Originally posted by PPPPPP42 So something that just occurred to me, how does an LX meter off the film before the shutter is opened to expose it?
It doesn't. The system is complex and is a coordination of conventional and off-the-film systems. Based from what can be gleaned from the owner's manual the picture looks something like this:
- There are two metering systems, conventional TTL and OTF
- What is displayed in the viewfinder is from the conventional meter
- Av mode uses OTF at exposure time, though not always purely OTF. High speed measures are taken off the front of the shutter curtain, not the film.
- M mode uses conventional TTL
This distinction allow for an additional clarification regarding LX meter sensitivity. According to the manual, the conventional TTL meter used in M mode has a fairly standard range of EV 1(100) - EV 19(100). Due to the nature of the OTF system, the published and often quoted range in Av mode
is calculated at EV -6.5(100) - EV 20(100) when used with the 50/1.2 lens. The lower end of the range is somewhat less with a slower lens. Likewise, the upper end of the range might be somewhat higher with a lens capable of narrower apertures.
Probably more than what you wanted to know
Steve