Here is my next guide to adapting vintage lenses. M42 is one of the most common adapters people need because of super popular lenses like the Helios 44-2 or other Soviet Union lenses. These adapters are typically cheap (around 10-20 dollars) and simply designed. It’ll normally just be a screw-on metal ring, depending on the camera. I’ll start linking for each brand below.
Canon M42 adapters
Nikon M42 adapters
Sony M42 adapters
Fujifilm M42 adapters
Hope this was helpful. I took some time to pick out the most affordable adapters because, in my opinion, it is not worth it to spend so much money when you could get a great product that works great for cheaper. I am a big fan of the company Fotasay. They make the most affordable products and everything I have gotten from them has worked great.
Thanks, Trip