David Lloyd

David Lloyd

Posted on 01/27/2014

Photo taken on January  6, 2011

1/60 f/2.0 7.2 mm ISO 50

Canon PowerShot G3

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M42 Lens to Pentax PK conversion

M42 Lens to Pentax PK conversion
Some of my most popular M42 lenses that I use on my Pentax K10 I have modified to semi-permanent PK mount.
I use the common M42 to PK adapter, cheap ones are ok for this conversion, and remove the spring clip that is for retaining the adapter in the camera body mount. Some of the cheap ones are known to jam.
Then I lightly glue the adapter on to the lens. I use a tiny amount of contact adhesive so I can remove the adapter from the lens. Or, I screw them on very tightly using this old Pentax front plate with the lens mount. Another method of sticking the adapter to the lens is nail polish, which of course can easily be dissolved with nail polish remover.

It is essential that the spring is removed because if the lens is locked on to the adapter and the spring locks it to the camera you can't get at the spring to release it. It's jammed on!

To lock what is now essentially a PK lens in place I drill a small hole in the lens so the Pentax lens locking pin can hold it in position, and release it like a regular PK lens.
To get the hole in the right place is the tricky part, it can be done by putting the lens and adapter ( without the spring ) on the camera and marking where the pin wants to be on the lens. It's a bit tricky but possible.
What I use is the old camera front plate as a jig. I have removed the locking pin and use the hole as a guide to hand drill the locking hole - about 1.5 mm deep.

In the other pictures it shows me drilling a lens upright on my desk - the pictures are for demonstration only. I clamp the remaining larger bit of the old camera body in a bench vice and with the rear of the lens stuffed with tissue and taped up to keep the swarf out of the lens. Then I gently drill with a small hand drill
Be sure to blow all the swarf away, and you have a semi permanent PK lens.