Posts Made By: Doug Culbertson

Here is a review of the PT3. Expensive, but looks nice!
http://www.cloudynights.com/mounts/Pier-Tech.htm

Doug
Midway, Fl

I check collimation every time I take either of my newts (dobs) out. If you opt for a truss tube dob, you will have to collimate every single time you set up. It is the nature of the beast, since you are disassmbling the entire scope, i.e. taking off the upper cage which contains the secondary, possibly removing the primary for transport, etc. I have managed to set my truss dob up to find that it was pretty well collimated without doing anything to it maybe twice out of hundreds of times that I have set up.

With a solid tube dob, it really depends on the scope. I have owned solid tube dobs that maintained collimation for what seemed like forever, though I still checked it every time I set up, as it is always possible for the secondary to turn, the primary to shift, etc. The 8" tube dob that I have now seems to need collimation a bit more often, probably 3 out of 4 times that I have set it up, but I have only owned it for about a month.

As to how long it takes, if you have never collimated a newtonian before, it may take you a few times until you get it down, but once you do it becomes second nature. I can collimate my truss dob in less than two minutes now, including a final autocollimation check. I use a combination of sight tube, Cheshire and autocollimator, but I also use a laser on many occasions as I tend to set up after dark a lot. Always testing with a star test at the end of collimation. It is not nearly as hard as some make it out to be though.

While searching for you Newt, check out these collimation sites:
http://zebu.uoregon.edu/~mbartels/kolli/kolli.html
http://www.efn.org/~mbartels/tm/collimat.html
http://www.efn.org/~mbartels/tm/collimat.html
http://w1.411.telia.com/~u41105032/myths/myths.htm

Just to keep you busy!

Doug
Midway, FL

The point? Well, I suppose it is to raise public awareness of the wonders of the heavens, as limited as that may be under mag 3 skies, and to point out what light pollution does to hide those wonders. Since the "big event" isn't 20 minutes away at the darker site, you go to where the crowds are.

The astro club I belong to sets up once a month in a downtown park, a la John Dobson, and the skies there are maybe mag 3 on a good night. Doesn't stop us from showing the planets that are visible, the Moon, and some of the brighter deep sky objects. The purpose is public outreach, not serious observing...we have our own dark site for that.

As to commercial gain, is your friend charging anyone? The crowds are going to be at the bookstore for the Harry Potter release whether your friend is there or not.

Just my .02,
Doug
Midway, FL

I have found the same thing. I am 47 and have minimal floaters, but found that they are eliminated when I use the binoviewer. I have heard from other people that noticed the same phenomenon when they binoview as well. I think that Russell is right in that the merged images mask the imperfections...

Doug
Midway, FL

Looks like a wolf spider...we get them around our house too. They are pretty docile, and much scarier looking than they really are. They capture food by hunting, rather than by using a web to trap prey. More information than you wanted?

Doug
Midway, FL

Heh! No kidding. I posted the link to that ad on my club's website. I figured that if someone in my club buys it, then I get all the benefits of getting to look through it, but without the problems of storing, hauling it out, etc. Win-win the way I see it!

The thing does look cool though, doesn't it?

Doug
Midway, FL

Paul,

Do you happen to live in North Florida? Actually, that has been the way it has gone around here since May . The "sea breeze front" coming off of the Gulf brings daily thunderstorms in the late afternoon and evenings, clouds linger until well after midnight, and when I walk the dog at 6:00 am it is usually clear to partly cloudy...and then it starts anew. We had 14"+ of rain in June, and it has rained all but two days in July so far. Ack!

Doug, slowly going crazy in
Midway, FL

Well, if it counts, I have a 8" Guan Sheng dob from Taiwan, the Hardin DSH8. I consider it a *very* good scope, and I say that as the owner of a Starmaster/Zambuto.

Crisp images, holds collimation well, easy to haul out and use, and it passed the "Jupiter test" which I consider to be better than a star test. I bought this as an occasional use scope at Hardin's ridiculously low price, but I think that it is going to get a lot more use than I thought it would...if it ever clears up here that is.

I don't think either of us just got lucky, I think that this is the norm for these scopes.

Doug
Midway, FL

Not to be a wise a**, but did you have it switched to N for northern hemisphere tracking? I have switched the controller on a GEM to S on more than one occasion myself and believe me, it won't track the northern sky worth a darn!

Doug
Midway, FL

Spectrum coatings, used by Steve Swayze and Carl Zambuto. Spectrum coatings uses Ion Assisted Deposition so the mirror substrate is not heated. I am about to receive my fourth mirror coated at Spectrum. It will cost you about $10 per inch for standard coatings.
http://www.spectrum-coatings.com/

Doug
Midway, FL