I am no expert. If this subject is discussed elsewhere on the forum, I haven't found it.
Consider this information very basic. If you have more or better useful info, please add to the thread.
Lens size is determined by the diameter of the glass. Frequently measured in millimeters. (50 mm is about two inches, 75 mm is about three inches, 100 mm is about 4 inches).
Focal Length is the distance from the center of the lens to where the glass has the largest/clearest magnification. In...
Solar fire lens tutorial
Consider this information very basic. If you have more or better useful info, please add to the thread.
Lens size is determined by the diameter of the glass. Frequently measured in millimeters. (50 mm is about two inches, 75 mm is about three inches, 100 mm is about 4 inches).
Focal Length is the distance from the center of the lens to where the glass has the largest/clearest magnification. In...
Solar fire lens tutorial