Thanks for the kind words Richard. Your shots are also lovely and
very interesting on the color side. I spent quite a bit of time on
your website intrigued by the images and methods.

The CN-212 is one of my favorite, all-time telescopes. It performs
VERY well as both a Newtonian and a Cassegrain. What many people
don't know is that it is a corrected Newt with a lens assembly at
the focal point in Newt mode. This allows it to perform well for CCD
work. I use Newt mode for astrometrics of asteroids, deep sky and
lots of variable star work. The cass mode is excellent for lunar and
planetary work. Collimation in both modes is a lot easier than many
people suspect. Tuning up one mode does not hurt the other at all.
Tools come with the scope to get a good (not excellent) colimation.
Fine collimation is then done at 600x with a bright star on a good
night. I have an online review at the following URL with some more
details....
http://www.regulusastro.com/regulus/papers/takcn212/index.html

~johnb
http://www.regulusastro.com/



> That's a nice crab John. Hey how do you like the CN212? Do you use
it
> mostly as a cassegrain or as a newt? How about collimation of it
in
> Newt mode, is it difficult?
>
> Here is a Crab I shot last week in between storms. I used a C14
and
> an FLI Dream Machine camera. I also used Custom Scientific 3nm
FWHM
> [SII], Ha, and [OIII] filters. I did a second and third version
using
> an [NII] filter with the others.
>
> When you combine [SII], [NII] and Ha all of the data is in
the "Red"
> portion of the visible spectrum. Making a tricolor like I did
gives
> you some nice separation of those emission lines in a way that you
> cannot see with an RGB image. Looks weird though....
>
> [SII]=Red, Ha= Green, [OIII] = Blue
>
> http://www.rdcrisp.darkhorizons.org/m1_crab_nebula_S2HaO3_page.htm
>
> [SII] = Red, [NII] = Green, Ha = Red
>
>
http://www.rdcrisp.darkhorizons.org/m1_crab_nebula_S2_N2_ha_page.htm
>
> finally here is an image made from [NII] and Ha only. These
emission
> lines are only separated by 2nm so it was interesting to me to see
if
> my filters could really differentiate between the species:
>
> http://www.rdcrisp.darkhorizons.org/m1_crab_nebula_ha_n2_page.htm
>
>
> Happy New Year!
> Richard