MF in AF Mode

Discussion in 'Photography Beginners' Forum' started by z.peletz, Feb 21, 2008.

  1. z.peletz

    z.peletz TPF Noob!

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    Is it ok the manually focus a lens while in auto focus mode? Or could this damage the motors?
     
  2. brileyphotog

    brileyphotog TPF Noob!

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    It depends on the lens. Also, is your lens self-driven or does the camera do it? Some lenses have a manual focus override and some don't. If you can grab the lens in autofocus and move it easily I'm assuming you've got a a lens with override.

    I guess I don't really understand your question. Do you mean manually focus with the lens set to M and the body set to A?
     
  3. z.peletz

    z.peletz TPF Noob!

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    I've got a 40D with the EF 28-135 IS USM. The setting is on the lens and it is pretty easy to move.
     
  4. MarcusM

    MarcusM TPF Noob!

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    I was just wondering the same question myself. I got my new 50mm f/1.4 USM today and was testing it out and found myself accidentally using the focus ring while it was on AF...anyone know if this is bad for it?
     
  5. brileyphotog

    brileyphotog TPF Noob!

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    The 28-135 does have manual focus override.

    Lucky.

    As far as the 50mm f/1.4 goes...don't y'all ever read your manuals?
     
  6. MarcusM

    MarcusM TPF Noob!

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    As a matter of fact, I did read the "manual" that came with it (which consisted of a large one-page piece of paper with about 20% of that paper devoted to English).

    It says "Do not touch the focusing ring on the lens during autofocusing"

    However, it does not say WHY to not do this, which is why I asked. It doesn't say if the reason is that it will damage the motor or if the reason is because you will lose the focus of your current shot.

    There is a section called "Full-Time Manual Focusing" which is what I think you were referring to about the override.

    But it still does not say anywhere whether or not turning the focus ring in AF mode will damage the lens, which is what both of us were wondering.
     
  7. bhop

    bhop No longer a newbie, moving up!

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    I'm pretty sure you'd damage the camera. My d70 won't even let the focus ring turn unless i have it set to MF.

    If you've got a camera with an internal focus motor, take off the lens and look at the body's mount. You'll see a little piece sticking out near the bottom (at least on my nikon) that looks kind of like the tip of a flathead screwdriver. That's what's focusing your lens. When an AF lens is attached to a camera that little thing is stuck inside the lens. When you switch it to MF mode, it goes inside the camera body so you can freely turn the focus ring without damage. You can see it go in and out if move the MF/AF switch with a lens off. (it won't hurt anything)
     
  8. brileyphotog

    brileyphotog TPF Noob!

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    It is not the body of the camera that matters, it is the lens. Some lenses have manual focus override and others do not.

    Marcus M...I googled "canon 50mm f/1.4 manual focus override" and found out that your lens also has this feature. The reason it says not to touch it during autofocusing is that if the servo motors are running and you grab the focus lens you'll burn the motors up. Once the lens has stopped, though, you should be able to manually focus without damaging the camera, even if AF mode.

    I didn't realize the Canon lens manuals were that bad. Sorry bro.
     
  9. Atropine

    Atropine TPF Noob!

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    The 17-55 f2,8 and the 70-200 f4 L I am using both allows manual focusing whenever I like in AF mode. I guess it differs from lens to lens. It's a really great feature and every lens should be built that way but I guess it all is a matter of cost.
     
  10. MarcusM

    MarcusM TPF Noob!

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    That makes sense, whew, what a relief! Thanks.
     

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