Charleston Observatory

Equipment

The use of Astronomical equipment combines multiple technologies: Optical systems, Mechanical systems, Electronic systems, and software, all working together in harmony.

The quality of the equipment employed during imaging is a big contributor to the final result. Note, while it is natural to equate spend with quality, there is a balance in this mix. Some not-so high-end equipment can actually be very good quality. And likewise, some more expensive equipment is sometimes junk, especially the mass produced equipment.

For any long exposure CCD imaging the most important equipment factor is a stable error-free mount that can accurately track the sky and can support the weight of the telescope and associated equipment.


Telescopes

A Celestron 8" Schmidt Cassegrain Telescope is used as the primary instrument.  The 8" OTA is FASTAR capable, originally an Ultima2000. The Ultima2000 was a nice GOTO scope but the mount had excessive periodic and other tracking errors. These tracking errors were very much limiting my imaging exposure time.

After fighting the tracking errors of the Ultima 2000 for some time, eventually it was realized that without better gearing and correction, the limitation would remain. I sold the U2K mount and switched this OTA over to an older Ultima 8 PEC mount for long exposure imaging.

The Celestron OTA on an Ultima PEC mount
The Ultima PEC mount is robust, and carries the 8" OTA and ED80 Piggyback with ease

The Ultima mount employs a precision Byers gearset, resulting in periodic error in the order of <5 arc-sec. The Tangent electronics include Periodic Error Correction.

Click on the links below for further details of the Ultima 8 PEC mount and circuitry


Tracking Platform on Ultima PEC mount
Other telescopes include an Orion ED-80 for widefield imaging and observing, a Meade 2045 SCT for guiding.

The ED80 and 2045 and DSLR with lens were used initially piggyback on the Ultima 8 PEC OTA.

Since then, I aquired another Ultima PEC mount, built a cradle for the forks, turning the mount into a tracking platform, on which various combinations  of gear can be mounted.

It was a successful project and the mount tracks as good as my other Ultima PEC mount, employing the same gearset and electronics.



During the use of any optical equipment in the night air, dew and frost on the lenses must be mitigated. The easiest way to deal with both is to apply heat to the sky facing lens.
Build a DIY Dew Heater Controller >  

CCD Cameras

CCD cameras employed over the past have been:

  • LX Modified Philips Vesta
  • LX Modified Philips Toucam Pro
From there, moved to dedicated CCD cameras... The MX716 was upgraded from the MX7C, exchanged the original colour filtered CCD chip for an ICX429ALL monochrome chip. Then upgraded to an SXV-H9 camera, then to an SBIG ST8300M camera
  • Starlight Xpress MX7C
  • Starlight Xpress MX716
  • Starlight Xpress SXV-H9
  • SBIG ST8300M
Astroimaging has been on a back burner for a while, due to some other priorities in my life. But occasionally I still make time to get out and take a few images.


DSLR Cameras

I use the dedicated CCD camera for deep sky imaging... and Canon DSLR cameras for widefield imaging, and webcams for planetary imaging, on a somewhat intermittent basis. I am more apt to do some quick grab-n-go visual observing of a comet passing through.



DSLR Astro Images
DSLR DeepSky ImagesDSLR Widefield Images

    For lunar and planetary imaging I still use a Philips Toucam Pro PCVC740K webcam with an eyepiece adapter threaded in place of the original lens. For Win7 I have switched to a Philips SPC900 webcam which also works on my old Win 98 PC

    Modified LX Toucam with Cooling

    Prior to the MX716, I modified first a Philips Vesta and then a Toucam Pro PCVC740K webcam for long exposure imaging. That was my first foray into long exposure CCD imaging

    Details on the SC1 mods... >
    Over a period of 5 years, I modified multiple Philips webcams for long exposure imaging, using the SC mod from Steve Chambers.

    Several have been for my own use, and others have been modified for friends. While I no longer use these cameras, the reward was significant - seeing deep sky objects appear on the screen after relatively short integrations (even 15 seconds)

    Below are some nostalgic pics of the a cooled CCD camera I built... using a Vesta SC inside.
    The Peltier cooler radiates heat through a heatsink.


    Filter Wheel

    A motorized filter wheel is used to index one of 6 filters into the optical path between the telescope and the CCD camera. With the earlier MX7C an external filter wheel was not required to attain colour images, but the sacrifice was reduced sensitivity and the inability to shoot narrowband and pure luminance frames.

    I started with a Homeyer MFW6 wheel, which I have since upgraded from, and am now using a Finger Lakes Instruments filter wheel. The thinner profile is preferred for focal distances.
         

    Filters

    The filter wheel contains True-Technology LRGB dichroic filters, as well as an Optometrics Ha 10nm filter. I occasinally use a Hutech IDAS NBN-PV filter.

    For IR blocking I use a Sirius Optics NIR-1 filter external to the filter wheel.

    Filter Wheel Electronics
    I am in the process of adding microprocessor control to the FLI filter wheel, controlling a stepper motor for indexing, and an LCD display. The end intent is to allow remote control and automated filter indexing, the control will be ASCOM compliant.

     
    Machining
    With the use of a small metal lathe, the fabrication of various accessories is achievable.
    The image below is the start of a focuser assembly.
    A lathe is a fantastic tool for making am-Astro DIY accessories.

    HomeImage IndexEquipmentSoftwareLinksContact
    2003-2020 CL Astronomical