lens mount.

I am hoping to buils a 645 to K mount. Has anyone any experience of removing a K mount from a lens. Are the screws glued in. I cannot shift any of them.

regards Thoramay.

I have not tried with a Pentax lens but I've had no problem removing Sigma or Vivitar bases to remove the Ricoh pin.

With an appropriate size and correctly tipped jewellers screwdriver it is quite easy.

There may be a microscopic amount of thread lock, but once that has cracked the screws are easy to remove.

I have just tried it on a 28-80 - five screws removed and then replaced in under a minute.

Tried all the obvious routes. No success. It is a Pentax M version 135 F3.5. lens. Screws are stuck real tight. Just my luck. Have to try another route for the adapter.

regards Thoramay.

Are you trying to change the mount of the lens, or is it the K mount flange you are trying to preserve?

Seems a shame to do it do a decent lens like the 135mm. There are plenty of junk lenses available for a couple of quid that a K mount could be salvaged off.

I was going to say the same ... I might even be persuaded to part with a cheap lens or just the mount!

I've used the flange from an old teleconverter before and you can buy Extension tubes with a metal mount for around £5.00. Maybe Thoramay is trying to convert the lens to 645 mount though.

Have a read of:

https://www.pentaxuser.com/forum/topic/645-to-k-adapter--20999

Have succeeded. 645 to K mount.

I took the M42mm route.

Johnwhit kindly donated the 645 lens cap. Thanks John.

First used a K body mount to M42mm screw thread.
Connected to this is a M42mm extension tube 10mm.

Made a hole in the cap to fit a flanged adapter with M42mm thread. This was cut off one of the other extenders.

With the flange inside the cap, screwed the threaded end into the other end of the 10mm extender. All nice and tight.
Its my first attempt.

I would prefer to use the K mount fitting from the end of a lens but, as you know, could not shift the screws.

If anyone has such a end fitting they do not need, then I would be grateful for the offer. The 135 lens cost a tenner from my co-operative local photo shop.
My preferred method, using the lens end mount would be a stainless steel tube with a 49mm inside thread at one end and an external 49mm thread the other.
I am also chasing a Pentax K mount to a 49mm external thread. Just need to check that the length of tubing is right.

regards Thoramay

Get a small, 1mm drill bit and drill out the screws!

Since the lens is no use without its mount, heat up the mount with a hairdryer and then try removing the screws.

You're very welcome. You really do need a quality screwdriver to get out those screws, Phillips head (not posidrive). I think the size is "00" or "000", the lettering has worn off mine. They are tight and rightly so, I'm not sure if they use a form of locking compound but I think they're just made to very fine tolerences.

Regards,

John