Sorry if I am posting this to the wrong forum, but I have not seen any that really pertain to this type of question, and I figure the MF film users here would be the best resource. I am gradually getting what I feel is a good understanding of the Zone System and how to use it. I use a Mamiya 645e with the center spot meter. Ok... I hope I can explain this so it makes sense. First I will get right to my question. Why does using a grey card to meter your subject give you a correct reading, when according to the Zone System, the objective is to CORRECT the meter reading which is setting the camera to acheive 18% grey? As an example: Say I want to expose correctly for some shadow areas in a landscape scene. I determine this area should be Zone 3. Ok... I take the meter reading, and according to the Zone System, I shoud set an exposure compensation value of -2 stops. That makes perfect sense to me, because the meter trys to place the shadow area up into the Zone 5 middle grey area, thus making it too light, ... so I use the negative exposure compensation to bring the exposure back down to where it really needs to be for correct exposure of the shadow area. So far so good. Now here is what I cannot get my head around. Perhaps I am wrong, but I am thinking that if you use a grey card, say on the same shadow area, and meter off that, then you do NOT have to make any exposure compensation. Is that correct? By using the grey card, are you still not placing the shadow area exposure up in Zone 5, where you DO NOT want it to be? I just cannot grasp how using a grey card can "override" using the Zone System for any selected metered area. I hope this made sense, and some kind folks here can "enlighten" me a little on this. Thanks so much.