Small scope shootout from Solstice Canyon, Malibu, 10th of Nov 2012

This has probably been in the works for a while now. I have not done a side by side shootout between two similar aperture scopes for some time. Seeing how my small'ish scopes have continued to "breed", I felt this was as good a time as any. These two scopes also compliment each other very well as I can use one of them to take quick peeks, whilst the other goes on it merry electronic way, whirling and clicking as it searches out its quarry. The two scopes I am referring to are my Orion SkyScanner 100mm and Celestron NexStar 102GT. One is a newtonian refractor, and the other a long focal length doublet achromat. Its funny how one equates to a 100mm reflector as being a small beginner scope, while a 102mm refractor is regarded as a serious intermediate scope. I have also not had such a "big" refractor in my arsenal, since selling both my short tube scopes back in oz (Orion 80ST and Synta 102mm f/5). I also briefly owned a really dodgy chinese made "plastic" tubed 90mm ST, which I obtained from Hong Kong some years ago that was great for terrestrial views but terrible for night sky views.

 

Anyways I have had the Celestron NexStar 102GT for more than a month now and have had time to work out all its idiosyncracies and  kinks. There were issues with getting the GOTO to work properly, optimizing the visual views, etc etc. See my last blog post about this. The GOTO now works really nicely and battery life seems to be very good despite what a lot of people have mentioned, so much so I don't feel the need to get a Celestron Power Tank (well I did consider getting a cigarette lighter power cable). I also noted that it was pretty cold that night, maybe not as cold as Pinos on my previous trip. The batteries and the GOTO did not fail me this time. Thank goodness.

I arrived at my semi rural Solstice Canyon site at a little past 10.30pm and set up my scopes side by side (literally). My Orion SkyScanner found itself perched on its usual mount, the Orion Paragon photo tripod. Setting up the 102GT was much easier. Just slide the dovetail of the OTA into the groove of the fork mount, plug in the hand controller and the power source and there ya go. I tried to replicate similar FOV and magnification's for both scopes since the the SkyScanner has about half the focal length of the 102GT (400mm versus 1000mm) by using my lowest powered ep, the 13mm Orion Stratus in the SkyScanner for 31x magnification and the 24.5mm Meade SWA for 41x. I then proceeded to hit several DSO's over the course of three hours. Familliar objects were easy, whilst with harder ones, I tried to copy the starhop the GOTO used.

Started off with showcase objects such as M42, the Orion Nebula, M45, the Pleiades, M31, the Andromeda Galaxy, M33, the Triangulum pinwheel galaxy, M76, the Little Dumbbell Nebula, NGC 2392, the Eskimo Nebula, NGC 7662, the Blue Snowball Nebula, M1, the Crab Nebula, M78, Orion reflection nebula, M79, Lepus Globular as well as some open clusters such as M35 (Gemini), M36/37/38 (Auriga), NGC 869/884 (Perseus) Double Cluster. Later in the night I decided to trawl the galaxy rich Fornax/Eridanus region for southern galaxies. It was fun to once again visit NGC 1365, 1300, 1316 among others. Here are my eyepiece impressions of all objects:

M42 (Orion Nebula) Nice looking. Outer tendrils more obvious without the NPB filter in place when looking through the refractor. Wider FOV in SkyScanner made for a more asthetically pleasing views, but with NPB in place.
M45 (Pleiades) Cleaner looking stars in the refractor but once again the SkyScanner threw up a nicer wide FOV view
M31 (Andromeda Galaxy) More contrasty views of the galaxy's dust lane in the refractor, but I liked the wide FOV views given by the SkyScanner as it showed the full expanse of the galaxy
M33 (Triangulum Galaxy) The wider FOV tended to concentrate the galaxy better, but the refractor threw up very contrasty views at its lowest magnification
M76 (Little Dumbbell Nebula) Both scopes gave better views of this smaller object, although the refractor again wins out with its more contrasty views
NGC2392 (Eskimo Nebula) Its a running trend here. Small objects requiring magnification do better in the refractor. Its amazing how little if any false color there is on these objects. I can start to make out the dual ring nature, which is way more obvious in my 10".
NGC7662 (Blue Snowball) Again views in refractor wins here. Little internal detail is visible though. Small planetaries are best viewed at ridiculous magnifications in big scopes, such as my 10"
M1 (Crab Nebula) Again the refractor wins out. The nebula just seemed more defined with "harder" edges
M78 Much like the crab nebula, the edges just seem more defined in the refractor. Maybe I have to flock my SkyScanner.
All galaxies appeared better in the refractor, probably due to its superior contrast. The background was just darker in the refractor. I am wondering if flocking the SkyScanner OTA would level the playing field.
Larger open clusters looked prettier in the SkyScanner, if one ignores the seagulls cause by coma closer to the edges of the FOV. Smaller open clusters looked very pretty in the refractor, again due to its superior contrast.

So in conclusion, planetary views are heaps better in the refractor. I also found that the refractor can be pushed to higher magnifications with minimal image breakdown, in comparison to the SkyScanner. I generally found the images optimal at about 100x magnification for the SkyScanner. In that aspect, the refractor threw up nice and more contrasty images of small planetary nebulae and planets. Brightness between both scopes was on par, and detail in objects was just a tad better in the refractor. I am not sure if this is due to the unobstructed aperture of the refractor, or its superior contrast, since viewing DSO's is all about the contrast between the sky and the object in question. The other thing that was annoying in the reflector that was absent in the refractor was the size of the sweet spot where the field remained aberration free. With the short focal length reflector, the off axis coma was annoying as anything that was not in the center of the FOV was distorted (i.e. hard if you were trying to sweep up some planetary nebula as you could not distinguish the stars from the planetary nebula). So which scope would I choose. This is a hard one as both scopes compliment each other so well. Both fill a roll, even when used in tandem. The big plus is both scopes are light and can be carried in one sitting when using my Orion carry bag. I rather carry these two scopes than the C6 by itself on the Vixen Porta, my previously most used scope. That says a lot. The Orion SkyScanner is a great waiting for the GOTO, super duper quick wide field scope. And speaking of wide field, the SkyScanner is an excellent panning scope. This is something I cannot do with the longer focal length 102GT refractor. Also using the dob mount is pure joy when panning. The GOTO mount cannot be used for panning as it can only move manually in altazimuth.

So what's up next? I think I am getting shootout fever. I recently purchased some small scopes over the Thanksgiving/Black Friday period and I am hoping to pan some of these scopes off to newbies with the hopes of igniting their passions for stargazing. The two interesting scopes that will go head to head include a Orion 3 inch SpaceProbe which I got for a good price on clearance from the Cupertino Orion store, and also a 70mm Celestron Powerseeker I got off Walmart. And when the dust finally settles, I will pit my most used scope to date, my Celestron/Vixen C6 on Vixen PortaMount against my Celestron 102GT. I am sure the GT will hold its own in terms of planetary and lunar views. DSO's might be more of a stretch...stay tuned!!!!!!!!!!!!!!!!!

i.e. photos taken by Terry Nakazono on a different observing run. We were only there from 11pm to about 2am.