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Posts Made By: David Colton

July 27, 2002 04:50 AM Forum: Celestron

Collimation of Celestron SCT

Posted By David Colton

I plan on buying a new telescope and after comparing and contrasting the new GPS with a premium refractory, I had settled on a (Televue) 4" refractor. That was before I saw Celestron's recent rebate ($500) on their 8" GPS. However, I've read that to coax the best out of the optics, schmidt-cassegrain's need to be accurately and frequently collimated. Has that been the experience of most Celestron SCT users? Also, are their any tools/apparatus (such as laser collimators) that are recommended for SCT's. Thanks. Dave C

August 1, 2002 06:03 PM Forum: Meade

Meade 8" GPS

Posted By David Colton

Over the past several months I've posted a couple of questions about scopes, as I plan to buy a new one this fall. I was leaning toward a Televue 102, but with Celestron's $500 rebate, I'm now considering buying their 8" SCT. Along comes Meade with with their rebate offer (ain't competition wonderful). I checked this forum, but surprisingly, there really hasn't been much discussion about this particular model.

So my question is, how do users of the Meade 8" GPS SCT rate the scope? What are its strengths and what are its limitations? In particular, how would you rate contrast? (I'm thinking of buying a Televue everbright diagonal with whichever scope I purchase, as I understand it improves contrast.) Mechanical problems, etc.

Thanks. Dave C

P.S. I've really found the feedback of contributors to this forum very helpful.

August 22, 2002 04:33 PM Forum: TeleVue

TV 102

Posted By David Colton

I've been planning on purchasing a new telescope this fall and mulling over the various options. I had pretty much settled on buying a Televue 102 when along comes Celestron and Meade with their sales. Well, after considering a lot of factors, I've decided to go with the 102. (One of the key factors that influenced my decision was seeing lots of Meade and Celestron SCTs on sale here and other sites, but very, very rarely a Televue). I do have several questions though, which I hope some of you can answer.

First, is there any difference between the green and white TV 102 and the (newer) black and white model? I ask because I notice that one vendor charges somewhat less for the earlier green and white model.

Second, does the Gibraltor mount with Skytour have to be leveled?

Third, do the guide stars for the Skytour have to be 180 degrees apart? My yard slopes downward from the South and is heavily treed. As I'll be doing most of my viewing from this location, much of the Southern sky is obstructed and so I'll need to select guide stars primarily from the North and Northeast.

Thanks for your feedback.

August 27, 2002 04:18 PM Forum: Celestron

Portability of 8" GPS

Posted By David Colton

I have a Honda CRV and the height of the rear deck is 33 inches. Do the legs on the Celestron 8" GPS standard heavy duty tripod fold or retract so that I can load it into the car as one unit or would I have to take the telescope off of the tripod?

August 29, 2002 03:59 PM Forum: Equipment Talk

Who Made This Telescope

Posted By David Colton

I put this telescope up for sale earlier this month but didn't get too many inquiries. I think it may have been due to not knowing the manufacturer.

I purchased this scope in the early 1990's at a local camera store. It is a 4.5 inch mak-newt. It has a .935" focuser. It uses a unique flip mirror system to change from the focuser to a built-in 5x finder scope. The objective has the word "Soligar" printed on it, but I'm not sure if that refers to the manufacturer or model. It looks like the short newtonian konus Scope, but as I said this is a catadioptic telescope. It came with the equatorial mount you see in the picture.

I may have a rare gem or a entry level mass produced telescope (from somewhere in the world). Does anyone know the origin of this telescope?

August 30, 2002 04:18 PM Forum: Refractors

Orion 120mm Refractor

Posted By David Colton

Its my understanding that the longer the focal length of a refractor, the less chromatic aberration. Therefore, I'm wondering how Orion's 120mm / 1000mm fl performs. Their advertising literature says it is fully baffled, but what does that mean? I would think that the scope with a good diagonal (Lumicom or Televue Everbright) would have very good optical qualities. Any user comments? I'm especially interested in how it performs on planetary observation. Thanks.

