Imaging Performance Results

 

My relatively modest equipment consists of a 20cm F10 SCT equipped with a monochrome CMOS camera having a peak quantum efficiency of  81%.  My sky's limited magnitude is only 3.5.

 

I typically run the camera at the following settings...

 

Deep Sky

• Typical Exposure – 1 to 10 seconds.

• Number of Exposures – 100 to 200.

• Typical Total Intergration Time – 5 to 10 minutes.

• Moderately high camera gain.

 

Sun/Moon/Planets

• Typical Exposure – 10 to 100 frames a second.

• Number of Exposures – 1,000 to 5,000.

• Maximum Total Intergration Time – 30 to 60 seconds.

• Low camera gain.

• Deep red filter.

 

My Typical Performance Results

• Laptop “Limiting Mag” is 15.5 (as viewed visually on the screen).

• Imaging with my 20cm SCT the limiting magnitude for stars is...

  • 1 second exposure – 15 mag

  • 5 seconds – 16 mag.

  • 30 seconds – 17 mag.

  • 15 minutes – 19 mag.

With my 80mm F5 refractor I've recorded stars to magnitude 17.5 during a 6-minute exposure.

A full moon reduces these numbers by ~1.0 mag.

• Deep sky objects – generally can be imaged with some shape or detail to about 13 mag.

• Galaxy Imaging Results...

  • Good results are obtained for galaxies down to mag 9.

  • Acceptable to mag 11.

  • Unacceptable to mag 13.

  • Detectable down to mag 17.

One should limit imaging galaxies to a surface brightness better than mag 22.0.

• Image resolution due to multi-image stacking...

  • Down to 1.0 arc-seconds for deep-sky.

  • Down to 0.5 arc-seconds for planets.