Many hours of exposure, and even more processing time went into this one. I started with 240 minutes and went up from there. With every additional hour, more of the fainter areas showed up. 540 minutes in, the small faint galaxies surrounding M101 started to pop out. I enjoyed processing this image, but it was somewhat difficult, as I couldn't get a satisfying noise reduction/detail balance. I ended up with 8 different versions of the same image all looking slightly different, with only one exception where HDR was not applied for the core. After feeling that all of my processing on this was still lacking, I gave up on this data for a couple months. In the meantime I became more familiar with Pixinsight's ATROUS wavelet and MultiMedian Transform techniques, which allowed me to go back and more gently reprocess this data. This result is a combination of Pixinsight and Photoshop processing.
4/19/16 Update; I have explored some new techniques on how to control the star sizes using MaskedStretch. I love the result, as stars are much improved, showcasing the target more. I have also found some new Pixinsight tricks on how to control the background a bit better. The color looks a bit excessive, but I like the effect on this photogenic galaxy. This is probably version 13 by now, having reprocessed this image on and off since last November. This will be my final version for a while.
Imaging telescope: Vixen VC200L astrograph f/9
Imaging camera: QHY9M CCD
Filters: Orion 2'' RGB
Mount: Astro-Physics AP900 GTO
Other: Meade DSI guider, Robofocus
Software: CCD Commander, Maxim DL, Photoshop CC 2014, Pixinsight 1.8, Adobe Lightroom 5
Dates: L:13,14,15,16,17,18,19,20,24 May,2015 RGB: 13,14 May,2015
Exposure: L: 540' RGB: 5x600'' each, bin2
Total integration: 11.5 hours
Location: Hocking Hills, Ohio, US
Click image for full version and prints.