Re: a Good Idea for taking flats

[Tom Droege <tdroege@veriomail.com>]

You all may recall that I have  (Well, I think Mike Watson actually built 
it.) built a Norman Molhant light box.  This is a white box looking at a 
screen which is illuminated.  The idea is that the light bounces around 
inside the box and so results in uniform illumination for the screen.  I 
will have to dig it out and try it.

I also have a piece of milk glass that I was going to install in Dead 
Barney in the flat box.  I can try to take some of this data with various 
schemes if someone wants to work on the result with some data to see what 
gives the best result.  Contact me privately.

Tom Droege

At 03:28 PM 11/7/01 -0500, you wrote:

>   A very wise astronomer at Lowell Observatory has just suggested
>another way to achieve uniformly illuminated images with high
>signal levels:
>
> >      It seems to me as though the way to do flats is by putting a piece of
> >      well- and finely-ground glass like a filter in front of the lens 
> and aim
> >      the camera at either twilight or the Moon or even a streetlight or 
> just
> >      any light that's say 10 meters or more away. ...
>  ...
> >      The best thing about having a piece of ground glass or translucent
> >      milk glass screwed right into the front of the lens is that you 
> can use
> >      just about any light source at any distance and at any time
> >      --- none of this getting twilight flats in a hurry at dusk or 
> whatever.
>
>   I'm very glad that wise astronomers read the TASS E-mail lists!
>Thanks, O Wise Astronomer!
>
>                                                  Michael Richmond