On Sat, Jan 25, 2014 at 8:17 PM, Miserere <[email protected]> wrote:
> I found my Tamron 1.4x TC worked just fine. With SDM? I've got one, that everyone says works with SDM, and I don't find it to work that well at all with my DA* 300/4. The optical quality is good, but whenever the camera attempts to AF, it overshoots, and I usually have to attempt AF two or three times to get a solid lock. My interpretation is that the camera AF system measures a phase error 1.4x larger than it "should" be, and drives the lens AF motor more than it should. (With screw-drive lenses, the teleconverter is geared to reduce the amount the lens is driven.) Besides that, there's the fact that the camera doesn't know the change in effective focal length for shake reduction, and there's no record of the teleconverter in the EXIF. I'm eagerly looking forward to a proper 1.4x TC... I just hope I can afford it. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
