I got a Mamiya 645j that I'm really liking so far. Thought I'd pick up a metered prism because I keep forgetting my meter and have to guesstimate off the sunny 16 rule. Went to Ebay and there are several available, of course, but I hadn't realized that there are 3 types available - PD, AE and CDS. I have a copy of the manual but don't really see why I would prefer one over another except that the PD has LEDs in it.
Can anyone give me a brief explanation of why one is preferable over another? Should one be appreciably cheaper than the other types?