Canon EF 100-300 1:5.6 with extension tubes?

[Wizmatt]

Hi all,

I am looking at using an old canon EF 100-300mm lens with extension tubes. I was wondering due to the age of the lens (over 20 years) if it may have problems when fitted with extension tubes. I am looking at Kenko autofocus tubes and am worried that the lens will not allow me to set aperture or autofocus etc. If anyone has any experience with this I would appreciate hearing it. Many thanks.

[djeyewater]

Hi Wizmat

As far as I'm aware, if the lens works on your EOS camera, it should work with the modern Kenko (or Canon) extension tubes. I can't guarantee that it would work, but I would be quite surprised if a lens worked on a camera but not with the modern Kenko or Canon extension tubes.

However, you're unlikely to get autofocus when using the extension tubes with that lens, as the majority of Canon cameras only autofocus with f/5.6 (and faster) lenses. When you attach the extension tube, you will loose light and the effective aperture will be less (e.g. f/8, though it depends on how much extension you use).

I know there are lots of third party (normally cheap chinese) extension tubes that don't pass information from the lens to the camera. I'm not sure if Kenko used to make extension tubes like that, but I'd check the description of the ones you're looking to purchase just to be sure.

Dave

[slimrbp]

Hi wizmatt,

I agree with Dave I can't see any reason why they wouldn't work.

Autofocus will still function even with a f5.6 lens, adding an extension tube does reduce the amount of light hitting the sensor but doesn't change the effective aperture, so even with the 'clever' extension tubes the camera will not know it's there and the ETTL system will compensate, although you may find it hunts more in low light.

Just to confirm this I put a 31mm extension tube on my EF-S 55-250 and the autofocus worked fine.

Cheers,

[Wizmatt]

Thanks for the feedback. I've found some in a store in town so I'll try them out.

Thanks.