How accurate are cheap M42>EOS adapters?

[analog_addict]

I bought a M42 adapter from Ebay for 8 quid but I'm starting to think it might not be too great. The reason being that it needs to have the lens exactly 1.46mm away from the EOS mount to achieve perfect focus and for focus markings to match up.

What are the chances that cheapo adapters have such tight tolerances? Does anyone have any experiance with these very cheap adapters, how accurate is the infinity focus?

Thanks!

 

[andya700]

I bought a M42 adapter from Ebay for 8 quid but I'm starting to think it might not be too great. The reason being that it needs to have the lens exactly 1.46mm away from the EOS mount to achieve perfect focus and for focus markings to match up.

What are the chances that cheapo adapters have such tight tolerances? Does anyone have any experiance with these very cheap adapters, how accurate is the infinity focus?

Thanks!

There may be a problem with infinity focus, but as for the focus marks not matching up on the camera lens, is that a problem?
Only you can judge whether or not the adaptor is good, by looking at the results. I would think that the only problems relating to image quality, would be if the adaptor contained a glass element.

 

[DaveKing]

Not sure how much help this is, but I use a K-Mount - EOS adapter with focus confirm and I find it excellent.

When using apertures lower than F4 I usually use the focus confirm to get 'about right', and then use live view x10 to nail it. Either that or I will 'bracket' the focus with 3 or 4 shots.

With apertures from F4 I will just use the focus confirm and it comes out of 99% of the time