first time trying to use an older lens on my DSLR

ie a pentax SLR (M50/1.7)on K200 camera

the lens fits but the shutter wont press down

any idea's?

how can I get the lens to focus/work

thank you

first time trying to use a pentax SLR (M50/1.7)on K200 camera

the lens fits but the shutter wont press down

any idea's?

how can I get the lens to focus/work

thank you

the mount looks the same on the old lenses and my k-r camera, but they dont seem to fit correctly like my other lens does, they wont stay in place

I have a new k-r camera which came with one lens. I cant afford the DSLR lenses so I bought a couple of old slr lenses in a charity shop. I realise I must need some kind of adaptor, which adaptor do I need please? the lenses I have bought are a sigma 200mm zoom and a sigma mini wide 1:28. Any advice welcome. thank you