Hello everyone,

Well - I just got done playing around a bit during the last clear
night we had.
As many of you know, I do a lot of photometry of variable stars and
asteroids. This has forced me to place a V-photometric filter in the
CCD's filter wheel. Now... filter wheels are funny things. They are
specifically designed to prevent you, the amateur astronomer, from
having the best of all worlds. Mine, for example has just 5 holes to
fill. No more. Sigh. I had started with a clear, red, green, and
blue filter set. That's 4 filters leaving me with an empty slot for
something else. I stuck a diffraction grating in there for
spectroscopy. Now... where to place the V filter? I kept swapping it
with the grating. This means getting the phillips screwdriver out
and taking the CFW-8 cover plate off to access the filters. What a
pain. What to do?

Well - V-filters are green. Hmmm.... Maybe replace the green filter
for RGB imaging with the V photometric filter? Perhaps! So... that
is what I did. This had to be tried. Imagining all sorts of problems
with color balance, I spent 30 minutes imaging NGC 4565, a favorite
edge-on galaxy of mine in Coma Berenices. The results are pretty
good! The color balance was fine. I tweaked it a slight bit away
from the blue. Also - and this might bother me later on... the focus
point for the V-filter is 1.5 turns away from the R and B filters on
the focus knob. Sigh. Maybe I should try a full BVR filter set with
a matching clear? Hmmm... the plot thickens.

Check the image out at:

http://www.regulusastro.com/regulus/photos/text/ngc4565_lrgb.html

It has short times... so it is definitely not a high enough S-to-N
ratio, but not bad.

Clear Skies, please?

~johnb
#225 Northwood Ridge Observatory