You are currently viewing May 06, 2022 – Testing New Wide Field Setup

May 06, 2022 – Testing New Wide Field Setup

Objectives

  • Test if modified (i.e. shortened OTA) ED80T CF can reach focus with Sharpstar 2.5″ Field Flattener
  • If yes, capture images to measure FWHM, Eccentricity and imaging capability of this new wide field setup

Tasks

  • Mount Camera on field flattener + Moonlite focuser + ED80T CF and rotate accordingly
  • Mount ED80T Setup on CGEM
  • Connect cameras and focuser
  • Balance (might need counterweight)
  • Lock focuser clutch and set focuser to postion 0
  • Create new Sequence Generator Pro profile for Wide Field Setup
  • Reset focuser to 0 in Moonlite driver
  • Power on
  • Open roof
  • Remove caps & Install Dew Shield Extension on guide-scope
  • Launch Sky Planetarium +Open Location File + Connect to mount + Star tracking
  • Launch SGP and connect equipment
  • Move focuser to position 2000 (i.e. rough focus approximation)
  • Slew to bright star (Ed Asich)
  • Find focus using SGP from position 0 outward
  • Run autofocus
  • Plate Solve and adjust rotation angle in SGP
  • Calibrate auto-guider
  • Test autoguiding
  • Make test images
  • …

Results

Notes

Focuser position: 2000, 2500, 3000, 3500, 2900, 2800, 2750, 2200(slip), 2750

Test exposure at 1s, binning 1×1

Focuser lifting capacity was most likely too low. Focuser could not remain in position. I used the adjustment screw to increase tension on the drawtube (about 1/20th of a turn).

Autofocus exhibit weird behavior… still slipping… tightened a little more.

Autofocus success at 1.1 HFR with a quality of 99% Position: 2754

Platesolve & synch successful. Autoguiding also successful at 0.6″ RMS.

Image seems to suffer from some tilt.

Must try without field flattener!

Looking forward to use the TSKolli apparatus to test collimation
There is also seems to have some diffraction spikes on the stars (it’s a refractor). I am suspecting the screws holding the aluminum threaded rings.

Next steps:

  • Check and correct if screws inside tube are in the light path;
  • Test without field flattener;
  • Check if extension rings might have tilt;
  • Test with Compression ring instead of threaded extension tubes.
  • Possibly collimate the focuser (which method, TSKoli)?

Clearskypix

You can call me Frank. I've been an amateur astronomer since 1988. In 2004, I purchased my first astrophotography equipment. In 2008, I built my own observatory. I cannot count the number of hours I have spent building, learning and trying. It as been a humbling experience that I hope will continue for a lifetime.