Re: ATM Followup: Copier Drums & Lenses.

[andydtg@phoenix.net]

Bruce Swayze wrote,

>The other thing that I'm not sure about is that it has a stop inside the
>lens cell.  While the whole thing is about 3" in diameter, it looks like the
>stop inside effectively reduces the aperture to only about 50mm.  Anyone
>have any comments?  Maybe I'm wrong about how the lens gathers light.

To find the actual aperture, put a *bright* pinhole on axis at the
focus & place a white screen in front of the lens. The diameter
of the illuminated circle on the screen is the effective aperture
of the lens.


Andy Saulietis / DTG Alt-Az-Fp Drive Systems
HDPE Worm Gears, Custom designs & Machine work
12617 Harriet Ln
Santa Fe, TX 77510 USA
409-925-8854 Voice/Fax
e-mail: andydtg@phoenix.net