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Astronomy by Michelle

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Astronomy Product Reviews by Michelle Stone
Obsession 18" F4.5 Compact Portable Reflector


Obsession Telescopes - Lake Mills, WI 53551 USA
(Fax line also)

The big decision:

I looked long and hard to find everyone that made a scope in this aperture range. I wanted a large aperture reflector so that I could look at deep sky objects such as galaxies and dim planetaries. My requirements demanded that I pack as much light collection as possible into a package that I could move and set up myself. I also take great delight in the esthetic qualities that make an instrument a pleasure to use. I wanted an instrument that was elegant, simple to set up, easy to use, and had superb performance.

I believe that many offerings today have fine optics. Mirrors in these "commercially available" scopes all come from fine companies. The big differences in these products are in everything else that makes up an instrument.

I have to admit that Obsession's web page had a great deal to do with the decision I made. The other companies didn't go far enough in describing their products nor did they really enthuse me. I'm not saying that a good sales job makes a good product... I'm just saying that much of the information I needed to help me make the decision was there.

I originally planned on getting the 15" scope. I thought about it however and knew that it wouldn't be long until I would hunger for larger aperature. I might as well spring for the largest that I thought I could handle.? After checking with some friends, I believed that the 18" fit the bill.

Placing the order

I sent Dave Kriege (the owner of Obsession Telescopes) an order for the scope along with a 50% deposit. All of the manufacturers require a significant deposit at order time. I ordered the 18" F4.5 scope with an enhanced coated Nova mirror, a shroud, and encoders for digital setting circles. I received a timely response from Dave a few days later. He gave me a date on which the scope would be finished as well as contacts for shipping instructions.? During the next 3.5 months, I had a few email conversations with Dave about the scope. He added another mounting board on my upper cage assembly and we discussed potential balancing problems with heavy eyepieces. On the day that he said the scope would be completed, it was completed.


Obsession ships their products through a local Mailboxes Etc. I had anticipated shipping costs to be around $250. I was shocked when I discovered the cost was to exceed $450. I charged the shipping to plastic with Mailboxes Etc. and anxiously awaited delivery.

The shipment arrived 5 days later in several boxes. All equipment was professionally and securely packaged.? It was nice to know that the shipping moneies were well spent. All of the components were custom fit with "expandofoam" covered in plastic.? The shipment could have fallen off the truck and not be hurt.

The mirror had arrived two weeks earlier from QSP.? I had been very concerned about how I would mark the center of the mirror for collimation. But either Nova or QSP had etched a fine little cross right in the middle.

I was ready to rock and roll.

First light

Take a look at my first light observing report for my first night out with the scope.


One of the first things you do with a new telescope like this is set the primary and secondary mirrors and collimate them. I had never done this before. I followed the directions that came with the scope. They were simple and straight forward. I was happy however to get some help from more collimation savvy friends that I observe with. I set the primary in fairly well with only a thumb print on one edge.? The mirror sits on top of a floatation cell. Imagine supporting a mirror with your palms up and fingers extended. This is what the cell does with metal and rubber. The mirror is bound horizontally with a cloth web sling.? I admit that it took me a bit to figure out just how the adjustment bolts worked with this sling. But the concept is very simple and I finally got it.

On the first night, we had a devil of a time getting the secondary mirror just right. There was nothing wrong with the scope, we just couldn't get it set right. One of my companions managed to strip the phillips head screws on the secondary support.? I replaced them with hex head equivalents which are far superior.? Now they work fine.

During the same night, I had to borrow a 2" extension to use a 12mm Nagler eyepiece. I have since purchased one for myself. I couldn't get the scope to focus well without it.

If I lower the primary mirror somewhat, I insert the eyepiece not quite all the way and I can bring it to focus.

The scope is a joy to set up. For the most part, no tools are required. I always like to make a slight minor adjustment or two on the secondary to make sure that I have a perfect collimation. This does require an allen wrench (since I replaced the phillips screws with allen head screws). I carry a couple of 5/8" wrenches in case I need to make a fine adjustment of the primary sling.

Obsession18.gif (52562 bytes)
Mark Wagner's fingers turn up in many of our group's photos. Here they appear above my head and my new Obsession.

The design of mechanical components is very good. The scope glides effortlessly to any point in the sky. One night under ideal conditions, I bumped the power up to 1200x for some moon observation. I swear that we were in a space capsule

I use the wheels and handles to load the instrument into my minivan on ramps made from 2x8 lumber. I can easily move the scope in and out of the van. I can honestly say that the scope components are even easier to move around than my old C8 with its bulky hard case.

What I have seen

Over the course of its first year, the Obsession left home for remote observing for a total of 65 nights. Certainly, I have become a hard core observer!? The scope helps prompt me to get out.? It's images are a delight to my soul.? After receiving the scope I pulled out the list of objects I had prepared.? It contains some 4000 objects including all of the Herschel, Messier, and other objects I took note of during the months I waited for delivery.? I also purchased the Harald Boproff start atlas.

I have taken great delight in chasing down the faint fuzzies on my list. I must say that it is seldom that I can not find something... and when I get to a darker sky, even these are found without much trouble. What really astounds me is that I consistantly find objects not in my list or not in my atlases. The large galaxies and nebualae are breathtaking and always consume the first couple of hours of my viewing sessions.? Visitors always love looking at these, and I truly enjoy showing them off and discussing everything about astronomy.

I participate in many public events where we share astronomy and the science of the heavens. I remember last summer, at Yosemite's Glacier Point, I was showing the public Stephen's Quintet, clearly visible at the eyepiece.? Stephen's Quintet is typically a challenging object for novices and fairly dim. Yet this night the conditions were right and the scope was performing flawlessly. I told each observer to remember that they had seen this object. As the news got around, other scope owners expressed their surprise that these visitors had seen this wonderful galaxy cluster.

But, when I get serious, I love to work on finding new objects on my list.? I make it a point to find at least one per session.? This way, I will see something new each time I am out.


For observational astronomy, there is nothing like aperture. And the 18" comes in solidly. I have viewed through a 20" Obsession and though there are many variables to consider, I stand firmly in believing that the scopes are quite similar in what you "can" see.? Only the very very dim objects seen in the 20" will elude detection in the 18".? In terms of comfort there is a great difference. For the most part, I keep my feet on the ground.? Once in a while, I will use the first step on a small kitchen ladder to get to the eyepiece. This means a lot to me.? I don't like contortionism on ladders or on the ground... especially when I am out all night in the cold.

Epilogue (2 years after receiving the scope)

I have no regrets in purchasing this instrument (as I do with other equipment I have). I haven't really been able to get the encoder to work in the azimuth axis. The collar slips. It hasn't been a problem though... or I would have fixed it. I have found that locating objects is not difficult and in most cases, encoders and a DSC actually are a hindrance.? Other than that, the scope still performs flawlessly. With that and my enthusiasm for deep space observing, the lines at star parties have become a nuiscense for those attempting to observe near me.

July 4, 2004.? Since I wrote the review for the Obsession telescopes, I have ventured into the telescope business.? I still maintain that the Obsession telescopes are fine products and I have not changed the above review in any way.? Are mine better?? I'd like to think so.? I encourage anyone thinking about purchasing a telescope to examine the features and quality that you'll be buying with your hard earned dollars.? Spend your money wisely and you will be thrilled with the results.