Quote Originally Posted by Sean
great info thanks

Forgot to put the minus sign before 20F. The high that day was -20F, and I had the R3 hanging out unheated for well over 4 hours with no mechanical or electrical problems whatsoever. Metering was spot on. I shot a Hasselblad 500 CM that had 1/60 go to 1 second in that weather on a commercial job.

Also, there are several varieties of R4 with different features. I'm not a collector, so I can't list the differences. I'll see if I can find a reference. And I'd love to try an SL2 as well. They are rarer, and more expensive, but are all mechanical and built like a tank.