Telescope Reviews: 8" f/5 Newtonian Astrograph

Yesterday I had one of those experiences where you knew it was a good story in the making. My goal was to test focus using the newly assembled sonotube OTA. I call this…

A PRACTICAL GUIDE: How NOT to test focus with a newly assembled astrograph OTA.

Step 1. Start with a pile of equipment that requires electrical power to get anything done.

Step 2. Drive to a location with no electrical power.

Step 3. Spend a solid hour fumbling around in the dark.

Step 4. Go home, get 4 hours of sleep, and go to work the next morning.

Last night I had a window of opportunity to get this done. After much consternation and deliberation I decided to strap the sonotube to my dovetail bar and test focus on Sirius. Other options were considered, but ultimately I wanted the ability to aim and track during this process. Going into this fiasco I had four devices requiring power:
- Atlas EQ-G
- QHY8 & power supply
- Laptop
- Motorized moonlight focuser

Kevin and I have access to a semi-dark site on a friend’s farm property. There’s always been electrical power inside a nearby shed. For the past two years we’ve been going there and plugging in with no issues. Last night I slapped everything into the sonotube and drove out to meet Kevin around 10:30pm. Skies looked beautiful. I setup and plugged in.

No power.

Flipped breaker. Still no power.

ARGGHHH!!!!!!!!!

I acknowledge that driving to the dark site was totally unnecessary. We were just trying to make an event of it, that’s all. We kept trying to think of ways to power stuff off our car batteries. Every idea came up short by one little missing part or adapter. The bottom line is that I came prepared to plug in and fate had other plans.

However, we succeeded in getting a fairly collimated visual image using various EP/Barlow combinations. I defocused on Sirius through a 26mm super plossl and 2x Barlow. Diffraction rings looked ‘good’ but not perfect. We also looked at Saturn with a UO 7mm ortho. Using some a make-shift project screen we basically measured where the image plane was relative to the top of the fully racked-in drawtube. Camera or not, it’s looking very good!

Lastly we took some photos of the most retarded-looking telescope in the world. How do ya’ll like these ratchet straps?

Everyone should be jealous of my voice-command GOTO system....

"Ok....Kevin, engage the clutchezzzz......NOW"

Hopefully I can test properly in my backyard very soon. Next step is to start popping holes in the hastings tube…..

Also, more to come on that issue with the secondary holder sticking. I talked to Bryan at Protostar and he recommended I ream out the hub gradually until it turns more freely. I did so using a sharp ½” bit in a corded drill. After four or five iterations I’m getting less sticking, but it’s still nowhere near the point of fine adjustability. I’ll work on it again for the final product, but for the sonotube testing I didn’t fuss over it any further.

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Curt
www.opticalsupports.com

Edited by imhotep (03/25/09 03:45 PM)