[js2]

It may be a 39mm lens:

http://en.wikipedia.org/wiki/M39_lens_mount

You could start with a T-mount adapter to get to 42mm:

http://en.wikipedia.org/wiki/T-mount

http://www.adorama.com/LNTMEOS.html

Then a 42mm to 39mm step-down adapter ring:

http://www.amazon.com/Fotodiox-M39-Adapter-Zeiss-Pentax/dp/B...

Not sure about the clearances, and you may not get infinity focus depending upon how far out the lens ends up being situated from the focal plane of the sensor.

Edited to add: google turned up this direct EOS to M39 adapter:

  http://cgi.ebay.com.au/ws/eBayISAPI.dll?ViewItem&item=110365260908&ssPageName=STRK

But note "DOES NOT allow focus to infinity".

[kjuhyghjk]

The Canon EF mount has a fairly short back focal distance = the distance between the back of the lens and the film/sensor is less than most other cameras so it's easy to make an adapter to hold another lens the correct distance away.

[lotusleaf1987]

Thank you for the help I am going to look into this. I appreciate the links.