_zeejet_

Thanks for all the insight. It's likely that the metering range is just not that great. I basically can't get anything to read other than underexposed at f2.8 (no matter how slow the shutter up to 8s) indoors under 60W lights. I still think my particular prism is especially limited. I might just get a waistlevel finder (I hate holding the camera to eye-level) and meter with my Sekonic or iPhone (in a pinch). Also, the PD prism I have has a metering button that turns it on for about 10 seconds before turning off automatically. I think it's a more recent version (has the 1/1000s top shutter speed).

I acquired a Mamiya 645 1000s recently and have only shot two rolls of film on it. My last roll was spent shooting a cityscape at golden hour and blue hour. The metering seemed to work fine during golden hour (I checked it against an iPhone light meter app), but as soon as the light started fading after the sunset, the meter shows under exposed no matter how open the aperture was and how slow I set the shutter speed (I ended up shooting manually using my iPhone as an impromptu meter). I also tested it indoors. The same issue arises where no matter what, the meter shows underexposed unless I point it directly at a light source (in which case, it would show overexposed). The camera is properly set up (lens set to Auto; full light going through the viewfinder; fresh LR44 batteries; shutter speed on camera set to red dot, which defers to the PD prism). Is this normal? I thought the PD prism was really good in low light. And why would it only work in lit situations and then crap out when it's dark?