Dear Agray24:
The PIPE here...and on a page here at PentaxForums.com. specifically at
https://www.pentaxforums.com/forums/post-your-photos/37893-1st-serious-trial-...0mm-k100d.html , whre I relate my experiences that sum up my very first serious shooting session with my veteran Vivitar Series One 70-210mm
all manual zoom telephoto lens on my digital Pentax K100D camera.
That lens of mine was purchased quite some time ago (the better part of twenty years ago!) from KEH.com, and it certainly did NOT let me down on the K100D!
Setting the K100D up to use the Vivitar DID involve setting the camera to "allow aperture ring" inputs when I used the "AE-F" button function on the K100D...the exact equivalent of the "green button" on your K10D...to get a good, usable aperture setting while in "M" manual mode on the K100D's function dial...
...and when that front-of-the-camera switch IS set to "AF" for autofocus, when using a MANUAL lens, the camera will ONLY let you take a photo, IF you're in focus, as AndrewG NY reminded us in this thread, when the "little green hexagon" at the bottom center of the viewfinder (where it exists on my K100D) is lit...I found that out while I was shooting the RC Scale model aircraft photos in my listed forum link, that were shot almost a year ago as I write this.
I'm STILL out of work (almost a year now)...so NO "new-to-me" lenses for the present. IF the Sigma 135-400 "Li'l Bigma" Pentax-mount AF zoom telephoto lens I spotted up at KEH.com late last week for about $360 manages to stay there long enough, and I DO end up getting back to work in the next couple of months, I MIGHT get that, as my 1980-vintage "film burner" Pentax K1000SE can use it too...and there IS another potential good choice in the Sigma 70-300 APO DG zoom tele lens for a bit less money (even the new ones) if that 135-400 can't be found anywhere in the future.
Hope you can get used to trying the "AF" mode with your manual lenses, after setting your K10D up to "allow aperture ring" usage...just check your manual for an entry in its index about that above term about how to do it, and you'll be off and running with your manual lenses on your K10D...
...best of luck!
Yours Sincerely,
The PIPE!