Mulitple adaptors and Macro effect

I have found a really nice old glass 400mm for sale but it is an OM fit and I cannot find an OM lens to K camera adaptor.

So to make it fit on my K5iis logic tells me I can fit an OM to EOS adaptor to it (which has no lens in it - but maintains infinity - so from infinity point of view nothing has changed) and then fit a EOS to K mount adaptor on to that (again no lens involved in these and infinity is maintained).

I have been advised this will create a stacking effect and infinity will be lost but I cannot get my head round the fact that each adaptor on their own would not have a smaller macro effect but maintain infinity - I am still learning about all this so have probably missed something obvious but any answers would help my sanity.

Thanks

Stephen

have a look here link

the EOS flange to film distance is shorter than that for K mount, so no purely mechanical adaptor is possible to go EOS lens to K body without losing infinity focus, sadly.

Sometimes you get partially optical adaptors which do this sort of thing, but they act as short teleconverters and there is an IQ/light gathering penalty.

Thanks for the info - I was chasing a Mitsuki 400 on ebay but it was OM mount- however then scored another one with M42 - so adaptor for that will not break the bank and infinity will be maintained without the need for any glass and light loss. So all came good in the end

M42 should be much easier, there is an official adaptor which maintains infinity focus.

You have to use one of the ones which fits inside the mount (like the official one), some of the cheap ones extend in front of the camera body and these will loose infinity.

Some people have reported problems with build quality on the cheap versions of the in mount adaptor, there are small springs involved which could potentially come loose and damage the camera. I wouldn't go as far as to say only use an official one, I've had cheap ones which were fine, but it's something to check before you put it inside your expensive camera.

thanks Mongoose re poor quality adaptors - I'll will certainly check the one I purchased out thoroughly ( when it finally arrives really cheap from china:shock - I'll probably bin it now after your advice -that could have been an expensive step on the learning curve!

The springs referred to by Mongoose are easily removed; they're held in place with a screw and simply serve to lock the adapter into the mount. Take the spring off; no harm will be done and the adapter will work ok.