A tale of two scopes: My obsession with small refractors

Pre-amble

"Cometron CO60E in alt az mode"

What is the allure of small refractors? With their limited aperture, views of most objects are dim, in comparison to larger reflectors. Maybe its the history, the romance. Galileo never had a scope as good as some of the most basic model we have today, yet he discovered Jupiter and its dancing moons! Trying to rekindle the first time, the first views of objects would probably rank highly too. I have been an avid fan of small refractors for as long as I can remember. I have been chasing that elusive "keeper" scope for quite a while now. I remember lusting after these small scopes ever since I obtained my first "real" scope, a humble Celestron CO40 achromatic refractor back in the early 80's. While most people would have probably left the hobby after looking through such a small scope, I was not one of them. Maybe it was my innate curiousity to push the boundaries, to discover what I could see with such a small aperture. It is probably that same curiousity that prompted me to take up my profession, as a research scientist. That childhood spark is still there!

I have gone through several small scopes in the 60mm class since returning to the hobby in 2001. Some notables include the dastardly Yosco stopped down 60mm Japanaese scope (everything about this scope screamed vintage Japanese, except for its less than stellar stoppered down single element optics), the Kasai 60mm Orange ST scope on spindly tripod (Never should have let this one go. One of a kind and probably made by the same good people who made the Celestron Cometron scopes), a fantastic grey tubed Celestron Cometron CO60 (Another throwback to my 80's roots, this was the bigger brother of my CO40. Came with the same shaky mount and 5x24 stopped down finder), yet another amazing blue metal tubed Meade 60mm refractor (This one was actually a very good performer, and the mount was surprisingly steady) and the tank-like Orion 60mm ST OmniVista on a makeshift alt-az slow motion mount. My last two acquisitions might yet be the ultimate 60mm class scopes. Introducting the Burgess BackPacker 65ED optical tube, and my $15 (yup you read right...the person was going to throw the scope out!) Celestron Cometron CO60E.

Burgess BackPacker 65ED Optical Tube Assembly (OTA)

"Burgess Backpacker 65ED"

Chanced on this scope while randomly browsing the Astromart web site, like I always do on a daily basis. Its funny how I never heard of this scope until now, seeing how I am very much aware of Bill Burgess and his "experimental optics and scope". The story with this scope is that Bill was trying to produce a small short focal length scope that had color free optics by using ED optics. He ordered a batch of about a 100, only to discover that the two elements did not sit properly together, and with the non collimatable lens cell, the optics were never going to focus down to a point source. To cut his losses, he sold off the optics, the OTA body and the dew-shield for a song $25. In the know amateur's got wind of this and snapped them up and began experimenting with this "work in progress". Being ever so resourceful, some of these said amateur's got the scope to work. The instructions are still available here.

"Burgess 65ED on Orion Paragon HD-F2 photo tripod with slow motion control head"

Next up was finding a focuser for the OTA. Again Bill came to the rescue and made available a rack and pinion focuser for the said scope. And the rest is history. My copy of this scope came with a respectable single speed GSO Crayford focuser. Being an "experimental" scope, the last owner wanted to make sure I knew its limitations. Being in the Bay Area,, he drove the scope down and we met at Orion Telescopes Store in Cupertino. This scope came with the pre-drilled lens cell for collimation and an attached mounting shoe, much like those found on the early Orion 80ST OTAs. Seeing how the Crayford is not standard fare, the OTA is back heavy and tends to want to gravitate that way when observing. I tried screwing on a short Orion dovetail, but due to the distance between the holes, I was not able to get it to sit properly. Due to the weight of the scope, the OTA would always find a way to rotate out of the dovetail. My solution to this was to mount the OTA on one of those slow motion devices for photo tripods. Surprisingly this worked really well. I found I could use the scope quite comfortably on my Orion HD F2 photo tripod this way. This will make for an excellent throw in the booth of the car type observing sessions.

Optically this scope does one up on two element achromatic refractors as there is less false color on brighter objects. Still in comparison to say a newtonian reflector, the views are markedly warmer. I also found that the scope does not like doing higher powers. There is some flaring off to the side of bright objects. My guess is that collimation is still slightly off and needs to be touched up a bit. Still all in all, the views  I got from this "mere" 65mm scope were on par with my 70mm Celestron Travelscope ST. Where scopes such as these excel are under dark skies and with wide angle eyepieces. Testing the scope from my orange zone observing site in Saratoga Gap, with the 24mm Meade SWA eyepiece, and the 13T6 Nagler, I had a grand time touring the star spangled fields of Sagittarius-Scorpius. The views were markedly brighter than what I remembered in the Japanese made Orion OmniVista. In fact this scope behaved more like my old 80mm Orion ST! So I guess the take home message is that if you stay with medium and low powered eyepieces, this scope can and will deliver. Now time to find a way to mount it for CCD imaging!

