Originally posted by johnha It meters off the film plane rather than from the viewfinder. In manual mode it meters before the exposure like most other cameras. In Auto it also meters continuously during the exposure, during long exposures it keeps the shutter open until enough light has hit the film. Pentax give the shutter speed range to two minutes in auto, but several users report it will stay open much longer in very low light.
---------- Post added 11-03-19 at 12:38 PM ----------
Check out LesDMess's review of the LX:
Pentax LX - Pentax Manual Focus Film SLRs - Pentax Camera Reviews and Specifications It’ll stay open until it gets enough light or the battery runs out, which ever is first