This short video shows how to find the focal length of a simple lens (for focusing on infinity)- useful for building camera obscuras or simple box cameras.
WQW. Quickest way to find Infinity Focus. That way you can plug it into the formulas and calculators. Or know where to put the secondary. I want to build an optical bench but that is way down the list. Took apart an old pair of binoculars to re-purpose as a scope. Thanks
Hiya, middle normally (nodal point) with a simple lens like the one shown. Some multi-element photo lenses have the nodal point is actually behind the lens, confusingly!
