March 2021: Orion Nebula in Widefield
Imaging Project
A favorite night-sky target for newcomers to astrophotography is the Great Orion Nebula. This region is a relatively nearby star-forming region in the constellation Orion (arguably the most recognizable constellation in the night sky). This target offers many benefits to beginner imagers as it is an extremely bright and large nebula that doesn’t require advanced imaging setups.
Smartphones have even advanced to the point where some can image this target (although, with varying results)! Seriously, on a clear winter night aim your smartphone’s camera at Orion’s belt and set it to night mode. Snap a picture and see if you spot it!
Orion Nebula with my smartphone in “Night Mode”
Image By: David Brunell
The difficulties in imaging this region comes from the differences in the bright portions and the darker portions. The trick is to get a series of exposures of different lengths and blend the images in post-processing.
Imaging Deep-Dive
Using the William Optics Redcat 51, I plan on gathering a widefield perspective of the Orion Nebula. This will require stacking multiple images of 15 second, 60 second, and 5-minute exposures using the lens and Sony A6000. The purpose of this technique is to build an HDR (High Dynamic Range) image that can show details in the brightest and dimmest areas of a single picture.
The shortest exposures develop the extremely bright stars located in the heart of the nebula. Without using this technique the entire core of the image would be an overexposed mess.
(Advanced note: The shorter exposures also make a great “star reduction” mask. Instead of utilizing the minimum filter in photoshop. Just paint in your target on a layer mask of the shortest exposure. This keeps extraneous stars to a minimum.)
See below for a comparison slideshow of the unedited raw images of each exposure length. Notice how the core of the nebula becomes overexposed rather quickly.
Final Image
Ultimately, I captured approximately 3 hours worth of images of the Orion Nebula. I really enjoyed the widefield perspective of this target, it is important to always leave celestial objects in context. When you crop in the image it’s easy to forget that even a target as large as the Orion Nebula is still a minuscule portion of the night sky.
The humbling feeling you get from seeing objects is half the fun of this hobby and I look forward to sharing more projects with you all!
Orion Nebula and Running Man Nebula
So you want to learn more?
https://en.wikipedia.org/wiki/Orion_Nebula — 10 Minute Read
https://www.nasa.gov/feature/goddard/2017/messier-42-the-orion-nebula — 5 Minute Read with additional amazing images
