodd

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Re: Separate camera lens/body
« Reply #2 on: December 19, 2010, 02:01:07 pm »

A couple of teleconverters together might add up to three inches and still allow infinity focus, but then you'll be limited to a very narrow field of view. As Mike says, more details, please! Sounds interesting.
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Rod.Klukas

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Re: Separate camera lens/body
« Reply #3 on: January 10, 2011, 11:33:45 am »

You will be manually focusing as the others mentioned.  However wide lenses are notorious for terrible lateral chromatic abberation.
So the quality from this method may be quite poor even if you can focus and get light on the subject.
A true macro lens, even the low priced 50mm 2.5, from Canon, would do a better job.
Just some comments.
Interested to hear what you are trying to do.

Thanks,
Rod
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aduke

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Re: Separate camera lens/body
« Reply #4 on: January 10, 2011, 02:19:23 pm »

I created at stack of Canon 40D, Canon extender ef 2x II, 36mm extension tube, 50mm lens and managed to achieve focus at about 3". DOF was quite small but not completely unusable.  You will need a lot of light :)

Alan

Edit: the length of the extender and extension tube is greater than 3.5".
« Last Edit: January 10, 2011, 03:56:00 pm by aduke »
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