blue23rose said:That is a lot to digest, Asa. Physics and math are not my strong suit. But I'm sure if I purchased the kit, I would be able to figure it out just by playing around with it and that would help me understand.
I went to college at the age of 41 and made beginner's algebra my very first class because I had never had it and had no confidence that I would pass. However, I found that I liked it and made straight A's. I had wonderful teachers in both the beginner and advanced algebra classes I took. But there were times when I would have to sit and study a problem for two hours before the answer would click. I have a feeling learning this will be the same way. I appreciate the time you are taking to teach it.
A pleasure, Vickie. Fortunately, where the rubber meets the road here (or your eye meets the camera), math and physics go out the window apart from the fact that they're just practical constraints for the question, "is the picture in focus or not"? In other words, you really don't need to be able to explain the effects of gravity with a series of equations in order to be able to hop a fence.
The product of the math/physics of using magnifying lenses (versus pointing-and-shooting) is just one practical thing - and if you understand that one thing, the rest doesn't need to come into play at all.
With any lens, there's a "too close". Every lens has a minimum focusing distance. But with magnifiers attached, there's a "too far", also. Instead of being able to shoot from the minimum focusing distance to infinity, there's a limit on the maximum focusing distance. (And with some combinations on some lenses, the distance between the minimum and maximum focusing distances becomes very narrow indeed).
The practical solution to that (until you habituate a sense of where it is for the combination) is to simply put the camera to your eye near the subject and move closer/farther from the subject until you acquire focus. At that point you're in range and can use the auto-focus to finish the shot.
No math, no physics - just a little flexibility and trial and error until you get the right point of view and the solution comes into focus. Seems like there's a metaphor in there somewhere...
