Image of the day

Captured by
Adam Livingston

Bubble Nebula

My Account

New to Astromart?

Register an account...

Need Help?

Pearls for using a big refractor

Started by RobertHowe, 05/02/2004 09:19AM
Posted 05/02/2004 09:19AM Opening Post
Hi Guys and Gals,

I am fairly new to refractors, having seen my first world-class one last August; having got the bug, I bought a very nice 130 mm f/6 in September and a 155mm f/7 last month. I intend the smaller one for routine viewing (at which it excells) and the larger one to replace an 11 inch Dobsonian for deep sky use.

I have been doing comparisons for the last few nights and find that, even more so than the fabulous optics and views, my overiding impression of the 155 is of...difficulty of use. On a Losmandy G11, the big refractor's EP is commonly near the ground. No problem, I'll just set the legs longer. Now, with the legs extended, the mount is so high that placing the OTA into the tube rings becomes a bit hazardous, as taking that weight up to my nose level is a bit of a challenge. It worries me that I will drop the OTA someday and be left with a multi K$ pile of glass dust and dented aluminum.

I'm pleased with the performance of the 155 on such deep space objects as I have viewed (the moon being fairly bright of late) and have worked out a routine for setting up in minimal time and effort (see below*), but I wonder if the aim of having a "killer optics" scope for DS use might be more safely met with a Mak-Next or Mak-Cass of similar aperture.

Any suggestions to make the 155 easier to use? The previous owner suggested measuring the positions of the OTA in the rings and of the counterweight on its shaft, which has removed the need for balancing the telescope on the mount at each use. Other pearls, anyone?



*Here's my routine.
Dinnertime, place telescope and EP cases on back porch to cool. Place mount on back walk, with legs on marked locations for rough polar alignment, and level it. Place counterwieght on shaft at pre-measured height for specific telescope.

Dusk, before Polaris visible, open up tube rings with hinges down, place OTA to predetermined location, add diagonal, finder, EP, tighten everything down, fire up Gemini and use to view evening planets or moon.

Evening, after Polaris visible, place polar alignment scope, align carefully, cold-start Gemini and view night sky objects.

1 am, tear down.

Robert Howe
Wilbraham MA

TeleVue 85 f/7 // Astro-Physics Traveler 105 f/6 // Astro-Physics 130 f/8.35 // Tak Mewlon 210 //
Coronado 60 DS
"Scopes, Brains and Wisdom--but no Beauty"