September 6, 2002 04:13 PM Forum: Equipment Talk

Alt-Az Mount &DSC

Posted By David Colton

Does anyone know if digital setting circles can be installed on Vixen's Alt-azimuth mount? If so, what brand of DSC?
Thanks.

September 8, 2002 07:59 AM Forum: Equipment Talk

Vixen Alt-Az Mount and Digital Setting Circles

Posted By David Colton

I want to repost this question as I think it got lost in the discussion about AstroPhysics Refractors.

Does anyone know if digital setting circles can be installed on Vixen's Alt-azimuth mount? If so, what brand of DSC? I ask because Orion is discounting Vixen products and I'm thinking the Alt-Az with DSC would make a good grab and go platform for my small scopes.

Thanks.

September 15, 2002 08:02 AM Forum: Equipment Talk

Buying a Telescope - Part 1

Posted By David Colton

As I write this, I am enthusiastically awaiting delivery of a Meade LX90 from OptCorp in California. Next to a computer, this is one of the most expensive items I have ever purchased. I “discovered” the Astromart Forum about a year ago and like many contributors I used the forum to gather information about various configurations, brands, and models before making my selection. Therefore, I wanted to share my thoughts on the process and my observations about the telescope marketplace as well. Also, because messages on the forum are limited to 3000 characters, I’ll need to break this ‘article’ into chapters. So bear with me, as I’ll need to spread this out over several days and several messages.

I am in my mid-fifties and have been interested in astronomy since I was in elementary school. While in junior high I saved my lunch money up to buy my dream telescope, a 4” Criterion Dynascope. I remember that I had saved about $35 and asked my parents if they would contribute the additional $15 to make the purchase. They were of course incredulous that a “toy” could cost $50. After much pleading, they finally relented and I had my first telescope. I had that scope until my mid-twenties when I sold it. Quite honestly, I had difficulty learning my way around the night sky, so was never able to really appreciate the abilities of the instrument. (Which speaks to the need for experienced amateurs to help youngsters and newbies with the hobby.) My other optical purchase was a pair of 7x40 Tasco binoculars when I graduated from college. I still have it and it is still a credible instrument.

My interest in astronomy resurged in the early 1990’s. I bought a small (about 90mm) desktop mounted mak-newt for about $90. I think these were marketed by Tasco. A few attempts at finding things convinced me that I needed a bigger telescope and I was able to trade in the smaller scope for a 4 1/2 inch mak-newt on an equatorial mount for about $200 at a local camera store (see my question in the Astromart Forum “Who made this telescope” for a picture of that instrument). I thought I was set, after all this thing came with setting circles, those marvelous, but mystical apparatus that opens the wonders of the heavens to the uninitiated. What I didn’t count on was that use of the setting circles depends on accurate polar alignment and the directions for using setting circles often sound like they were written by astrophysicists.

September 15, 2002 08:03 AM Forum: Equipment Talk

Buying a Telescope - Part 2

Posted By David Colton

Part 2
As regards instructions for using setting circles, here are some directions for polar aligning from the celestron.com site: “First, choose your star near where the celestial equator (i.e. at or about 0o in declination) and the meridian meet. The star should be approximately ½ hour of right ascension from the meridian and within five degrees in declination of the celestial equator.” Hey, I didn’t know I needed to learn how to navigate a ship with an astrolabe in order to setup and use this thing. I think that Alan MacRobert got it right on the skypub.com site when he acknowledged: “In practice, experienced observers generally regard setting circles as decorations to help sell telescopes, as a source of false hope for beginners, and possibly useful as makeshift frisbees.” He goes on to add that, “Conventional setting circles are not a substitute for learning to find your way around the sky by looking with your eyes.” (Amen).

About three years ago I decided to take up that challenge. First, I started buying books about observing and about optical instruments, and read them cover-to-cover. I now had somewhat of a working command of the nomenclature of amateur astronomy. My library includes Turn Left at Orion, (which I believe is probably the best book ever written for newbies in the hobby), Star-Hopping, The Messier Marathon, Starware, and a number of the books in the Practical Astronomy series edited by Patrick Moore. I started subscribing to Sky and Telescope and have used the monthly pull out to find my way around the night sky.