Posts Made By: Ron Harper

Ed,
What on earth was Dave thinking? I tried it. The initial stick is quite strong, followed by the most surprising, slickest, quickest scoot imaginable. Just horrible for fine tracking motion. Stiction in principle is a necessity, else the smallest force would move the telescope slowly. But when things are right, stiction isn't noticeable, and takeoff seems gradual.

If you ever get in a bind and have to have easier motion in a quick and dirty way, I recommend a bit of bar soap. It doesn't last well, soon gets gummy, but will get you through a night. It is the only lubricant I have tried that doesn't stick.
Ron

I have a 2-inch format 52mm focal length Antares Erfle, now out of production. It goes very well with my f/12 refractor.
Ron

Paul,
I'm getting in on this late, sorry. I don't own an off-axis scope like yours, but have read and though a lot about how to collimate regular Newtonians, of which I own three. They take some occasional tinkering to get right, as the refractor buffs love to remind us!

After some consideration, I am convinced that the the designer and manufacturer of the telescope knows how to collimate it. Follow his instuctions.

The secondary, as others have noted, is not a likely culprit, but is hard to test. To test your eye, rotate your head about the eyepiece and see if the effect stays put or follows your eye.

The burning question is, is the primary mirror astigmatic? First, as somebody already suggested, make sure the primary is not in a death grip. If it seems unstressed, of if loosening it a tad doesn't help, proceed as follows. Record the orientation of the elongations of a star imaged inside and outside of focus. Then, rotate the primary rougly 90 degrees. Do whatever you must to get some rotation. If the mirror mount can't accomodate a rotated mirror because of the difference in thickness from one side to the other, try to rotate the entire mirror cell in the tube. It doen't have to be 90 degrees, just some significant amount. Recollimate, and star test again. The scope should and must work exactly as well as before the rotation. If the in and out of focus elongations are rotated from their original orientations by the same amount that you rotated the primary, the astigmatism is in the primary.
Good luck, Ron

Thanks again guys. All your responses are inspiring. If I can ever get that house built out in darkest New Mexico, and just keep getting smarter and sharper-eyed as I get older(!), I may have a chance.

But Bill, you've got to lighten up. I feel sure even Messier let it go when he was watching a ball game.
Ron

Apperture rules. The "upgrade" will not be worth the trouble, especially if your observing is 80% deep sky, of the type that hardly requires Dawes' limit from a 16-inch scope. As for resolution, some of the best planetary images taken from earth are through scopes just like yours. Check the ALPO sites. Hooray for wanting better views, who doesn't, and for having money, but another 16" some-kind-of-Cassegrain is not likely to get you there.
Ron

Inge,
I agree pretty much with all the other responses, but would like to raise the issue of observing not mererly the annularity but the helicity, or the wrap-around appearance where the two ends don't quite meet. I have never been able to see this, even in some very dark sites and in scopes as large as 20". I have read only one report of a visual sighting of this feature, with an 8" SCT, from a site I know as the best I have ever visited. That site is jet black on the light pollution map. I never tried the Helix from there. So, there's the real challenge, in my opinion.

You'll probably see the central star too, if you look. You WILL look, won't you?
Ron

Buck,
You need full illumination over the field stop of a high-powered eyepiece, say 5mm, so you'll get full resolution where it counts. It sound like you're on top of that. But another concern is that at your lowest power, where the field stop may be 46mm in diameter, you need to have at least 70% illumination at the edge, or the image will appear dim near the edge of the field of view. Most people say 70% is a good minimum, and I agree, having tried less.
Ron

Robert,
Over on the Cloudy Nights Binoculars Forum (compared to which this place is a graveyard for uncoated binoculars at midnight) it is praised for its optical quality, but sometimes dissed for its narrow apparent field of view. Sort of a poor man's Takahashi Astronomer. Not having had the pleasure, I can't comment, but am envious.
Ron

Dmitri,
A 10x50 is really a lot of fun. This time of year, I guess any night sky observing at all is a treat for you Nordics. How can you possibly work in a place like Curacao?

My first view of Omega Centauri, barely, was through the thick, moist air on the beach in Florida. I remember thinking if it was visible at all through that murk, it must really be something.
Ron

Robert,
Nope. With my larger reflectors, my EP kit is one pure 2", three 2"/1.25" that get the 2" treatment, and a 7mm Nagler, which gets the adapter all to itself, so it becomes like a 2" eyepiece too. Just seems like less fooling around that way.
Ron