Wednesday, October 7, 2015

Crescent Nebula with Color Calibration

I used the Spyder3 device to calibrate the monitor on the laptop.  I found that there is a very small cone for viewing where the calibration appears good to the eye.  The off-axis performance of the screen is lacking.  Now that this has been done, I can at least confirm colors.  The contrast is not so great, so I am unable to properly evaluate functions of noise reduction and clipping.  Thus, these tasks must be done on a separate system or on a different display.

In the meantime, I reloaded the files into PI and did the ColorCalibration step again.

This fixed a lot of the green color cast and made the pictures look much better than they were before.

I can see that there are big problems in the dim areas of the sky where the noise reduction dropped off too much data.  Also, I had a heavy hand on histogram stretching, clipping many of the stars.

For what it's worth, here are the modified images.

Crescent Nebula GSSP 2015 - Version 1

Crescent Nebula at GSSP 2015

A first pass through the data, as noted earlier.

Crescent Nebula at GSSP 2015
This was completely processed on a laptop with an uncalibrated monitor.  Wow.  The colors are completely skewed.

I'll have to calibrate and redo the processing to fix it.  I can see that working on the laptop is not going to be practical for any color-critical work.  Also, the NR steps have been too drastic.

Lesson learned.

Tuesday, October 6, 2015

Digital Data from GSSP 2015

During GSSP 2015, I used a the QSI camera with the SV4 to image a familiar target.  I knew that there would be a limited amount of night to use, so I wanted to get the most from the super-dark skies of the area.  Thus, my target was the Crescent Nebula.

I'd imaged this target before at GSSP in 2012.  At the time, it was a real challenge and I struggled with chasing squiggly lines all night.  Last year, I didn't worry about it and went after different targets.

With the new camera, I wanted to return to the target and see what I could get with a different tactic.

The weather posed a challenge of course.  Green data is a little thin, with only a few subs for integration. On the nights I wanted to get Ha Continuum data - the clouds didn't cooperate.  In the end, I haven't used the Ha Continuum data yet, so I may end up removing that filter from the mix.  At the moment, though, it's a good filter for using to test star images.