This had to happen...it has been in a making for the longest time. I have tried most major types of telescopes, both reflectors and refractors. Once class of scope that I have yet to dabble in is catadioptric scopes. These class of scopes marry the best of both worlds. The thing that has always discouraged me from owning one was simply the cost (even the OTA's cost a whole heap more than your standard newtonian, with all the bells and whistles) and the taboo that they are jack of all trades and master of none scopes. Since coming to LA, and moving into the university apartments on the second floor, and having to share my carport with a neighbor, my 10" dob has not seen much action. Now don't get me wrong, this is a fantastic scope. The problem is its weight and girth. Having to lug the scope in two trips down two flights of stairs is just not fun at midnight, when I usually start my observing sessions. Even on oz, the only time when the scope got a whole heap of star time was when I lived in a town house in Toowong, Brisbane, where even then I had to make two trips out. And once you chose a spot, that is where the scope stayed. I once pulled a back muscle moving the scope in one piece. It is doable but not recommended. This is where the C8 comes in. These are classic scopes that have been around for as long as I can remember. Due to the ever expanding scourge that is light pollution, catadioptric scopes, especially the schmidt-cassegrains, or SCT's for short, rose to popularity in the 80's, and still remain one of the most sold scopes today. And the two big names in the SCT business, Meade and Celestron, have been duking it out for years...and they still are. I must confess that I have always been a Celestron man. Must be something to do with my firstscope, which was a Celestron. That and all those glossy brochures. The only other company I like as much if not better than Celestron is Orion, and they are just importer of scopes.
So how did this C8 land in my possession? It was simple really, I was looking out for a used C8 OTA to be used on my Vixen PortaMount. This was to be the 10" replacement as this rig would not sacrifice much in the way of aperture, and still be super portable for trips down two flights of stairs for burb viewing, as well as dark sky jaunts to places where I had to carry my scope a certain distance (i.e. Malibu). For that the 10" was just out of the running. My limit for a used C8 OTA was $250 and under with postage. That means the scope had to be closer to $200 for the OTA, since postage would cost approximately $30-$40 for a package that weight about 16lbs. Most used C8's go for between $250 and $300 (with the newer ones going for even more!) without postage and that kept me on the fence. One option was to buy used OTA's from the AstroPartsOutlet since I have heard good things about those guys. They sell scopes and parts (some literally works in progress...no rack and pinion focuser's, no corrector lenses, etc etc.) and they had two Meade SCT 8 incher's for about $250. They are located close to Mount Pinos so that's not much of a drive for me. It was then when I saw this excellent deal for a used C8 on Astromart for under $200. That was a done deal for me. I was the first person to respond to the ad and before you could hit the buy it now button, it was winging its way to me. This scope was supposed to have a small dent on its side (hardly noticeable to me) and spotty/ smudgy coating (really? it just looks like dust to me!). The scope came with a Celestron 1.25" visual back, a nice Telrad (never owned a Telrad!), a dew shield (nice dew shield material too!), two dovetails, a Losmandy type dovetail and a Vixen long dovetail from Scopestuff, both on opposite sides of the OTA. Now if I ever want to upgrade to a imaging rig, this will be a boon for me. The focuser took a little bit of getting used to though since I have always been a rack and pinion kinda guy. Focusing was okay, if kind of stiff. I wonder if it needs lubricating. However once you get it close, it only requires minor tweaks to get it focused. And surprise surprise...I detected no image shift, one of the quirks of SCT's as focusing is achieved by moving the primary mirror back and forth on a focusing track.
In the field
Now comes the acid test, the star test. The scope, on the Vixen Porta mount is only slightly heavier than the C6 on the Porta, so it is easily carried in one hand, freeing my other hand for accessories such as my camping chair, etc. etc. Definately a plus when it comes to grab and go stargazing. Optics are also surprisingly good, with perfect collimation. The airy disc are reminiscent of refractor views and showed no asymmetry whatsoever when defocused on both sides of the focus. No doughnut holes and no spiking on stars like in my newts. Also the views appeared sharp to the edges with all my ep's, even the inexpensive ones such as the Orion Explorer II ep's. The views of the moon were nice and color free. I did not detect any chromatic aberration if there were some to be detected. I have never seen the craters stand out like that at high magnification. As mentioned earlier, this is most likely the product of superior contrast!!!!!
