Posts Made By: Thomas Dey

No great wisdom here but related anecdote: I used to observe with my wonderful old 12.5-in Cave Astrola in a dome at ambient temp...at times as cold as you mention. The only electronics were a Byers drive (120VAC synchronous), a freq controller to that, Edmunds +/-12VDC on the dec tangent arm, SBIG ST-4 CCD auto-guider system, FLI CCD camera and my laptop. The ONLY things I heated were the laptop (on a small heating pad set on LOW) and a blow-dryer shoved down my jacket. Everything worked fine cept skin flaked off my fingertips...and I set my jacket on fire once. Good luck! Tom Dey

Your paint spots on the deck are a good idea. If you get Polaris to correspond to the chart you should do nothing else. If a latitude scale doesn't correspond to yours...that would either be the scale is off or your mount is not quite level. Neither of those should matter---long as the whole thing doesn't tip over! PS there is an extremely accurate alignment that uses your main scope and looks for stars' drifts under high magnification. I used to do that once a year with a big observatory scope. With that you can nail the pole to within a few arc-sec if you're a fanatic like me. Totally unnecessary unless you are doing multi-hour exposures...which no one does anymore now that film is no longer used. Tom Dey

Sky & Tel Feb p50 has a good description and finder chart. 2004 BL86 will be scooting along at 2 deg/hour so you can easily see it moving just sitting (or standing) there. Peaks at mag 9.2. and scoots just W of Delta Cancer and just E of M44 (Beehive) between midnight and 2am (EST) on the wee morning hours of Tues the 27th. Traveling pretty much S to N. They are recommending a 3-4 inch scope or larger. I'll be using my 100mm binos sitting in a chair! (Here in Springwater, NY --- it will very likely be clouded out though...sigh). Tom Dey

Interesting! I of course viewed M42 lots but frankly never concentrated on color perception. Can never recall "seeing red" in diffuse objects, although stars can certainly appear so. I have that big (good!) "Dob in a Dome" with freshly coated enhanced mirrors, so would expect to see color if I'm physically able! I had cataract surgery and capsule perfed fore (of course) and aft. Colors in general look WONDERFUL now, so I'll give M42 a good long look. Thanks for the tip! Tom Dey

I added a BIG muffin fan to my 12.5 and would suck air down thru the tube for an hour before use (air filter over front end!). I experimented with a star image and even knife-edge during cool-down and the effects were very interesting to watch! The mirror had objectionable spherical aberration that would completely go away over about an hour. And sometimes fan on was better, sometimes fan off...depending on conditions. the fan (and scope and mount) were so good that fan on introduced NO vibration in the image! So I could toggle it on and off looking for effect. At (rare) times the scope would present little Airy Disc (= half arc-sec resolution!) if the atmosphere allowed. My best scope for CONTRAST was a 17.5" full tube I lined with sheet cork and then Black Velvet (measured BB diffuse R = 0.4%). Friends would actually comment on the great contrast without my asking. I think contrast is the most commonly unaddressed issue with most scopes...especially portable ones. Those ultralight minimalist Dobs are especially vulnerable. Tom Dey

Hi Charles, my two cents also. Certainly been there on my SCT and scared I would demolish it when I was replacing the existing back with the "Eye Opener" which has a bigger clear thru-hole. Catch-22 is some stuff we add onto the business end are SO heavy and cantilevered that if you don't go quite tight the whole thing can decide to spin when least expected. Like 2-inch diag with huge WF eyepiece, OAGs, cameras etc. I haven't ruined anything yet. At work, the techs would use "differential heat" in extreme cases. You heat the outer part FAST with a shop heat gun and twist off before the inner part gets as hot. Risk is of course ruining the thing with heat. At home I STARE at it a long time and then (if possible) take it out to the shop where I can brace everything in a controlled environment. Often anodized Al parts they fail to take into account the added thickness introduced by the surface hardening treatment. And if you break thru the surface the Al underneath is soft as butter and galls like glue so a bad situation gets far worse. In the most touchy situations I have added clocking constraints that don't rely on ultra-tight thread friction holding it. That's easy to do and fool proof, provided you don't mind customizing your stuff. I don't think I've helped...just venting same complaint as yours. Tom Dey

That's very nice! Some of the best planetary seeing I have experienced has been low haze.

My son got a nice plane transit of the moon with my hand-held snapshot cam at "10X." He's also a great shot with rifle, shotgun, machine gun. May take similar skills. I can't find that one but attached is a transit of the sun that I just stumbled across when I was imaging with a 4-inch scope. Tom Dey

Yeah - I followed that whole controversy and thought it was much to do about nothing. The professional astronomers were astoundingly at each other’s throats and it took YEARS to come to a formal agreement. The decision makes sense, technically...but it was far more about personalities and naming things than the orbiting bodies themselves. One of my FAVORITE imaging projects years ago was to image the star field (containing Pluto) with my wonderful 12.5-inch Cave Astrola and generate a (slide-show) sequence showing Pluto moving in its orbit. So I can truly say I have seen all 9 planets...or is it 8 + 1?! Anyway, I was able to see EARTH in broad daylight and highly-resolved with no optical aid whatsoever!

I've used the Q7 (borrowed from work) and most other types of scopes for everything from solar to moon and planet and deep sky. But by far my favorite all-purpose scope was a 17.5-inch Dobsonian in a nice 12-foot dome in the back yard. The trick was to use it full-aperture for Deep Sky (awesome!) and to pop a 6.5-inch off-axis stop over the front for high-res planetary. I would just rotate the stop with one hand to find the best wavefront and the planets were then every bit as good as the best apos. 6.5-in of fully apo unobstructed aperture. And then I could pop off the stop to see e.g. Saturn's moons pop into view because of the immense light grasp. The stop was made of black Styrofoam and weighed almost nothing. Best of all - the scope was inexpensive and user friendly. Setting circles allowed me to locate objects without even using the finder scope. I use a 29-inch now and intend to upgrade to a 36... but honestly, the 17.5 Dob was the most satisfying bang for the buck. Tom Dey