Just finished my latest project - a scope based on the Greg Babcock/Obsession UC et. al. design with a 22" diameter, 1.7" thick F3.6 mirror. The ultimate compromise between aperture and usability!
6 interlocking 1&1/4" poles bolt directly to steel brackets connected to the sides of the mirror cell at the bottom and steel brackets bolted to the steel secondary spider at the top for maximum strength and rigidity.
Oversize bearings allow scope to balance and foldover for transport and storage. Continual strips of teflon and rounding over the tips of the arc on the rocker mean that the join in the bearings is not felt as any "bump". The bearings are reinforced with steel to make them nice and strong.
Accessories include Moonlite focuser, Secondary Dewguard, Telrad, Argo Navis and Servocat Junior for GOTO
The Servocat Junior may seem a little undersize but they have been fitted to 17.5 Discovery scopes - this scope is the same weight with better leverage due to a greater diameter ground board and Altitude bearings.
Some more quick shots. Took it to Clayton Bay on Saturday for "first light'. I arrived at Clayton full of trepidation, as this was the first time I was going to give the new 22 inch compact scope a run. I had only finished it on Wednesday and had not even had time to do some quick viewing at home.
While the others were setting up their imaging gear, I put up the new scope to find that it did not quite have enough in-focus on the brighter stars shining through the twilight with the parracor in its correct setting. Luckily, I had plenty of travel in the collimation bolts so all I did was wind them up a bit and it was fixed. After dusk I collimated and initialised the Argo Navis/Servocat and begun observing!
Eyepieces used were the 28mm UWAN (80X), 13mm Nagler(180X) and 9mm Nagler (260X) all with a 82 degree apparent field of view. They all worked well at the fast 3.6 focal ratio with the parracor in place, showing some slight abberrations at the very edge of the field, but better than in my F5 scope without a parracor. Viewing conditions were quite good, with a little bit of misty cloud only occasionally interfering with the viewing and the smoke haze much less than it had been in the previous week. Seeing was typically excellent for this location.
I was curious to see if there was a noticeable difference on objects from the 16" so I spent the early part of the night viewing common favourites to find out. The 22 inch collects nearly double the light of a 16 inch and I was actually quite surprised at how this was immediately apparent at the eyepiece on all objects. M42 was very bright, with the centre glowing its pale green light, but the big difference was the slight pink tint to the nebula around this centre part. 47 Tuc showed red colour in its stars. The Ghost of Jupiter at 260X was an aqua green colour, and the double shells of the nebulosity were very bright. IC 418 was a subtle fuzzy star in the 16'' but in the 22" you could see the central star a bluish tint in the inner area around the star, and a rasberry tint to the outer ring. Galaxies were much brighter and the details within them was much more obvious. M83, M104, Centaurus A and NGC 1566 were especially spectacular!
Higher powered views were excellent as well with the Homunculus as well as Saturn appearing very sharp and bright with Titan appearing like a disk. Later on in the evening I did a tour of Galaxies in Leo, but the light pollution from Adelaide was a bit more in that direction, so I switched and toured around Centaurus instead. Also looked at many other objects besides and I've decided to let myself start to get very excited about the scope. Left about 4.30 am as the moon was rising.
what an awesome project -congratulations on completing your work - it looks fantastic.
is it a two person lift into the car?
Thanks,
Yes a two person lift or up two planks with wheelbarrow handles and trolley wheels. I can lift it myself - just- but wheeling it around is much easier and safer. The handles take less than a minute to bolt on and off.
Thanks for those extra base pics too..
I'm contemplating an 18 or 20" scope of a similar design or perhaps a slightly heavier build ala the SDM UC's - its always good to see some more examples.
With baffling a shroud is not really necessary at a dark site, where this telescope will be used. Besides, in a Newt. most stray light gets into the eye at the top end or from behind the primary and a shroud on this design just fills in the middle, so essentially does nothing to improve contrast.
Maybe I'll eventually make one so people at public nights don't drop their keys on the primary though.
Maybe I'll eventually make one so people at public nights don't drop their keys on the primary though.
Yes, that was my immediate thought. Keys, lollies, little fingers, coffee etc. I felt most uncomfortable with my 16" at public viewing nights until I had a shroud made up.
A plethora of congratulations Tim! What a beautiful looking piece of work - your tri dob 16" is a triumph, which you now seem to have surpassed. First light sounds fantastic - hope I get a chance one day to have a look through and at it.
Hi Tim, Glad to see your mirror has arrived and your scope is up and running OK. Hope it lives up to all your expectations. The 16 was a great bit of kit and I expect the 22 will again be something quite diferent and just as exciting to use.
Nice job
Congratulations.
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