Views of DSO's were very nice. My premium ep's really shone in this scope for some strange reason. The optical quality of these ep's were very noticeable in the C8. I used all three ep's of my premium ep's, the 24.5mm Meade SWA, 13T6 TV Nagler and 6mm TV Radian. Even my 20mm and 15mm Orion Expanse ep's performed wonderfully. The few DSO's I tested the scope on included some summer objects, but mostly fall objects. Bear in mind that testing was done in the presence of a almost 80% illuminated waning moon. It was noted that contrast was excellent in this scope, better than in my newtonians, probably a product of good baffling and the extended dew shield that came with the scope. Here are my notes of the views:
- M57 (Ring Nebula, Lyra): Wonderfully framed at 83x in my 24.5mm (my lowest powered ep..the equivalent of a 32mm Plossl with its 68 degree FOV). Ring was bright and distinct at this magnification. Bumping up the magnification to 102x (20mm Expanse) gave a even better view. Also viewed at 156x (13T6) and 338x (6mm Radian) without loss of brightness. Best views at 156x with the Celestron/Baader OIII (yes finally the filter is useful...somehow better than the NPB). Equal in brightness from the burbs to the 10" (will have to do a confirmation...going by memory).
- M27 (Dumbbell Nebula, Vulpecula): Nicely framed in the 24.5mm at 83x with the OIII. Viewed at all magnifications, as detailed above. Best views in the 20mm Expanse at 102x with the OIII. Big and bright with some detail discernible, like the variation in brightness between the northern and southern portions.
- NGC6826 (Blinking Planetary, Cygnus): As above. Best views for wide field in the 20mm Expanse at 102x with the OIII. Awesome high powered views at 156x (13T6) with the OIII. Preferred the native view sans the OIII at 338x with the 6mm Radian. The planetary was a little whitish green disk even at the lowest magnification, which was of course not as low as on my wide field reflectors.
- M13 (Hercules globular, Hercules): Getting a little bit low now and was down in the light pollution swamp but nevertheless resolved with averted vision to the core at 156x (13T6) and at 338x with the 6mm Radian. View would have been markedly better had the globular been higher. My preferred magnification was 156x as it was a good mix of resolution and brightness.
- M92 (Hercules): Same for this globular, although the resolution was not all the way. Also in light pollution swamp. I am confident there will be more resolution had this been higher. Best views again at 156x.
- M15 (Pegasus): Not fully resolved even at 338x with the 6mm Radian. M15 has a very tight core, reminiscent of 47 Tucana in the south. Nevertheless very beautiful with it myriad of resolved sparkling suns at its periphery, and a few winking in and out across its dense core. This globular takes magnification better than M13 and M92, probably due to its more compact nature.
- M2 (Aquarius): Very nicely resolved even at 156x (13T6 Nagler). Gorgeous at 336x (6mm Radian). My favourite views of this globular was at 156x though as this resolved the globular almost fully and gave a good balance of brightness, with the globular framed by a dark background. The best globular viewed this night, besting M13 probably due to its elevation in the sky.
So yes the used C8 OTA is a winner in my book. It came with everything I needed, including Vixen and Losmandy rails, a Telrad (which is currently not useable due to its location on the OTA), a 1.25" Celestron visual back, a home made plastic case for the OTA (with foam inserts cool!!!!), as well as a flexible yet sturdy dew shield that fastens with velcro. When I agreed to purchase the scope, I was worried that I might have to get other extra's to properly use the scope. I might still need a visual and photographic reducer at some stage (damn the SCT specific ones are expensive. The cheapest new reducer I found was from Agena Astro. They were "Antares" branded and they cost $89 for a f/6.3. The Meade and Celestron branded ones are more expensive. Meade also carried a f/3.3 reducer but those cost over $100 bucks!), but as it stands, the scope is well equipped to be used out of the box. The seller also mentioned smudgy corrector plate and a small dent on the side of the OTA, which was not all that noticeable. I can foresee myself getting back into visual astronomy with this scope.
As promised, in order to make sure my memory was not playing tricks on me, I had the 10" GS f/5 dob out in the field for testing last night, as my memory of what objects look like in the C8 was still fresh in my memory from two nights ago. All class of objects looked at did not have significant additional detail on them in the 10" (I kind of expected this but just wanted to be sure). Brightness factor, if at all visible was small. I guess side by side you probably could detect a slight increase in brightness in the 10". This was however not apparent to me tonight. As an example, both the Ring and Dumbbell looked identical in brightness in both scopes at similar magnifications. Any details I could see in the 10", I could also detect in the C8. I found that I could push the C8 higher in magnification than the dob, indicating that the C8 was very well collimated. On globulars, both scopes showed a similar level of detail. As with the planetaries, whatever resolution I got in the 10" dob, a similar level of resolution was seen in the C8. It was noted, however that somehow stars seemed sharper and popped out more in the C8. As mentioned previously the C8 is very well baffled and the background was a nice dark canvas. Now my dob is flocked too, but still the background and contrast was inferior in comparison to the C8. So will the C8 be able to fill dobbie's big 10" shoes? I think it most certainly will, and with extra room to spare on my car boot!