Male canon 40D female Pentax thread adaptor

Thinking of trying my Novoflex 400mm lens on my 40D hence male canon 40D female Pentax thread adaptor. Any ideas or suggestions or pitfalls, please?
Best regards
Rod Warnock

Found this excellent article:
http://photonotes.org/articles/eos-manual-lenses/
Which answers fully what I wanted to know about this query I had.
Best regards
Rod Warnock

Rod,

Thanks for following up with this article reference.