Monday, January 17, 2011

Back to Bushnell

When I was 8 or 9 years old, I remember having an interest in astronomy and so my parents bought me a department store telescope, one christmas. While it wasn't one of the dreaded Tasco 'scopes, it was only a slight improvement: a Bushnell. It was refractor a couple of feet long with a two-inch plastic lens, two 0.85" eyepieces (15mm and 5mm) with astonishingly small apertures, a couple of plastic barlows and a star diagonal. To its credit, it did have a rudimentary viewfinder and extendable wooden legs for the altitude-azimuth platform. Unfortunately, aside from the Moon, I wasn't really able to see much of anything, despite many nights of attempts. I do remember one very bright star which I used to look at and watch how it would shimmer and change colour while close to the horizon (Based on the year and the view from my window, Stellarium suggests that this was Sirius). Given my inability to get much out of the thing, I pretty much abandoned it and let it sit idle in my room waiting for the night or two a year when my curiosity would grab at me and I would haul it out again.

I know now that such a scope is not really a very useful piece of equipment. But I have always wondered: was my inability to see anything with it a failure in my equipment or a failure in my understanding? Over the holidays, I was rummaging around in my parents' basement when I saw the telescope sitting there in a box. I couldn't help but haul it out to try and answer my own question. And I had a perfect set of targets to try the thing out on: Jupiter was up early, and later I could take a look at the Pleiades and the Orion Nebula.  Or rather, I could try and see whether or not my newfound knowledge could give some use to the old thing. Methodically, I took the 'scope out of the box, cleaned its parts (as I had never done before) and put it together before taking it out into a crisp Eastern Ontario night.

It's interesting what a difference 20 years makes - parts that I had recalled to be glass were actually plastic. The 0.85" eyepieces had such tiny apertures that cleaning them without tools was next to impossible and  looking through them was a chore. Once I got outside, even the widest of the eyepieces, the 15mm, produced such a narrow field of view that it was difficult to locate objects seen through the finder scope. The 5-mm and the two barlows? Forget about them.

As well, I had forgotten what a chore it is to track an object with an alt-az mount that you need to touch directly to move; the vibrations and stickiness of the mount were always the worst part, and this night was no different. Tighten the main nuts too much and the scope won't move until you've applied enough force to jerk it halfway across the sky. Tighten the nuts too little and gravity pulls your view continuously until the scope is in a somewhat vertical position. What you end up doing is compromising on the tightness and gently tugging on the scope until the object you want to look at is biased out of the field of view. Then you release the instrument and hope that when it snaps back it will catch before the object drifts out of the field of view on the other side.

Even with this annoyance, it was possible to make some observations. Jupiter was the easiest target and I slewed to it first. Though the 15-mm, it was a dim circle of light. I adjusted the focus as best I could and waited for the atmospheric turbulence to sort itself out. Lo and behold, some features became apparent. There was a hint at banding. The Galilean moons were just barely visible, but they were there. Emboldened by this success, I tried the 5-mm eyepiece. It took some doing, but finally I had Jupiter in the field. Unfortunately, here the view was murky and unsatisfying. The same was true with either the 2.3x or 3x barlows, and with Jupiter continuously racing from the field (necessitating the lengthy process of finding it all over again) I gave up on this object.

Next, I headed over to the orion nebula and was slightly impressed: I might have detected the merest traces of wispy gas. But it was so faint that it could have been residual dust within the telescope. As for the Pleiades, well, a star cluster always looks good, though the individual members appeared much less distinct than in other scopes I have used.

So what conclusions can I draw? Well, it's not looking too good for the scope. Using the knowledge that I have gained, I was able to get more out of the instrument, but not much. Worse, I worry that by knowing what I was looking for, I might have biased what I saw as Comas-SolĂ  and Schiaparelli have done before me. Recall those bands on Jupiter that I thought I could see: was I seeing them now because I knew they were there? Or would I have come to that conclusion without prior knowledge? It's hard to say. As for the higher magnifications, they were useless - knowledge or no knowledge. Similarly, I was unimpressed with my other two targets. For both, I know that I can get a more vivid view through my 9x63 binoculars (a great way to start when looking at the sky, I might add, and only about $200 for a fancy pair).

It's interesting that my Stellarium research shows that Jupiter would have been one of the brighter objects in the bit of sky I could see from my window in the early 1990s and would have been reasonably close to Sirius:

Did I ever train my telescope on this object? Perhaps I did - I can recall trying to look at all of the brighter objects I could see. But it's likely that without the knowledge that it was a planet and given its fuzziness, I might have tried to focus it down into a point. I certainly don't remember seeing a disc. There's no way to know for sure.

I should point out that my parents are blameless in my childhood folly. They didn't know any better, and the box certainly seemed to assuage any fears they might have had. Then as now, it was covered by images of galaxies, planets, moons, nebulas - you name it. And the magnification rating! 435 times - why, it would be just like seeing these worlds up close! Alternate sources of information were relatively hard to come by. There was no real internet in the late 1980s, certainly not in the way we know it today, and I would be doubtful that the clerk at Sears would have been any more knowledgable. St. John's, one of the foggiest, cloudiest parts of the world was not known as a great clearinghouse for optical instruments.

Eventually I would do better. The RASC course that I took over the winter of 1997/1998 showed me what was possible. I still remember that first impressive view of Saturn through a 6" Celestron Schmidt Cassegrain, as perched on the hill in Pippy Park. When it came time to look for a telescope again in my second year of undergrad, I was prepared and selected a 5" Sky Watcher Newtonian with a parabolic reflector. Over the years I remember being very impressed with what I could see with what was still a relatively cheap (the Sky Watcher ran $400) instrument. For instance, I held a cheap webcam up to the lens for this look of the moon through my 19th floor window in downtown Toronto taken in February of 2002:

Once you have a decent instrument, it's the rest of the equipment, the expertise and the location that makes the difference. Here's the same telescope in January of 2007 with a Pentax DSLR in Tucson, AZ:

At the end of the day, I can't say that my ownership of the Bushnell Telescope really increased my interest in Astronomy, though it did afford good views of the moon. If that's the only thing you want to look at, you will do just fine with one of these. But for anything else, you need a tool that matches your interest and knowledge.

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