telescope thread

Discussion in 'General' started by Matt Greenwolfe, Feb 1, 2019.

  1. Matt Greenwolfe

    Matt Greenwolfe Standard User

    Joined:
    Feb 1, 2019
    Messages:
    2
    Location:
    Cary, NC
    A few years ago, I bought an SBIG ST-7XME-D which I have used with limited success with my high school students and our 20 year old Celestron Ultima 2000. The Celestron is in need of refurbishing. I've never collimated it to my satisfaction, and the gearing no longer engages precisely or accurately.

    Alternatively, we could purchase a new telescope. My question is if you would have recommendations on a good purchase that would work well with the camera. Through fundraising from various sources, I'm guessing our budget would be about $10,000. We have an observation platform with mounting piers at the remote corner of our campus, but no observatory and not the greatest seeing or transparency. In other words, with limited budget and facilities, we are looking for something we could store, bring out, align and set up, observe and put away in one night, rather than something that would remain permanently mounted and aligned. It would be nice if it's portable enough to take to another location to observe as well.

    Last year, we measured the eccentricity, semi-major axis and period of the moon's orbit. This year, our project is to measure the astronomical unit as accurately as possible through our own measurements. We have also taken astronomical photographs of various solar system objects, but never been successful with deep space objects. I am a physics teacher, with an interest in astronomy but lack an extensive academic or amateur astronomy background. I'm basically learning along with my students. That hopefully gives some idea of our capabilities and the range of uses we are looking at.

    I would appreciate any advice on whether its worth refurbishing the Ultima 2000 vs. purchasing a new telescope, and what you might recommend for a new scope that would interface well with the camera.

    Thanks,

    Matt
     
  2. Colin Haig

    Colin Haig Staff Member

    Joined:
    Oct 27, 2014
    Messages:
    2,063
    Hi Matt,
    I'm sure other folks will chime in.
    There are quite a lot more options today than there were back in the mid-90's when the Celestron Ultima 2000 was new.

    Here's a few thoughts:
    1) The mount is really important. Consider getting a really good mount that can carry the weight of the optical tube, camera, and focuser.
    It should have a Losmandy style dovetail and/or Vixen style dovetail slot. That way you can insert any optical tube in the dovetail with appropriate brackets.
    The old Ultima fork arms, motors, electronics were never particularly good.

    The newer mounts range from inexpensive SkyWatcher german equatorial (GEM) to premium Astro-Physics Mach1 or bigger mounts.
    Software Bisque makes a great mount, but you have to have a laptop to control it.

    2) You could consider "de-forking" the Ultima.
    If the optics are decent, and the focuser works, you could junk the existing mount and buy a set of tube rings/brackets/dovetail hardware and put the existing tube on a new mounting bracket with a new mount.
    https://www.admaccessories.com/

    3) There are a lot of options out there for telescopes. The SCT/ACF/RC types are compact, better than refractors for what I think you are trying to do.

    When you narrow down your list, consider posting back here.
    Good luck and have fun!
     
  3. Matt Greenwolfe

    Matt Greenwolfe Standard User

    Joined:
    Feb 1, 2019
    Messages:
    2
    Location:
    Cary, NC
    Thanks for the advice. I am not sure about the optics of our current tube from the Ultima 2000. Its an SCT, and I have never been able to successfully collimate it. I can never get rid of all of the asymmetric flaring. Should I be able to perfectly collimate it, or are there some limits to what I can do? If so, are the limits to what I can do related to SCT's, or to the Ultima 2000 in particular? If it weren't for the collimation issues, the optics is otherwise still pretty good.

    If I did replace the tube, do you have recommendations to get me started looking?

    As far as mounts, what makes the Software Bisque mount superior to the similarly-sized SkyWatcher? I have no problem needing to control it with the laptop computer, and in fact prefer that.

    Matt
     
  4. Colin Haig

    Colin Haig Staff Member

    Joined:
    Oct 27, 2014
    Messages:
    2,063
    Hi Matt, it's a combination of budget and performance.
    Celestron Edge HD optical tube assemblies (OTAs) are quite good value for money as are the Meade ACF scopes; Planewave makes a superb product, but is a bigger investment.
    Software Bisque and Astro-Physics mounts are high-performance, with low periodic error (mechanical error from the worm/gears that introduces wobble that shows up in the stars). Pointing accuracy is superb with both.
    But they aren't cheap.
    I personally have a SkyWatcher EQ8, and am savig up to replace it. Some mechanical elements are quite poor, including simple things like fasteners that rust and places where moisture accumulates. The optical encoders don't actaully work right, and so have to be turned off to get accurate pointing.
    The Celestron and SkyWatcher mounts share some commonalities - manufacturing in China at some of the same factories; Synta owns both brands. Tolerances and consistency are getting better.
    For astrophotography or precision work, you want a really good mount.

    As far as collimation goes, you migh see if there is a local astronomy club near you - one of the members might be able to help you evaluate the Ultima 2000 OTA. The scopes have come a long way in the last 20 years.
     
  5. Mike Hambrick

    Mike Hambrick Cyanogen Customer

    Joined:
    Jul 13, 2016
    Messages:
    104
    If you are going to be doing most of your work using the camera rather than visually I would recommend something like a Tele-Vue NP101-is and an Astro-Physics Mach 1 GTO mount. You can capture a lot of really faint objects with relatively short exposure times and then display them on the computer screen for the whole class to see. Unless you get a really big scope, most deep sky objects look rather disappointing to students when they look at them through an eyepiece.
     

Share This Page