I've done that! But instead of using a screw to hold the adapter to the lens I used lok-tite (spelling? whatever..) witch basically glued the adapter to the lens. I think I even used the same technique for finding the position of the slot. Instead of a dremel I hand drilled VERY carefully.
After all that work I used the lens maybe 5 times before replacing it with a k-mount equivalent. Christian Skofteland [EMAIL PROTECTED] ----- Original Message ----- From: "William Robb" <[EMAIL PROTECTED]> To: "Pentax Discuss" <[EMAIL PROTECTED]> Sent: Monday, October 28, 2002 8:46 PM Subject: Screw mount to K mount: A permanent solution. > We were discussing the possibility of permanently mounting an > M42 to K-Bayonet adaptor to a screw mount lens some time ago. > On the surface, it is quite an easy modification to make, with > some caveats. > The biggie is that some screw mount lenses don't have a wide > enough base to catch the locking pin on the K-mount camera. > The 17mm fisheye Tak that I wanted to modify has a large enough > base. > The mod is incredibly simple. > You need to remove the spring clip from an M42 adaptor. This is > done simply by removing the screw that holds it on. The adaptor > I used had the spring removed already, so I had to find a > replacement screw to fit. Fortunately, I had dismantled a Nikon > FG-20 some years ago, and had kept a film tin with all the > little screws, so I was able to find a screw fairly easily. > On the adaptor that I used, the screw hole for the spring clip > was not quite drilled all the way through. I just forced a screw > through, enlarging the hole in the process. I then burnished the > metal bits off the inside of the adaptor. > After that, I mounted the adaptor to the lens, and torqued it on > fairly tightly. I just put the whole assembly onto a camera body > and turned it quite tight. > After that, I put the screw into the adaptor, and tightened it > until it locked the lens onto the adaptor. I had to thin down > the screw head a wee bit with the Dremel and a small cutting > wheel. > > The next part is to figure out just where to put the notch in > the lens mount for the pin. > > I decided the best way was to put a bit of ink onto the locking > pin of a dead camera body, and mount the lens while holding the > pin in, then releasing the pin when the lens was mounted. > Depress the lens release and hold it until the lens was off, and > I had a nice little round outline in the lens mount where the > pin wanted to be. > > After that, it was a simple task to cut a small slot into the > mount with a Dremel and a small rotary file that came with the > tool. The Dremel does tend to try to dance around a bit, and I > scored the mount in a couple of places, and I seem to have gone > a tad deeper than I needed to, > > It ain't the prettiest, but it worked, and my 17mm Fisheye Tak > can be mounted just like a K-mount lens. > > William Robb >
