[Bill G]

Are there teleconverter available for Pentax dslr cameras,preferably by Pentax.

BG

[jatrax]

Only used ones at this time. And none of those are auto-focus. There are a few third party ones available as well, with screw drive auto focus, some also work (sort of) with SDM lenses.

There is a new TC on the Ricoh road map, but no idea when or if it will actually be produced.

[JimJohnson]

You are often better off to crop than use a teleconverter in the digital world. Unless the teleconverter is carefully matched to the lens, the softness and/or aberrations introduced by the extra glass elements will cause a greater loss of image quality than a simple crop. This is especially true if the final image will be used only for digital display or smaller print sizes (less than poster size).

[lister6520]

I have three teleconverters, two are old ones from the film days and one I bought recently that is auto and has autofocus but screw drive only. It does work but as JimJohnson said I found that by cropping I can get the same (or more) magnification as the teleconverter and still get a sharper image than the uncropped one with TC and you also don't lose two stops of aperture.

In the end I just took out the lenses form the teleconverters and use them as extension tubes instead.

I think for a teleconverter to actually produce a better magnified image than you can by cropping you would either have to have a rather low resolution camera, say 6MP or less, or else have a teleconverter that is designed for one specific lens and matched with it at the factory.