Re: [ATM] Re: Weird Foucault readings

["Bob May" <bobmay@nethere.com>]

OH, the SHAME, the HORROR and the FEARS of doing the Foucault Test!
Trying to do a short FL mirror with 3 zones is going to be an exercise in
frustation and you need to do a lot more zones in order to get a real answer
to the shape of the surface.  There is a calculator that somebody (Nils I
think) did on the number of zones that should be done on any particular
mirror.  When you get enough zones, the zonal readings will tend to be
fairly consistent in the ability to read a zone with the outer zones maybe
showing a shading from one side to the other and that is where you want to
make the edge of the shadow to be the same on both sides of the mask and
hopefully in the center of the zone which is where you are actually doing
the measuring of the zonal reading.
Bob May
http://nav.to/bobmay
bobmay@nethere.com
NEW! http://bobmay.astronomy.net


_______________________________________________
ATM mailing list http://www.atmlist.net/