Hello all and welcome to part 1 of "Adventures of a dobsonian enthusiast who is a cheapo but still acquires equipment to use"
Chapter 1: The Obsession (the telescope brand that is)
I have been a fan of the dobsonian design for a very long time. My first exposure to this design of telescope was looking through the eyepiece of a 18 inch Obsession. I don't actually remember what I was looking at but the view was spectacular. Leagues better than the view through my own cheap chinese 6 inch newtonian with cheap chinese plossl eyepieces. This was when I learnt about the advantages of the dobsonian....the large aperture for the price stuff. I only realized much later that the telescope I was lucky enough to look through (the 18 inch Obsession) cost a tad bit more than my car......not counting the cost of the premium eyepieces to go with it.
Nevertheless, I started searching for a cheap second hand dobsonian, preferably one that I could actually carry to a star party single handedly.
Chapter 2: The facebook find and the 'perfect telescope'
As luck would have it I found an ad for a used 10 inch Bintel dobsonian on facebook. The telescope was listed as "In perfect working order" and the demand was a suspiciously low 250 Aussie dollars. This was in the beginning of December 2020. The only problem was that the location of the ad was somewhere near Newcastle, about 65Km from my home. Nevertheless I messaged the lady and set up a meeting. This was my first look at the telescope (well the first picture...but you get my point):
Upon closer inspection these were my impressions:
-The OTA looked fine, a few small dents here and there but very minor
-Secondary mirror looked ok, spider vanes are not bent
-Focuser was stuck, fiddled with the locking screw and managed to get it to work but it still gets stuck somewhere in the middle of its travel
-Mirror looked ok, a lot of dust and some marks on it but un-damaged
-The altitude bearing worked, this is good
-The azimuth did not work....at all. The base has water damage and probably cannot be fixed
All in all I thought it was a good find. I handed the nice lady the $$ and picked up the scope. The OTA fit snugly in the back seat of my car and the base fit nicely in the trunk.
I drove home a happy man. Driving back from Newcastle to Sydney all I could think of were the amazing views this scope was going to provide me. If I could fix the problems with the telescope that is.
The fix-up
Ok so first things first, lets get this thing to actually move around so we can look at stuff in space.
God bless Andrews communications!(
http://www.andrewscom.com.au/) This guy set me up with a brand new GSO 10 inch dobsonian base for 100 kangaroo dollars and a new GSO dual-speed focuser for 189 koala money. Laser collimator for 60 dollaroos. So I got home and fixed the telescope.....I got it actually working! I couldn't believe it, this was the first time I had a large aperture telescope that was actually working!! Yayy
Chapter 3: Washy wash wash
So of course the first thing I did was wash the mirror
I was really careful though, and it turned out to be an easy process. Just make a mark where the mirror assembly fits onto the tube (so you can fix it back perfectly in place without causing it to be rotated and out of alignment with the tube) then unscrew it and pop it out of the tube. The only thing you need to be careful of is to place the whole thing on a mattress or a soft place so when the mirror assembly pops out and if you don't grab it, it will not be damaged. Now just remove the mirror itself from the assembly and give it a wash in your kitchen sink, be careful not to rub the surface with your fingers or towel or any cloth....if you really need to rub some marks off then use high quality cotton balls. I just rinsed it with warm soapy water and the marks and dirt came right off. *Edit: I also used a bit of distilled water to rinse it as a final step, this will remove any water marks you might get from rinsing with tap water
The mirror 'before':
And now behold the 'after':
The secondary mirror and collimation screws:
Back of the OTA, mirror housing and collimation knobs:
New crayford focuser courtesy of Andrews communication:
And so with a happy heart I took a look out the window to see if weather permitted a bit of observation tonight.....
Dammit!!
And this went on and on and on and......I know *sigh*....new telescope weather.
