[Aavso-photometry] Halogen lamps for flats

[Barbara G. Harris]

I would think that you would need to take the filter off to get U flats (but
I would wait for others to answer).  How many lumens will that 20 watt
halogen lamp put out?  How many are you using?  I have a large light box for
my 16" Meade SCT(I don't remember the exact dimensions of the box) but I use
4 15 watt incandescent bulbs in my light box with a rheostat to take all of
my flats except for the I filter, then I switch over to 7.5 watts.  The 15
watt bulb is 110 lumens and the 7.5 watt puts out 55 lumens.  Usually
halogen lamps are more efficient and require a lower wattage than an
incandescent light to get the same light output.  I usually shoot for 5 sec
flats and adjust my light output to get a 5 min flat at about 40% full well.


-----Original Message-----
From: aavso-photometry-bounces at aavso.org
[mailto:aavso-photometry-bounces at aavso.org] On Behalf Of Brad Walter
Sent: Sunday, April 12, 2009 12:10 PM
To: aavso-photometry at mira.aavso.org
Subject: [Aavso-photometry] Halogen lamps for flats

I am about ready to mount some 20 watt halogen lamps in a new light box. The
fixtures include a UV filter which is required for normal household use. Do
I want to leave the UV filters in or take them out? My inclination is to
take them out since I want to use the light box for the full UBVRI spectrum
and the spectrum of a "halogen bulb in a desk lamp, which would normally
have the filter in place, rolls off sharply above 500 nm as shown on the
ledmuseum.org website . 
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