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Posts Made By: David Colton

February 20, 2003 12:33 AM Forum: Equipment Talk

Cool down time for a SCT

Posted By David Colton

I've read that it can take up to an hour for a SCT to obtain equalibrium with the surrounding air temperature and until then images may not be that good. Does anyone know where this assumption comes from? Why should a SCT take any longer than a refractor, for example, to cool down, as both have enclosed optics?

March 16, 2003 07:43 PM Forum: Equipment Talk

Eyepiece Case

Posted By David Colton

My son was showing me a "toolkit" he recently bought to hold audio equipment. It is a 18" x 12.5" x 6" (460x325x150mm) aluminum case with foam padding, plastic inserts to create dividers, and elastic straps on the inside, with a lockable latch and shoulder strap. It is of course the same type of case that is sold for eyepieces, which sell for $80 - $125. He paid $20 at Lowes. Check them out.

Dave Colton

March 16, 2003 07:56 PM Forum: Telescope Making

Replacing focuser on a schmidt newtonian

Posted By David Colton

I have a short tube Schmidt-Newtonian (see picture below) that I am trying to sell through the Astromart classifieds. In writing up the ad, I noted that it would might a good scope for a tinkerer as it could be improved by replacing the .965" focuser for one that accepts 1.25" eyepieces. I'm going to continue to advertise this scope, but if there are no takers I might become the tinkerer. As someone with no experience in telescope construction I'd like to pose the following questions:

In addition to being able to use my 1.25" eyepieces, I'm assuming that using a larger focuser will increase the amount of light reaching the eyepiece and therefore will improve brightness and contrast. Is this an accurate assumption?

Due to its folded optics design, the OTA is only 15" yet it has a 1000mm focal length. In order to bring images to focus there is a 4" extender that attaches to the focuser. Obviously the FL will not change, but will changing the size of the focuser and using larger diameter eyepieces have any affect on where the images come to focus?

I haven't removed the focuser yet to see how large the opening in the tube is where the focuser is mounted. To take advantage of a larger focuser will I have to enlarge the opening?

Light from the primary mirror is reflected off of the secondary mounted on the correcting plate at the front of the tube to a mirror that is attached by an arm to the focuser assembly. When I change the focuser will I need to
change the mirror as well? Also, are there any issues related to collimating this third mirror; for example would I need special equipment to collimate it?

Finally, are there any manufacturers of simple rack and pinion focusers that you'd recommend? Obviously, this would be an experimental process for me and I don't want to invest a lot of money, especially if I can't get it to work properly.

Perhaps the biggest question is if fiddling with a compound telescope is something a novice should do.

Thanks for your feedback.

Dave Colton

April 2, 2003 12:55 AM Forum: TeleVue

Sky Tour DSC

Posted By David Colton

I'm piecing together a Televue setup. I've purchased a Gibraltor mount and I'm now saving toward a TV102. I'm also thinking about buying the Sky Tour DSC, however I'd like to read the instructions for using them before making the purchase. In particular, I'd like to know what it uses for alignment stars, as my site is partially obscured by trees. Televue's marketing literature doesn't provide that much information about this product. Does anyone know of any web sites that would make this information available?

April 14, 2003 11:33 PM Forum: Equipment Talk

Scope Review Site

Posted By David Colton

Here's a (new?) astronomy site with scope reviews that I bumped into while surfing the net.

Astroscopic Lab:

May 18, 2003 11:19 PM Forum: TeleVue

Televue Users Group on Yahoo

Posted By David Colton

How do I go about finding and logging onto the Televue users group on Thanks.

May 27, 2003 11:27 PM Forum: Equipment Talk

Barlow Lens

Posted By David Colton

I'd like to purchase a 2x Barlow lens to use with my Meade 4000 series Plossl eyepieces. I see where Orion has their "Shorty Plus" 3 element 2x Barlow on sale and would like some feedback about this accessory. Are there any Barlows other than this model from Orion, under $100, that are recommended? Thanks.

May 28, 2003 11:56 PM Forum: Equipment Talk

Digital Camera for Astrophotography

Posted By David Colton

I just came across a review of Nikon's new Coolpix 5400, which will begin shipping this summer. Its a 5 megapixel camera that will retail for around $800. I was taken by its many features, which should make it very adaptable for astrophotography. In addition to being a high resolution digital camera, it has a shutter speed of 1/4000 to up to ten minutes making it suitable for longer exposures. for more information check out Steve's Digicam site:

June 17, 2003 10:56 PM Forum: CCD Imaging and Processing/Solar System

Digital Camera Coupling

Posted By David Colton

I'd like to try taking some pictures with my digital camera, a Casio QV 3000EX, which does NOT have a threaded lens. Is there a way to couple the camera to an eyepiece without having to use a camera adapter like that sold by ScopeTronix? Thanks.

June 24, 2003 11:18 PM Forum: TeleVue

New TV102

Posted By David Colton

I was finally able to work out the financing, so it was time to take the plunge and order my dream machine, a Televue 102. Better yet, I had just received a sale notice from a dealer and was able to work out a bit of a discount. When I came home from work yesterday, the boxes had arrived, but I decided to savor the moment and waited until after dinner to unpack the scope.

Well, I felt like the comedian Tim Allen doing one of his "Tool Time" routines. Buttery smooth focuser, yeah it is - arhhh. Black polished dew shield, arhhh. Look at the size of that 2" everbright, ARHHHH! And hey, this is one hefty mother. No light cup here, definitely a light MUG or even a bowl. Get this baby mounted on the Gibraltor, balance her out, and best of all, clear skies on the east coast for the first time in two months. Time to put the pedal to the metal and street test this beast.

Let's see, where's the 1.25" to 2" eyepiece adapter. Not in the box with the diagonal. Not in the box with tube ring. Not in the carrying case. Check the wrapping; check the boxes; check under the sofa in case it rolled onto the floor. AAAAAAAAH.

A quick call to the dealer and yes, a check of the inventory indicates that the adapter was not shipped; we'll put it in the mail right away. I'm looking forward to using my dream machine as soon as the adapter arrives. Of course, the weather forecast for this weekend calls for rain.