ATM 14.5........focal legnth..72 .312

["natsp" <natsp@alltel.net>]

thats if i measured right:
 i placed the knife blade even with the face of the lamp housing with a
straitedge and moved the tester so the image projected onto the blade was
exactly the same size as the hole, it even showed tiny irregularitys on the
edge of the light hole,in the projected image..
 then, i measured the distance from the mirrors edge to the lamp housing-and
knife blade.
when using the foucault,on the measured axis,how much travel should the
knife edge have
behind (past the frontedge) of the lightbox?
should it be equal to the amount of
travel in front of the light box?
does the light box size make a differance, as the larger box changes the
distance of sight when Sighting down the side of the light box?
sorry for all the ????
i built the slit type because it was easyer for me to understand.
i have looked and read about  many foucault testors and their operation
but i cant grasp it yet.
i think my mirror is a good sphere
or my foucault blade does not have the right amount of travel past the light
source (im going to make up a coulder mask i guess)
time to parabolize..............mabie.............?
take care
stan