I have heard a lot about "measuring focus" but never really understood how to do it. I know to focus with a non reflex camera you need to use a tape measure to get the sharpest focus possible, what I'm confused with is at what part of the lens/camera do I start to measure from? (the back, middle or tip of the lens?) I was also wondering about focusing to infinity, I've read a little bit about it but i was wondering what would be the best situation to use infinity for. sorry if this might be a bit hard to understand, I'm a "noob" to this stuff but I would love to learn more. If anyone could break it down for me that would be greatly appreciated, and if this has already been asked many times then I apologize. Thanks again!