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Life with the Dobsonian telescope.

I had finally decided to quit living the life of a vicarious astronomer through books, magazines and the internet. So, the first thing I did was start supplementing my HST and NASA web page visits with visits to equipment sites. If I ever thought that I was overwhelmed by the availability of astronomy info available on the net, I was almost as over come by the shear number of equipment sites that I could link to. Manufacturers, distributors, and hobbyist builder sites by the hundreds.

But, what inspired me to compose this was that almost no one really went as far as to say what it was like to use a particular telescope. User related info on the Dobsonian telescope, as popular as it is, seemed curiously difficult to find. I was able to find a little here and a little there, but nothing that particularly satisfied my curiosity.

What I ended up doing was asking a lot of questions to the owners of different telescopes. In the end, like more and more first time telescope buyers are doing, I bought a Dob. To be more specific it's a 10" Meade Starfinder Deluxe. It wasn't exactly my dream scope, but it appeared to be just the ticket for my introduction to deep sky viewing.

I had originally planed to buy the dob's equatorial mounted brother, though at the last minute opted out. Partly because of the money, but mostly because how easy the Dob is to set up and take down. Having a growing family, working full time, and going to school part time puts a big demand on my time. So there was quite an allure to the economy of the dob's setup.

There are limitations to the telescope's ergonomics, due to it being an economical model. However, it is very simple to use and the optics are superb. Just grab the tube and push it to where you want it to be. It's that easy.

Even though there are differences from one Dob telescope to the next, there are a lot of basic similarities. The Meade Starfinder does seem to be a good middle of the road scope to base an evaluation.

To make the info a bit more accessible, I'm going to break the narrative down into more digestible chunks:

Ordering From a Distributor
Some Assembly Required
The Dobsonian Mount
The Optical Tube and Accoutrements
The Mirror Cell
Looking at the Universe Upside-Down
A Limit to the Magnification
Looking at the Moon
Chasing Planets
The Awe of the Deep Sky
Some Worthwhile Additions

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Ordering From a Distributor…..
Once I had made my mind up to buy the Meade Starfinder, I then had to decide which distributor to buy it from. Enter the next profusion of choices to wade through. Did you know that there are actually web sites that feature reviews of equipment distributors? That's just an indicator of exactly how many equipment dealers there are now offering nationwide service. Luckily, I had devoured Phil Harrington’s book Star Ware early on, and was very impressed with the fact that Pocono Mountain Optics had lent some equipment to the ace reviewer. But I did want to make sure that I had covered all bases. So, from here I did what any good shopper would do, especially one as obsessed with the subject as I was at this point. I started checking the price and availability of the Starfinder at each of the more reputable distributors. I soon discovered that they all offer the same factory direct drop ship method at about the same price. This means that you place the order with the distributor, they route the order directly to the manufacturer, and once the new telescope is built, the factory then ships it directly to you. This all means that you have to wait 30-60 days for the factory to churn one out, but it is the absolute best price.

Some Assembly Required…..
After only 30 days, my new telescope arrived. In three boxes! The largest of the boxes contained the sonotube fitted with the spider and secondary mirror. The primary mirror cell was completely assembled and stowed in a styrofoam package separate from the tube. Box number two held all of the pressboard pieces that make up the mount. The only parts of the mount that were attached were the teflon pads (though they look an awful lot more like nylon than teflon). The third box had the focuser, finderscope, and eyepieces. Though the instructions were vague, they were sufficient. All in all, it took about three hours to assemble the entire telescope. This of course didn't include collimation, which took another hour. A little word to the wise here, the instructions say the new scope shouldn't need collimating. Nothing could have been farther from the truth. I had to adjust everything. Overall though, it wasn't too bad. The scopes mirror is very nice and the collimation went by the book (which was a blessing since I was new at it and was working straight from the book). Just make sure that you have a good set of screwdrivers and the best collimation tool you can afford (I recommend the full Tectron tool set along with the book). The only thing that's left to do now is take it outside and line up the finderscope.

The Dobsonian Mount…..
The Dobsonian style mount is nothing more than a Lazy Susan with an altitude axis. The telescope's tube has what's called an altitude bearing fastened on either side. They're strategically placed as near as possible to the optical tubes center of gravity. You just gently place the fully outfitted optical tube assembly into the half circle cradle so that it's resting on the altitude bearings. I know, it sounds so simple that it couldn't possibly work. Nevertheless it does indeed work, and well at that. The whole object of the game is to work on the mount's bushings until they are buttery smooth, but not so smooth that the telescope won't hold its position when you remove your hand. If balance becomes a problem when you add heavy eyepieces or accessories you can add counterweights to the lower portion of the optical tube assembly. Nothing fancy is needed, something as simplistic as fishing weights will do, or if you're a perfectionist, you can purchase sliding weights from numerous sources.

