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Mike's New 25 Inch Obsession Telescope
Here are some photos I took on October 26, 2003 at my brother Lynn's house in Seaside, CA. Lynn and I have been working on adapting a Little Giant A-Frame ladder that I bought at Costco for use with my new 25" Obsession telescope. As you will see in the photos below, this scope really needs a ladder!
Pre Setup
Here you see most of the components of the scope. Of course, the main part is
the mirror box (which holds the 25 inch primary mirror), which rests on/in the
rocker box. The D-shaped thing you see is the bearing surface. This allows the
mirror box to pivot on the rocker box.
The bearing surface is formica and rests on teflon pads for smooth motion.
You can also (barely) see the truss tubes sitting on the rung of the ladder,
and the Upper Tube Assembly (UTA) which holds both the secondary mirror and
the focuser.
The removable wheelbarrow handles allow one to easily move the box, which is a
good thing because it weighs nearly 170 lbs. I have a pair of ramps that I use
to help roll the scope in and out of my van.
A Closer View
Here is a closer view of the box, showing the cover (which protects the very
expensive primary mirror from dust, falling objects, etc.), the truss pole block
clamps (whose function you will see below) and the guidance computer. The Obsession
telescope is designed to be used either with or without motorized guidance. The
motion when moving the scope manually is very smooth. It's a very well crafted
piece of equipment. But if you want, you can get a motorized tracking system
installed. It can be used both for "go to" astronomy (where you input the name
of the object you want to view, and the telescope points itself at that object)
and tracking (where the scope automatically adjusts position to compensate for
the rotation of the Earth... the object stays centered in the eyepiece field of
view).
Here's a shot of me with the box. I'm about 5'9", so you get an idea of the size
of this thing.
Attaching the Truss Poles
The UTA is attached to the telescope at the ends of the truss poles. The poles
are attached to the box via the block clamps. Here you see my brother Lynn putting
the poles into the clamps.
The block clamps are really ingenious little things. To keep the poles secure, but
not run the risk of squashing the ends (they're made of aluminum), a wood block is
fabricated with a large hole for the tube to fit into, and two cuts made in one
side running almost all the way to the other side. When the tube is fit into the
hole, and the knob is tightened, it puts just the right amount of pressure on the
tube to hold it in place, but not crush it.
The Upper Tube Assembly
Here I am on top of the ladder, seating the UTA. The tops of the truss poles fit
into special sockets on the UTA. Wedge-shaped blocks are placed between the tips
of the poles and tightened into place with a cam lever.
Here's Lynn tightening one of the cam levers.
And here's a closeup of the truss pole/wedge/cam lever assembly. When the cam
lever is tightened, the cam pushes the wedge up between the truss pole tips,
forcing them outwards. The socket that they're seated in prevents them from
moving outwards any further, so they're locked into place.
Finished!
Here's what the scope looks like when it's assembled. It can move from vertical
(as you saw in the previous pictures) to horizontal, and turn on its axis 360°.
When properly balanced with counterweights, it can be put into any position and
it will stay there. In this image, I'm holding it up since the primary mirror
isn't in place yet. The primary weighs around 90 lbs, so there's a lot of missing
weight at the lower end of the scope.
Ladder to Success
Unless the object I'm looking at is near the horizon, I'll have to use the ladder
to see through the eyepiece. When the scope is pointing straight up, the eyepiece
is 10 feet off of the ground! So I bought a ladder at Costco. It's a
Little Giant brand. As you can see
if you follow the link, it can be configured into many different sizes and shapes.
I use it in A-Frame mode, fully extended. However, it turns out that in order for
me to see into the eyepiece at 10 feet, I have to stand a little higher on the
ladder than I'm comfortable with. So my brother Lynn came up with a platform and
rails to make it easier to stand on the necessary rung. (Please excuse the poor
stitching of the panoramic photo, I really should have used a tripod for this
shot)
The shelf "keys" into the space between the ladders vertical rails, and rests on
the rung that is the highest recommended rung for standing when in A-frame
configuration (it's an OSHA rule).
The shelf is held in place with a couple of sliding blocks of wood that hook under
the opposite rung.
Six Months Later
Well, I'm still waiting for my mirror. Apparently Nova Optics (the guy
who was supposed to make the mirror) has gone out of business or something. Anyway,
he's not answering his messages. So Dave Kriege at Obsession Telescopes has put in
an order with Galaxy, a company with a much better reputation. I really should have
gone with Galaxy to begin with, but I went the cheap route. Now I'm paying for that
decision.
February 22, 2004
I just got word that the mirror from Galaxy is finished, and should ship on the
24th. So I should have it very soon!
February 28, 2004
IT'S HERE!!!!
Go to the mirror installation page!
Here's a picture of my scope in its new home, a shed by my house. I don't have a
garage to store it in, so this will have to do. Besides, it doesn't fit through
the doors of my house!
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