extension tubes

There is a set of kenco extension tubes on e-bay with a fitting stated as Pentax PK mount! any idea if these will fit the k20??

PK mount will fit the K20D.
However, it is easier if you can get extension tubes that include electrical contacts - that will keep the aperture information between lens and body.

If you get tubes without electrical contacts then you'll have to have a lens that has an aperture ring and you'll have to use stop-down metering.

Mine are Triplus and include the contacts
Matt

They are down as auto? this meens they have the contacts right???

Auto in the context of extension tubes means they convey the auto stop-down on lenses. This is a mechanical coupling and quite different to the electronic contacts that are desireable.

Don,
As John says, the "Auto" is the little "finger" that stops down the aperture when you are using it in the "A" mode on the lens. However, this is distinct from the electronic contacts - the majority of teleconverters do NOT have these contacts

It'll be more helpful if you can provide a link or an item number
The tell-tale sign is looking at the end where the lens mounts. If you see just plain silver metal - then it's not got the contacts. There should be 8 little "bobble" contacts around one side of the extension tube.

Matt