Here is another image of NGC2174, known as the Monkey Head nebula in Orion. David took this with his 8″ f6 Newt. and his new cooled monochrome ASI2600 camera!

He used a binning of 2. This means each pixel in his final image combines the photons from 4 pixels in the array – the image is halved in resolution, but the exposure can be 4x shorter to get the equivalent brightness). He combined 3 images, each one taken through a different filter:  SII,  Ha, and  OIII for a total exposure time of 542 min (9h and 2 min). This is the famous color palette used by Hubble telescope imagers, where SII (Sulpher-II) is mapped to red,  Ha (Hydrogen Alpha) is mapped to green and OIII (Oxygen-III) is mapped to blue. 
The image was processed in PixInsight and Photoshop.

You can compare this version of the Monkey Head Nebula with Sergey’s visible light (RGB) version here.