Focussing using an Extension Tube - HELP

[pjhpix]

Canon 50D with EF-S 17-85 lens.
To do some close up photography I recently purchased a Canon EF25 II Extension Tube to use in conjunction with the above.
However, when it is mounted with the lens I cannot achieve focus on anything, at any distance, at any focal length !!
I have tried focussing Manually, as well as AF ( and even switched off Image Stabilization in desperation).
I'm sure the lens and extension tube are correctly mounted.
AM I MISSING SOMETHING HERE ?
Any advice would be appreciated as I'm tearing out what little hair I have left over this Thanks

[raymon]

Re: Focussing using an Extension Tube - HELP

Sorry can't help but glad you raised this I was thinking of buying ex tubes in the near future, hope someone can be more helpful.


Ray

[X-ray-spex]

Re: Focussing using an Extension Tube - HELP

Is the lens compatable? Read somewhere that it doesn't work under 30mm ?

[Muscat]

Re: Focussing using an Extension Tube - HELP

No idea what is happening looking at this link it would seem that the lens should work http://www.usa.canon.com/app/pdf/lens/EFLensChart.pdf may be a daft suggestion but have you tried cleaning the contacts and trying again

[pjhpix]

Re: Focussing using an Extension Tube - HELP

Thank you for your replies. I've put the topic in the Macro Photography section and got some interesting advice there if you want to check it out (its probably the correct place for this thread) PJH