Archived posting to the Leica Users Group, 1998/03/26
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]The MR4 meter is a simple circuit without voltage regulation. It consists (simplistically) of a battery, amp-meter, CDS Cell, and variable resistor in its operational mode. Basically, the CDS cell varies its resistance with light intensity. The amp-meter measures the variable current from the circuit. The variable resistor is used to set full scale adjustment of the meter. Why is this important? Because if you have a meter that is calibrated for the old mercury cells (1.35 V) , and want to use it with the new 1.50 V batteries, you either must adjust the variable resistor or set your ASA lower. How much lower? I would say 10%... 1/3 of an F-stop is fine. Does this remain linear with increased light? Yes it does... one ASA setting change will make all your readings accurate, no matter what the light reading. So.... either get your tech to adjust the variable resistor or decrease your ASA by 1/3 speed... ASA 100 to 80, for example. Your third choice is to buy the CRIS battery adaptor... this will work without adjusting anything. I would review the CL and M6 meter as well if someone would make that available, although from my previous life I know that the M6 is a different animal. Thank You Remove "ZZ" form auto reply address or please reply to address below: Frank Filippone red735i@worldnet.att.net