[zumbido]

Yes, Pentax and Nikon has kept their mounts, so old lanses do fit and can be used. But it is _not_ "more so" with Pentax, it is less so since Pentax did not bother to make their new cameras fully compatible with the whole point of the K-mount they once invented. On a Pentax DSLR you have to stop-down meter using old K-lenses since the new bodies cannot mechanically feel what aperture the lens is dialed in to, they do not have that little pin sticking in the lens on the cartridge side of the mirror, the camera house pin that feels the aperture ring on the lens. Probably because Pentax wants people to buy new lenses instead of using old ones, by making old lenses clumsier to use.

This is not true of the more recent Pentax DSLRs, including the budget K-x. I just came inside from shooting origami boats in the park across the street with mine with the 50/2 SMC-Pentax.

This issue that you raise--backwards compatibility--is far less true of Pentax than Nikon, Canon, or any of the other major players (quality is another discussion which... to each their own ). As noted by Karen Nakumara, who has more experience with these things than all but a tiny percentage of people in the universe:

"The famed "backwards compatible" Nikon SLR system has enough incompatibilities and "buts" to fill an entire wall chart."

http://www.photoethnography.com/Clas...iPentaxME.html

But don't take her word for it:

http://www.nikonians.org/nikon/slr-lens.html

In fact, if you type "nikon lens " into google, "... compatibility chart" is second-ranked behind only "... reviews".