Why not try to adapt a very unexpensive M42 lens to your DSLR ?
First step is to consider your DSLR mount.
Nikon users are unluky because if they try to adapt M42 lenses to their DSLR because they will need an adapter ring including a lens to keep the infinite focus. This lens inside the adapter ring produce poor image quality. So in my opinion this is not a good idea to adapt M42 lenses to Nikon DSLR.
For SONY/MINOLTA, OLYMPUS, PENTAX and CANON DSLR ou will need an adapter ring M42 to your mount.
there are 2 kind of adapter rings:
- the simple mecanical ones
- The ones with a chip allowing focus confirmation and inbody shake reduction (if any)
When I started using M42 lenses with my Dyxum D5D (same pentamiror viewfinder as the SONY A200) I owned a simple adapter ring without focus confirmation. I enjoyed even if sometimes my manual focus was nos accurate enought. I spent 3 years using my M42 lenses without focus confirmation. But, I was unable to use M42 lenses indoor in lowlight because my manual focus was unaccurate.
Then I decided to purchase and test an adapter ring with focus confirmation because they are unexpensive now. It is working very well with fast lenses (f/ < 5.6). The focus confirmation is accurate. So, I would say, that the good choice (considering the price) is to buy an unexpensive adapter ring featuring a focus confirmation chip.
The you just have to screew the ring to the M42 lens
Now you can have a look on how to use your M42 lens