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Lawrence Parchman

Sculptor Galaxy (NGC 253)

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Posts Made By: Kevin Beebe

March 8, 2004 01:43 AM Forum: Telescope Making

Upper cage clamping problems

Posted By Kevin Beebe
I had some problems with the Astrosystems clamps on my 22" dob, just like you describe. The cause of the problem was the poles were slipping in the clamp blocks on the mirror box.

April 2, 2004 07:44 AM Forum: Telescope Making

Another ATM152

Posted By Kevin Beebe
Well, that settles it. I'm going to paint my telescope red!! Sure looks nice.

April 8, 2004 04:48 AM Forum: Telescope Making

center spot a diagonal

Posted By Kevin Beebe
I don't know about directions for center-spotting a diagonal. I've read a lot of people arguing against it, but some others recommending it.

There are excellent directions for how to square up your focuser on the Obsession Telescopes website.

Have fun,
Kevin

April 8, 2004 04:58 AM Forum: Telescope Making

Focuser mounting

Posted By Kevin Beebe
Getting your focuser as close as possible to the secondary has the benefits of making the fully illuminated field of view as large as possible and making the diagonal as small as possible.

And it causes the focuser tube to extend into the light path (unless you have a Clement focuser), makes using a filter slide problematic, and makes baffling more difficult.

Since diagonals come in discrete sizes, I love the convenience of a filter slide, and I notice a loss of contrast due to improper baffling more than a slight loss in field illumination, I chose to build my telescope with a slightly longer focuser-to-secondary distance.

It also lowers the EP height a couple inches.

Hope this helps a little,
Kevin

April 14, 2004 05:21 AM Forum: Telescope Making

Focuser placement - 90 or 45 deg

Posted By Kevin Beebe
Craig,
I agree with Michael (and the others). If you use a ladder at all 45 may be too much and 90 is uncomfortable at low altitude. I have set the focuser on both of my telescopes (16" and 22") to about the 60-70 degree position.
Kevin

April 26, 2004 09:27 PM Forum: Telescope Making

Where to find Carbon tubes?

Posted By Kevin Beebe
Hi,
I bought mine at Maclean.
http://www.macqc.com/tubing.php
At the time, they were about half price for 3/4" ID rolled tubing.


June 6, 2004 05:57 AM Forum: Equipment Talk

What is the Problem???

Posted By Kevin Beebe
To me, this looks like coma. What is the focal ratio of your scope? I would suggest reading Rick Shaffer's article "Wild Card 001.1

June 8, 2004 12:53 AM Forum: Telescope Making

Correct Image Newtonian

Posted By Kevin Beebe
Something like this might work. But it's only 1.25". sad

http://www.buytelescopes.com/product.asp?pid=1130

June 11, 2004 05:00 PM Forum: Equipment Talk

Binoscope VS Binoviewer

Posted By Kevin Beebe
Building a binoscope is much more difficult. You've got to have matched primaries. Then you have to collimate each side of the scope, and then be able to merge the two images.

Optically they are a little different also. If you keep the focal length the same the two telescopes (18" vs 12.5") the 12.5" might be an f/6 with a 75" FL. The 18" would need to be f/4.16, so much more coma and chance for other optical defects. If you keep the focal ratios the same, then you are going to have a smaller field of view, as well as a ladder to deal with.

August 5, 2004 04:37 AM Forum: Equipment Talk

Great scope deal at Anacortes

Posted By Kevin Beebe
It's an incredible deal. An OTA and mount for less than the OTA alone.

A friend just got the Advanced mount with an 8" OTA. I was impressed with the Goto and the stability of the mount. I wonder how well it would hold up under an 11" OTA...

I also saw sales for Televue eyepieces. Looked like they were cheaper than the traditional used prices. Are these permanent price reductions or just temporary???

Kevin

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