M51 Whirlpool + data
Posted 11 January 2013 - 04:15 PM
Taken in the AM hours of 1/9/13 from my driveway in Nebraska
8x 15min subs (took 10, threw out 2)
Captured with Backyard EOS, stacked with DSS, and processed with PixInsight. All details on equipment in sig below.
Stacked and Calibrated TIFF: https://www.dropbox..../Whirlpool 2...
Zip of all data including calibration frames: https://www.dropbox..../WHIRLPOOL 2...
Posted 11 January 2013 - 04:19 PM
Posted 11 January 2013 - 04:23 PM
Posted 11 January 2013 - 06:26 PM
Posted 11 January 2013 - 07:47 PM
I gave the data a go in StarTools:
Posted 11 January 2013 - 08:07 PM
Posted 11 January 2013 - 08:11 PM
Posted 11 January 2013 - 08:32 PM
Re-Processing Workflow: (Instructions here...)
•RAW file Processing in ImagesPlus 5.0
•Align TSR/Combine/Crop in ImagesPlus 5.0
•Digital Development in ImagesPlus 5.0
•Multi Point Flatten Background-Planar in ImagesPlus 5.0
•Multiresolution Smooth-Sharpen (Finest/Fine 30/15) in ImagesPlus 5.0
•Geometric Transform/Scale (Factor 0.4) in ImagesPlus 5.0
•Smoothing in ImagesPlus 5.0
•Saturation (Block), and 'Noise Reduction' in Photoshop Extended CS6
•Star Size and Halo Reduction in ImagesPlus 5.0
•Hue-Saturation-Luminance in ImagesPlus 5.0
•Curves, Brightness/Contrast, Saturation, and 'Noise Reduction' in Photoshop Extended CS6
Posted 11 January 2013 - 09:07 PM
Posted 12 January 2013 - 04:20 AM
Posted 12 January 2013 - 05:12 AM
i think if you take more subs of 8-10 minutes you get better resault.
i forgot to say that the detail on the galaxy is VERY good!!!
Posted 12 January 2013 - 11:41 AM
if you have field rotation though... that's another story.
Posted 12 January 2013 - 01:24 PM
Yea I wasn't really sure on exposure time. I don't fully understand how I can tell when I've captured all the data I can possibly capture and should end the exposure, so I just guessed. I've always assumed longer is better, but I guess that isn't always the case.
Posted 12 January 2013 - 11:14 PM
the whole subexposure length thing comes up again and again. the bottom line is that you just need to expose long enough to get the skyglow to overwhelm the read noise of the camera. for a canon DSLR the rule of thumb is to get the histogram hump's left edge 20-30% of the way across the back of camera display, and you are there.
exposing longer won't kill you (until you saturate the stars of course) but from a mathematical perspective exposing longer won't really help with the so-called 'stacking efficiency'. once you've reached the "skyfog limit"* you're there. using the shortest sub you can get away with = less trailing, fewer subs lost to airplanes, etc.
* this term confuses people but what it means is that your image quality will not be limited by the read noise of the camera but rather by the limiting magnitude of your local skies. if you expose shorter than the skyfog limit, then the light from the faintest stars/objects in your image is destroyed by the read noise - essentially overwritten as the image is read off the CCD. getting to the skyfog limit means that objects dimmer than the sky brightness are simply lost in the sky glow, rather than to camera artifacts.
Posted 13 January 2013 - 01:26 AM
Posted 13 January 2013 - 04:23 AM
Gave it a run through PI
As you say a lot of noise , but still some Data to work with
Posted 13 January 2013 - 03:16 PM
Posted 13 January 2013 - 04:43 PM
Just google, "pixinsight tutorial harry"
He does an amazin job showing the basics, and even with basics you can get some great details out.