Canon EOS Extension Tubes

[cspratt]

I can purchase (used) a set of three Canon EOS extension tubes (13, 21 and 31mm) for almost the same used price as a Canon 25mm tube by itself. Apart from the obvious size differences and having 3 tubes, is the 25mm a better buy?
Are there some operational differences I should look for? I will be using them (or it) with my Canon 10D and Canon 10s.

[Jon]

The combination will give you more flexibility in magnification. Do they support AF as well as aperture control? Some don't.

[DavidEB]

either get the combination, or, if it's cheaper, get the 3-tube kenko set. I can't see any reason to get the canon tubes over the kenko ones.

[bolantej]

they are tubes with (sometimes) connections to maintain aperture/AF control. the brand makes no difference. I would get the Kenko set (I have it) if it's cheaper than the whole canon set you are being offered. You may want the extra length later on, you never know.

[Wilt]

As suggested, get AUTO extension tubes (regardless of brand) if you can, to preserve focus and diaphram control.

[ScottE]

Be aware that Canon fills their tubes with genuine Japanese air in the centre while the others are made with Taiwanese air, and some brands even use Singapore air. If you are lucky you might find a vacuum packed model that you can fill yourself with crystal clear Rocky Mountain Canadian air.

[jaysmith]

As the other replies suggest, beware of a lot of extension tubes labelled suitable for canon EOS are simply a set of screw-in metal tubes with an adapter at each end - they should NOT be labelled auto (often are) and have no autofocus or control over aperture.