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DPChallenge Forums >> Hardware and Software >> Canon 20D + Extension Tubes help plz
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07/05/2005 12:22:13 AM · #1
I'm having problems getting things to come in clearly, even though through the eyepiece it looks crystal clear. Most of the times im forced to use manual focus b/c the auto focus wont work that well with the extension tubes on.

I am using a Canon 20D, with either Canon 75-300mm, Canon 28-105mm, or Tamron 19-35mm lenses and ProOptik extension tubes(13mm, 21mm, & 31mm).

Am I doing something wrong, or is it just that difficult to use. Or is it because of the cheapo extension tubes?
07/05/2005 12:26:50 AM · #2
When you add the extension tubes the DOF is going to shrink very quickly. You sometimes have to move slightly back and forth to get what you want in focus and yes it's best to use manual focus as the auto focus just hunts when the DOF is so shallow. I have the same problem with the Kenko extension tubes.
07/05/2005 12:32:38 AM · #3
Autofocus doesn't work with Pro Optic extension tubes (it's a mistake on Adorama's web site). According to "Fred" at Adorama, the ONLY extension tubes that work with autofocus are the two Kenko tubes sold individually (not the set) and Canon's own model. They'll be replacing my order as a result.

I get the best results using the Canon 28-105 (or other long lens) at full telephoto and manual focus. Use the smallest aperture possible under your lighting conditions and set the manual focus just shy of infinity, then move back and forth until your subject is in focus. Brace the camera any way you can because it doesn't take much movement to blur tiny details. The 20D gives you an advantage because you can use ISO800 and a smaller aperture to get more depth.

Message edited by author 2005-07-05 00:34:58.
07/05/2005 12:49:32 PM · #4
Ah good info.. And thanks.. I don't mind them being only manual focus. I feel that helps you strengthen you camera skills anyways. But making sure the auto focus was crazy because of that and not me, makes me feel better ;-)

Ill just have to play around with it alot.. Getting used to the lack of light hitting the sensor is another smack, heh. I guess really I need to find out what combination of ext tubes and lenses gives me a nice balance of focus and clarity with a great deal of magnification.

Thanks again..


07/05/2005 01:14:26 PM · #5
I used my 17-40 L F4 lens with the canon 25mm Extension tube on this macro challenge and I'm very happy with the result and score.. :-)

The focus is spot on with both manual and autofocus.

Regards - Tony

Message edited by author 2005-07-05 13:14:50.
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