The One That DIDN’T Get Away

The Original Celestron C6

The original Celestron C6 was a Polaris-mounted 6" f/5 Newtonian.

A few months ago, I wrote about the Celestron C6 Newtonian reflector that was produced by Vixen back in the 1980’s. It was the third of four “classic black Celestrons” that I remembered from when I was a kid, and unique in that it was a wide-field telescope in contrast to the Firstscope 80, C4.5 and C8. While my early attempts to acquire one were unsuccessful, a few months ago I did win an eBay auction for a C6 optical tube assembly.

It arrived without a finder or a front endcap, but I’ve got a friend who may part with her original 6×30 finder from her SP-C6, and heavy-duty shower cap functions as an effective tube cover. There are a few small nicks in the paint, and two small holes where a Telrad base was mounted, but a little touch-up will fix those tiny cosmetic issues.

I’ve had a lot of fun tinkering with this scope (mostly in the garage and the driveway so far), and I’ve learned a few things.

The first thing I’ve learned is that the Polaris mount is more than adequate for this telescope. I really can’t think of a reason why Celestron switched this scope from the original Polaris to the much-heavier Super Polaris mount, other than increased profits in a more astrophotography-ready package. I’m thinking the astrophotography-profit angle here because there were optional dual-axis drive motors available for the Super Polaris, they could charge more for the heavier mount itself, and the 6″ f/5 OTA has a constant-distance “sled” focuser with a generously-sized secondary mirror which would appeal to shutterbugs of the day. At any rate, for visual use, the Polaris mount is simply wonderful. Even without a  second counterweight and the scope being woefully out of balance, when I lock it down, it doesn’t wiggle. At all.

It's easy to drop the rear cell from the C6, just like it is for the C4.5 -- once you know how. That makes it easy to center-spot the primary, which is necessary for collimation.

Another thing I’ve learned is that Vixen really did a great job on their Newtonians. Just like the C4.5, the C6 primary and secondary mirrors are easy to adjust. In fact, this scope practically invites collimation! It was a simple matter to drop the back half of the cell and center-spot the scope, and once I had a proper reference, the scope was collimated in a matter of minutes. The only plastic on the scope is the single focuser knob, and the rack and pinion gears of the “sled” style focuser. I’m told that those plastic gears are the only real points of potential wear and failure on this scope; everything else in the focuser is aluminum. Oh, if they just used brass for those two little parts instead of plastic! If I ever have problems with the plastic gears in the focuser, that’s what I’ll use to replace them.

I also learned why they don’t make threaded declination shafts anymore. These were super-cool-looking on the giant yellow Byers mounts that graced the 1960s and 1970s Questar-12 ads in Sky & Telescope. Perhaps in an attempt to enhance the precision feel of the original Polaris mount, the declination shaft is, in fact, a single length of 16mmx2.0 threaded rod. It does look great, and makes it easy to fine-tune the counterweight position. However, it also makes it a major pain to move the counterweight any significant distance, and taking the counterweight off the declination shaft for portability is more trouble than it’s worth. For the C4.5 OTA, there’s only one counterweight and it’s not a big deal to move the entire thing — mount and scope —  around because it’s so lightweight. I’m thinking the second counterweight is going to be around 8 pounds to accommodate the larger C6 OTA, so that’s going to make the overall setup noticeably heavier. It’ll be easier to remove the entire declination shaft for transport, should it become necessary.

As a side note, what you see in the picture is indeed a 25mm Plossl of the old Celestron “silvertop” variety. I’ve collected several Celestron silvertop Plossls over the decades, and all but one are red-lettered Vixen models of the same vintage as this scope. When I get that second counterweight made to allow for less dangerous use of the C6 on this mount, I plan to use the silvertops exclusively; in my limited testing so far, the vintage Plossls have been surprisingly good. A 16mm Nagler Type 5 might sneak onto the focuser once in a while, though…

Classic Black Celestrons

Over the past several years, I’ve acquired a pair of Celestron telescopes from the late ’80s and early ’90s, along with some parts and time to “restore” them. Now I’m about ready to use them in earnest, and I think they will be a great pair for outreach events. Let me tell you about them.

Celestron C4.5

Purchased for $75 from Craigslist -- several years ago.

The first telescope of the pair is a Celestron C4.5. This is a Vixen-made 4.5″ f/8 Newtonian on the wonderful Polaris German equatorial mount. I purchased this instrument several years ago from a lady on Craigslist, who didn’t know much about it except that she wanted to get it out of her basement. It needed a lot of cleanup, and I left it stored in pieces after the last round of work on the scope. Recently, though, I put it back together and am now patiently waiting for some good weather to really put this instrument through it’s paces — everything is top-notch on this scope, except for the run-of-the-mill 5×24 finder. It didn’t come with a clock drive, and the original units are long gone from production and hard to come by on the used market. Fortunately, the modern Celestron/Logic drive will bolt right onto the mount and provide RA tracking with just a 9v battery; it’s a no-brainer at $35 and it will arrive soon from Hands On Optics. Until then, the slow-motion knob works well for manual tracking. I took a look at some nice sunspots just today with the included 25mm Celestron Orthoscopic eyepiece and a 5″ Thousand Oaks filter I already had for the old Nexstar 5 (another story for another time).

Celestron Classic 8

Celestron Classic 8 from 1992. Bought used at a swap meet in 2010.

The second telescope of the pair is a 1992 Celestron Classic 8 on the heavy-duty tripod of the day (this was purchased at a swap meet last spring and so I know more about it’s history). I power the AC clock drive from a jump-starter battery pack and a small inverter I had laying around in the garage, and the tracking is very good. Last year I used it a few times for sidewalk astronomy at Bayshore Town Center and it worked out very well. In fact, with the tracking I found myself with more ability to interact with people in conversation while they looked through the telescope, because I didn’t constantly have to interrupt by asking “is it still there?” or moving them away to re-center the object for them. We never have a problem with dew at Bayshore, probably becuase of all the heat from the sidewalk, road, and nearby buildings, so I never had to use a dew shield. Optically, the scope seems to be a winner as well, so much so that I tried using it in the backyard a few times last summer. That 6×30 straight-through finder was a pain to use, though, and I thought to myself I”ll need get a different finder for deep-sky work. Back in the grass, the dew situation was much worse as well. A simple $25 dew shield will help with that (coming in with the Logic drive from Hands On Optics). As for the finder, I managed to acquire the Vixen-made Celestron 8×50 Polaris finder at last month’s swap meet (one year after getting the scope itself), which has now replaced the original 6×30 finder. I’m thinking that 6×30 finder might make it’s way onto the C4.5, but that’s a project for another day.

Why do I care about these telescopes? What’s the fascination? Well, these scopes represented modern chic in telescopes “back in the day.” I graduated high school in 1989 so both of these instruments stand out in my memory, and appeal to me greatly. Maybe this is my version of a mid-life crisis…I don’t know. But they are a LOT cheaper than a sports car! The fact I was able to rescue them for very reasonable prices (the C4.5 was almost free) and put them into service again is just a wonderful feeling. Using them for outreach, they will introduce hundreds of people to the wonders of astronomy each year. Using them under the dark skies of Harrington Beach, they will take me back to my youth. Simple and effective telescopes such as these have no expiration date.

I prefer star hopping with small scopes, especially in outreach situations, but tracking will allow me to run both scopes at the same time. The dual “classic black” Celestrons should be an awesome pair in this regard. Plus, I think they look really cool and will attract attention on the sidewalk. We’ll see next month when the sidewalk astronomy season begins!