Horses for courses

[pmrid (Peter)]

I had the opportunity to try an experiment on Sunday morning - I had 2 quite different scopes image the Horse/Flame area using NB filters with different Bandpass characteristics in the same temperature and the same exposures and with cameras with the same sensor.
The scaopes were a WO FLT110 and a Vixen R200SS.
The cameras were an ATIK 4000 and a SXVR_H16.
The filters were Astronomic new series 12nm and Baader 8.5nm sets each in a SX wheel and each guided via Maxim with Lodestar cams. The Vixen was on a Titan and the guiding was pretty tight. The WO was on a G11 and the guiding OK but not as good as the Titan.
Exposures were at minus 20 and all were 5 minutes with 8 or 9 per filter.
The results are interesting.
I'll post them for comment.
The image with the reflections is the WO/ATIK/Astronomic combo and the other is the Vixen/SX/Baader combo.
All images stacked in DSS and processed in CS5.

Peter

[jjjnettie (Jeanette)]

To my eye there is only a gnats difference between the two results.

[Tandum (Robin)]

Some square stars and weird diffraction spikes in the first one. I guess that's the vixen?

[pmrid (Peter)]

Originally Posted by Tandum

Some square stars and weird diffraction spikes in the first one. I guess that's the vixen?

To my eye, the Vixen/Starlight Xpress image is dirtier. And lacks the contrast of the ATIK. And the extra aperture (8" vs 4.5") and narrower bandpass in the Ha filter (Baader) hasn't produced the visible improvement in sharpness and contrast I was expecting. Also, the shape of Alnitak. Whoaaa!! The thick spider vanes on Vixens are said to have a tendency to square off stars and produce fat spikes. But I can't see what is causing that odd effect on the bright star.
With the WO/ATIK conbo, the image is cleaner I think, and sharper. But that damned reflection (in all filters in that same corner) has me a bit concerned.
Peter

[RickS (Rick)]

Peter,

Are you sure the Vixen collimation is spot on, Peter? At f/4 you'll need to have it just right to get the best results.

Cheers,
Rick.