[Aavso-photometry] Screen for "dome" flat?

[Jeff Hopkins]

Hi Tim,

That is similar to what I did.  While like you  I put a defuser over 
the corrector plate. I do not consider it any more in the optical 
path than whatever is used to produce the light and reflection (white 
board, light bulb). Some people even use a tee-shirt, but I have 
never had good luck with that.

JeffAt 09:52 -0700 05/11/2008, Tim Crawford wrote:
>Jim,
>
>I purchase white "boards" at a local artist shop; they usually have 
>them constructed of several different materials and sizes (think 
>big).
>
>Then I bounce a 40 watt GE "Reveal" light bulb off of the white 
>board(s) while the scope is  pointed at the "boards."  Your distance 
>is going to be a matter of experimentation.   I have the bulb 
>installed in a reflector and added a rheostat switch to the line so 
>I can control the brightness of the bulb
>as differing levels are required depending upon the filter.
>
>Simple and seems to be reasonably effective.
>
>I will confess that for awhile I "foolishly" (IMO) used an opaque 
>screen over the corrector plate until a friend asked me why in the 
>world I would introduce something in to the optical path that is not 
>there when I am imaging.... Never used it again.
>
>ad Astra
>
>Tim Crawford CTX
>Arch Cape Observatory
>
>http://homepage.mac.com/windwalker1/ACObserv.htm

-- 
Jeff Hopkins
HPO SOFT
Counting Photons
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