By Scott Sparrold
I LOVE this method of understanding first order imaging in a lens. This mechanical nomograph runs in my head to provide powerful insight!
Are you algebraic-ly challenged like me? Do you struggle to intuitively understand the lens makers equation (1/image=1/focal_length+1/object)? Then please take the time to understand this graphical method of understanding a lens. It is very powerful! It is an imaging nomograph or a mechanical model that explains image / object relationships.
For a step-wise explanation please see these links to animated pictures / descriptions:
Editorial with me and this imaging method:)
As a sneak peek, see below. Focal length fixed, Conjugate changes describe by rotating the "load line"
The various sign conventions for the lens maker's equation is annoying and I therefore prefer an imaging "nomograph". A nomograph is pictoral representation to convey technical and sem-technical information. Per Nomography by A.S. Levens Wiley 1937. Here is a great web resource for nomography. I love these things, but I am an amateur nomographer!