Originally posted by BethC To be honest with you I don't know what that means. Can you explain to me?
---------- Post added 08-03-2020 at 02:13 PM ----------
I was actually going to buy myself a K-1 Mark 2, but am bummed if I have to put all the money into either a repair or a new lens I will have to put off buying a new body
The K1 is full-frame. The 50-135 is APS-C format, so while it will "work", you won't be getting all the camera has to offer. If you are upgrading to the K1, you are probably going to be wanting different lenses all around.
As to the other question, there are two focusing systems in use: in-lens motors (the SDM in the 50-135 is an in-lens motor), and the in-body motor (also called screw drive commonly). The oldest Pentax autofocus cameras only had screw-drive, and they do not support in-lens motors. Because of this a few SDM lenses, including the 50-135 are capable of operating with either method. However, if the lens is attached to a modern body, it only wants to focus in SDM mode, not in screw-drive mode. There is a 'hack' of sorts where one changes the firmware on the lens so that it always thinks it's on an older body so it always uses the screw-drive. The downside is that it is a little noisier. The upside is it is nearly 100% reliable and should last more or less forever. If you have any older or more affordable lenses that make more noise when focusing, those are screw drive. That's pretty much what a converted 50-135 will sound like. It's not terrible, and it's a low-cost solution to your problem.
One of the users on the forum, Uncle Vanya, will do the conversion for you for a modest fee, and return your lens to you functioning with screw drive. Send him an IM and I'm sure you can work it out with him. You can find a posting from him in the marketplace here on the forum:
https://www.pentaxforums.com/forums/24-photographic-equipment-sale/311609-sa...nversions.html