"That's the 'science' of it, but it's really just common sense." It may be common sense to you (someone who's been working with cameras for 20 years), but to a clown like me who struggles just to use a disposable camera, it's very insightful stuff. I've never really thought much about it before Poser. So keep the info comming - like you said it helps to know the rules (or how things work) before you try to start bending them. Unzipped