[napawino]

Will using an LR9 (1.5v) battery instead of an MX625 (1.3v) change the metering, or harm the camera? I've been using Wein Cell 625's but they aren't lasting as long as I like.

thanks

[stevebrot]

The meter in the Spotmatic uses a mildly-biased bridge circuit and is not voltage dependent except at the lowest levels of meter sensitivity. In other words, a 1.55V silver cell works quite nicely. The battery to use is the Eveready 387S silver cell or equivalent. Silver cells like the 387S are preferred over alkaline cells to the latter's discharge curve. The 387S is a 394 cell with a plastic spacer to provide a perfect fit. When exhausted, simply replace the 394 with a fresh one.

For more discussion, there is a very recent thread on this same topic that touches on the 387S and other options...

https://www.pentaxforums.com/forums/8-pentax-film-slr-discussion/390766-1-5v...spotmatic.html


Steve

[napawino]

Thanks!

[titrisol]

Just make sure the polarity is correct
The test is in the manual