Image of the day

Captured by
Yue Ma

HFG-1

About Astromart

My Account

New to Astromart?

Register an account...

Need Help?

Posts Made By: Craig Colvin

April 7, 2004 05:14 AM Forum: Telescope Making

New project - 18" truss conversion

Posted By Craig Colvin
I purchased this scope off eBay and am planning on converting it into a truss dob. I took delivery of the scope today and was surprised what a tank it is. It weighs 265 lbs!!! Definitely an opportunity for improvement there.

More pictures on my website.
http://www.craigcolvin.com/Astronomy/18in_truss.html

April 8, 2004 02:23 AM Forum: Telescope Making

Focuser mounting

Posted By Craig Colvin
I've seen a lot of discussions about people make truss dobs where they try to get the focuser as close to the inside diameter of their upper ring as possible. Some talk about using 1/4" plywood or 1/8" aluminum so the focuser can be right on the edge of the inside diameter.

Now I understand why you would want to do this from a vignetting perspective, but isn't it a problem that the focuser draw tube will extend into the light path when the focuser is racked in?

If you were going to add a filter slide wouldn't that also be a problem?

April 13, 2004 10:34 PM Forum: Telescope Making

Focuser placement - 90 or 45 deg

Posted By Craig Colvin
I am trying to decide where to place the focuser board on my 18" dob that I'm building.

I've noticed that a lot of big dobs have the focuser right above the truss poles on the side so that focuser is perpendicular to the altitude bearings (I'm calling this 90 deg).

Others have it more towards the back of the mirror box, 45 deg back from coming straight out the side.

The 90 deg would work great for viewing about 60 deg in altitude, but the 45 deg version would work best for low altitude viewing. Which is better? Does it matter?

June 8, 2004 08:11 PM Forum: Telescope Making

Finished my rocker box/laptop stand today

Posted By Craig Colvin
I have one week left before the Shingletown Star Party. Been working like crazy trying to get my 18" dob finished. Here was this morning's project.




more pictures on my web site http://www.craigcolvin.com/Astronomy/18in_truss.html

June 15, 2004 02:56 PM Forum: Telescope Making

First (second) Light?

Posted By Craig Colvin
I had first light for the new converted 18" scope last night. Here are the before and after pics.



It's second light for the optics but first for the new truss design so is that first or second light?

Still have a few minor things to fix, but it will be usable for the Shingletown Star Party tomorrow. Assuming of course that a conversion project doesn't affect the weather gods and there are clear skies.

Went from 265 pounds down to 119 pounds and made it so it now fits in my vehicle. smile

June 23, 2004 05:58 AM Forum: Deep Sky Observing

Seyfert's Sextet

Posted By Craig Colvin
I looked at Seyfert's Sextet, NGC6027, Monday morning in my new 18" scope. I could make out 3 galaxies 220x and thought I could see a 4th with averted vision. I pushed the mag up to 413x and could then definitely see the 4th. I couldn't even get a hint of the other 2 galaxies.

Is it possible to see all six galaxies with an 18" or do I need more aperature?

February 7, 2005 04:06 AM Forum: Telescope Making

Binocular Mirror Mount

Posted By Craig Colvin
I had never seen one of these before but heard about a commercial version last week. Next thing I know I've bought a front surface mirror and put this together yesterday. I think it's going to work out nice.



More details and images are available on my web site www.craigcolvin.com/Astronomy

It was too cloudy to try last night but there appear to be a few holes in the clouds tonight so I'm hoping to give it a try.

February 7, 2005 06:12 AM Forum: Astro Binoculars

Binocular Mirror Mount

Posted By Craig Colvin
I just posted this in the telescope making forum not realizing there was a astro binocular forum.
http://www.astromart.com/forums/viewpost.asp?forum_post_id=299276&poll_id=&news_id=&page=

I just finished building the mirror mount below. Only had a few minutes with it before the clouds rolled in but I think I'm going to like it.


April 1, 2003 07:30 AM Forum: Deep Sky Observing

Would you believe This Really Works...

Posted By Craig Colvin
You are 1 hour and 10 minutes early for April Fools day.

November 26, 2003 03:55 PM Forum: Equipment Talk

What type of finish?

Posted By Craig Colvin
I had been thinking of a hand-rubbed finish because that's what Michelle Stone decribes for here scopes (http://plettstone.com) and I've always liked the look. But perhaps they don't hold up well in the moisture.

I've only used Polyurethane once before on a dob mount and it doesn't look all that great. It also still feels tacky likes it's not fully hardened (and this is after 5 months).

I know I need to do something but I'm afraid to ruin my beautiful scope with a bad finish job.

Thanks for all the suggestions.

-- Craig

Funding Member

Sponsors


View all sponsors

Search