Auto extension tubes making Canon 5D hunt for focus

[drb5]

Got my 5D just in, fitted with a 28-135mm. Stuck my old auto extension tube/s on it and it appears to hunt quite badly for focus.

I don't remember there being a problem before, but they're a good age now, the tubes.

Anyone had similar problems? Should the Kenko tubes be better? Still have it in the back of my mind, just getting a suitable macro lens...

 

[mikew]

Dont know what the 5D will focus down to but what F stop are you ending up with when using the tubes.

 

[ThomasH]

With macro getting enough usable light can be a issue. If there was not enough light especially if its relatively low contrast subject af will tend to hunt so it may just be that.

 

[Neil B]

With macro getting enough usable light can be a issue. If there was not enough light especially if its relatively low contrast subject af will tend to hunt so it may just be that.

and you will find manual focussing easier and more accurate when doing macro with tubes

 

[drb5]

F-stop was changed from 4.5 at the wide end and through to long end, trying up to f11.

Tried it inside and outside with good and bad light, with the same effect...almost no attempt to try and fix focus.

No big deal, just thought it was worth a try. Will go manual focus and keep an eye out for a 100mm f2.8 macro, or similar...

Thanks for the help chaps and best wishes.

 

[HoppyUK]

Got my 5D just in, fitted with a 28-135mm. Stuck my old auto extension tube/s on it and it appears to hunt quite badly for focus.

I don't remember there being a problem before, but they're a good age now, the tubes.

Anyone had similar problems? Should the Kenko tubes be better? Still have it in the back of my mind, just getting a suitable macro lens...

With extension tubes, you lose light. The effective aperture drops by two stops at 1:1. Canon's AF doesn't work with most cameras at f/numbers higher than f/5.6, and the tubes will take you well above that at 135mm.

 

[drb5]

Many thanks mate.