Celestron Cometron CO60E

"Cometron CO60E on Vixen Polaris Mount"

Now this is the definition of an excellent Japanese made starter scope. After a couple of nights of testing, I can safely say my quest for the perfect 60mm long focal length scope has ended!
Found this beauty for a song ($15) on Craigslist. The scope was about to be chucked out so I had to go rescue it. Comes with a gorgeous Vixen Polaris Mount (the only EQ mount back in the day that could do double duty as an EQ and an alt-az mount due to its design) and rare as hens teeth 60mm adjustable tube rings! The scope only came with one eyepiece, a nice 10mm Celestron Kellner, a sweet metal bodied 0.965" star diagonal (not like the plastic ones that came with the alt-az Cometron models) and those stoppered down 5x24mm plastic body finders (but with a metal bracket). What I do love about this scope is its longer focal length (910mm versus 800mm on the alt az models) and its fully coated optics (as opposed to the coated optics on the alt-az models). The vintage of this scope is similar to my first scope, the orange tubed Celestron Cometron CO40 (early/mid 80's in time for Halley Comet). I remember seeing adverts by Lumicon for this scope in Astronomy Magazine's 80's issues, touting these scopes as the perfect scope for capturing Comet Halley on film! I would say that would be stretching the truth a little, unless you were doing wide field piggyback astrophotography with a motor drive.

"Vixen Polaris Mount, a hybrid alt-az, EQ mount"

To say that this scope is over-mounted would be an understatement. The mount that comes with this scope is one of the most sought after vintage Vixen mounts, the Vixen Polaris Mount (they are no longer made mind you!). Back in the day you could get several OTA bundled with this spiffy mount. Orion Telescopes used to sell the Vixen/Celestron C6 f/5 (newtonian reflector with the sliding focuser, which I also happen to own!), and a CO90 (90mm long focal length achromatic refractor). Mount a dinky little achromatic 60mm refractor, even with a long focal length, and you got yourself a rock steady setup! What makes this even sweeter is that due to the design of the mount, this can do double duty as a non motorized equatorial mount, or a rock steady alt-az mount. The only thing I dislike about this is the screw on balance weights and the threaded shaft for the counterweights (you can only use the proprietary counterweights on this). Some have solved this by threading on the standard counterweight shaft from its younger brother, the Vixen Super Polaris mount.

"Focuser on the Cometron CO60 OTA"

Optically, I expected great things from the OTA. Based on my experience with small long focal length refractors, this scope, with its even longer focal length (910 mm versus 800 mm on the standard alt az model), color correction would be pretty good. I was right. The scope threw up gorgeously sharp and almost color free views of Venus, an extremely difficult test for two element achromatic lenses.  The king of planets Jupiter showed subtle banding pattern (not just the two expected equatorial bands) and Cassini's Division was plain to see in the scope. And all these using just that one 10mm Celestron Kellner eyepiece which gave a magnification of about 91x. I even snuck in a peek at M57 the Ring Nebula, and while not nearly as bright as the views in my larger scopes, the celestial doughnut was definitely visible. The dark hollow was visible, with averted vision.

I had another chance to test the optics out with a new/old eyepiece I purchased just for this scope. It is a  80's "Halloween" 25mm Celestron Plossl that looks to be in a 1.25" size, but with a 0.965" silver barrel. This eyepiece gives a magnification of about 35x, just the right magnification for wide angle views, with a little bit of power. Due to the size of the barrel, and its long eye relief, I found the eyepiece very comfortable to use with my eye glasses on, something which is usually not possible with 0.965" barreled eyepieces. I scanned the southern milky way with this combination and it was a revelation. Of course views are not as bright or detailed as in my larger scopes. But the views of objects such as M8, M20, M17, M22 and even M28 were nice. From my red zone skies, the globulars were still unresolved globs of light. However the larger emission nebulae threw up a surprising amount of detail from my skies. I will be taking this scope to a darker site at some point because I know what a 60mm scope is capable of after using my now sold Meade blue tubed 60mm. Stay tuned for more reports from both scopes!!!!!

"Scope came with a very nice metal bodied star diagonal and 10mm Celestron Kellner"