M42 lenses on a Nikon F body.... with infinity focus

[480sparky]

OK, I already know that a glassless adapter for sticking an M42 lens on a Nikon F-mount body will lose infinity focus, but my question is: How far from infinity can one focus? 100 feet? 50 feet? 20 feet? 10 feet? I'm sure this will vary with different lenses, but is there a general rule of thumb?

Just asking before I drop 3400 dimes on an M42 lens.

 

[Derrel]

I just tried a 135mm f/3.5 Super-Takumar on a glassless m42 to F adapter, and the far focus when wide-open was just a shade over 15 meters, as measured by my 300/4 AF-S's focusing scale.