which adaptor do I need for my k-r camera

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

If the old lenses have a K mount bayonet fitting no adapter is required. If they are Pentax screw mount (42mm) then a Pentax screw to K mount adapter is required.

Adapters can be obtained cheaply on eBay but the best ones are Pentax original ones which are rather expensive but are much more reliable and easy to use.

To expand on Archies reply:

If you bought K mount lenses that wont fit then we would need more information to determine why they wont, there is also a variation to the K mount used by Ricoh SLRs (PKR mount) these can get stuck on the body if you persist in trying), until you become a bit more familiar with the Pentax K Mount history I would suggest you check on here before trying to attach anything to the camera.

Oh and welcome to the forum

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

If you look at the mount you will see a raised flange which protects the aperture actuating lever, on some lenses this can be quite long and foul on the inside of your DSLR (Film SLRs had more clearance)

Is that the problem?

Alan makes some good points.

I note that they are Sigma lenses, are you sure that they have a Pentax mount? Sigma makes lenses that fit many different makes and they could be for Nikon or Canon cameras.

If you could show us a photo of the lens mount it would help.

Usually there is some indication on the lens body or mount as to which make they're intended for.

Sometimes it'll simply be N for Nikon, C for Canon, etc.

If you see P, Pentax or PK then if should fit.

Try this as a useful site for mount identification;

http://rick_oleson.tripod.com/index-99.html

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