I have a "Lumicon 2"" Thread-In Focal Reducer, 48mm Male Filter Threads, Attaches to 2"" Eyepieces, Attaches to 2"" Diagonals, Made in the USA 2".
I wish to determine the focal length of this focal reducer so that I can determine if it is suitable for its use photographically as well as visually.
How would I go about determining its focal length?
Any easy suggestions more than welcomed.
Ive attached a photo of the beast - cant get any information as Lumicon have ceased production of them.
Thanks, Allan
A quick way would be to focus the Sun on a sheet of white paper, just by holding the reducer in your hand, as I assume the lens will be a positive lens rather than negative lens, such as a Barlow?
I know that you don’t require this stuff, but all the usual warnings about never looking at the Sun through any optical instrument and being careful of the intense heat in the focused solar disc apply if anyone experiments with optics and the Sun.
Dennis, I think you are correct as it is a positive lens except one problem, clouds here in SE Qld just wont go away so can't see the sun.
All joking aside - I thought this would be the best way and can check my results with the Meade f6.3 reducer which should give 87mm.