The Optical Tube and Accoutrements…..
The first time I saw a large reflector that used a sonotube, I couldn't help but think that it looked like some kind of overgrown and painted toilet paper tube. Oh how disappointing, it looked hideous. I could barely believe that someone would actually charge hundreds of dollars for a telescope fashioned from such a thing. There was just no way I was going to buy that. How things change. I came to learn that it is fairly durable, but most importantly, it's suppose to adjust to the outside temperatures better than aluminum or fiberglass. All of its cosmetic woes aside, it works well and after a while it kind of grew on me (but it does still look like a toilet paper tube!). The exterior of the sonotube has a painted finish that aides in it water resistance. The tubes interior is painted flat black to reduce the effects of local light. The finderscope and focuser mount directly to the tube wall with simple hardware. I won't spend a lot of time picking on the fact that the finderscope is undersized and focuser isn't as smooth as I would ultimately like it. If I was going to demand perfection, I would have bought a telescope that cost much more than the Starfinder. I will say that both function well for their intended purpose, and can be easily replaced if you feel the need. (I should note that a 1x pointing device, such as a Telrad, is worth its weight in gold to hunt down faint objects. You can purchase one for under $50 and is easily attached to the sonotube with the double sided tape that is supplied with it.)

The Mirror Cell…..
The sonotube's looks, took second place only to my reservation about a mirror cell made from pressboard. I've heard horror stories about the lack of quality control at all three of the major mass production telescope manufacturers from years gone by. The one that sticks in my mind is of mirror aberrations caused by a poorly mounted mirror on pressboard. To all the companies credit, I haven't actually met anyone who has had a real problem related to the mirror, or anything else for that matter. Personally, my mirror looks great, the cell itself is sturdy. I wouldn't hesitate at recommending it to anyone. Though not being as well ventilated as an aluminum cell does hamper cooling.

Looking at the Universe Upside-Down…..
Part of life with any telescope is having to cope with looking at an inverted image. It's no real problem and is easy to master. The one peculiarity that the Dob seems to compound is the diagonal trek that an object makes across the mirror as you move the scope from side to side or up and down. I attribute this phenomenon to two things, first the altitude-azimuth style of the Dob mount doesn't allow for the celestial equatorial tracking that the more sophisticated mounts provide. Second, the focuser is mounted at about 45 degrees or so off square, which I believe helps add to the perception of diagonal movement, even if it's not directly responsible.

A Limit to the Magnification…..
The lack of a motorized equatorial mount definitely limits the magnification that you can use. Once you get around 200x you spend most of your time adjusting the mount, with little time left to focus. The limit to magnification with this scope is somewhere between 200x and 300x, though anything above 250x would really be pushing it, or I should say, you'll really be pushing the scope to keep up with the objects whizzing by. Even though this may sound quite disheartening to someone without much experience, there is a flip side. You simply don't need more than 200x to enjoy most of what a 10" reflector can show you.

Looking at the Moon…..
A light bucket like the Starfinder presents you with an image of the moon so bright that you won't be able to view it without a Moon filter or some other light filtering device. Just screw a sufficiently dark filter into the underside of the eyepiece and hold on. Even though I had seen the Moon plenty through a pair of binoculars, it didn't prepare me for the vistas that were opened up to me.

Chasing Planets…..
While the Dob has many strong points, planetary viewing is not one of them. Don't get me wrong, you can see all the planets with it, just not with enough magnification to observe fine detail. The rings of Saturn, bands of Jupiter, and slight geographical detail of Mars are obtainable with little effort. However, if the planets are what your after, then buy a telescope with a motorized equatorial mount.

The Awe of the Deep Sky…..
Here is where the Dob really shines. The larger mirror that you were able to afford due to the dollar savings of the simple mount design will reign in the faint fuzzies and make all that planet chasing worth while. The 10" Starfinder has been able to show me nebulae, galaxies, and star clusters in amazing detail. Don't expect the detail or vivid colors you see in magazines, they only come from long exposure photography. But do expect to see all the Messier objects plus countless others in sufficient detail to still be positively breathtaking. Even though the faint fuzzies are in fact faint and fuzzy, being able to see them in real time gives one a feeling of awe that you can't get looking at a photograph

Some Worthwhile Additions…..
There's a couple of couple of items that the Starfinder (and other economy scopes), can really benefit from. First, is a larger finderscope. If your serious about hunting down deep sky objects a finder of around 50mm or more is almost essential, especially if you plan on venturing past the Messier catalogue. I highly recommend a combination of the Meade 8x50 and the Telrad finder. The Telrad will quickly you to get into the general area of the desired object, then you can use the 8x50 to zero in on it. If you plan on trying your hand at a Messier Marathon I would give it serious consideration.
Second on the list is a better quality focuser. I'm not going to rag on the factory issued rack and pinion unit (it's part of the reason why the scope is affordable, and it's more than good enough to be serviceable), but a high quality Crayford focuser makes achieving a well resolved image much easier. I installed a JMI NGF-DX3 on my 10" Starfinder, and it looks and works great! If you are going to buy one, make sure you order it direct from JMI so you can get the proper mounting base radius (10" and smaller Starfinders should use a 5" radius). You'll need a mounting plate to reinforce the Sonotube, and either a 2.5" extension tube or the special length draw tube that they offer for the Starfinder. As a side note, I had a lot of questions when I was putting together my order, and not only did the nice folks at JMI talk to me like they had known me for years, but were VERY helpful.