The Horsehead Nebula with a Modified Canon T3i
The Horsehead nebula is by far one of my absolute favorite targets to shoot with my DSLR. This winter deep-sky object lies in the constellation Orion and contains several interesting features that make it stand out in sky full of wonders. From a light polluted backyard in the city, capturing a faint emission nebula like the Horsehead Nebula requires patience and perseverance. The use of narrowband filters (In this case, Ha filter), can dramatically improve your results.
Barnard 33 – The Horsehead Nebula
RGB: 2 Hours, 40 Minutes – Ha: 1 Hour, 20 Minutes Ha
Total Integrated Exposure: 4 Hours
Camera: Canon EOS T3i (600D) Modified
Telescope: Explore Scientific ED102 CF
Mount: SkyWatcher HEQ5 Pro SynScan
Guide Scope: Orion Mini 50mm
Guide Camera: Meade DSI Pro II
Guided with PHD Guiding
Stacked in Deep Sky Stacker
Processed in Adobe Photoshop CC
I have chosen to frame the Horsehead nebula to include the Flame nebula as well. This is a popular orientation for this area of Orion.
I shot the original RGB data of the Horsehead nebula from the backyard on December 6th, 2015. I have always wanted to photograph this iconic subject, but winter weather conditions and limited time have kept me from imaging this area until this past December. I did not capture nearly enough data for a smooth, detailed portrait of the area, but good enough to start poking around with.
More data in 2016, this time in Narrowband H-Alpha
I returned to the Horsehead Nebula in late November 2016. This time, with a new telescope and a new primary imaging camera! I took advantage of some late fall clear skies in the backyard and collected as many RGB exposures as possible on this DSO. I kept the same orientation as the previous version but decided to scrap the frames captured using the 450D. I set my modified Canon Rebel T3i to take 3.5-minute exposures through a Hutech IDAS LPS filter.
The narrowband Hydrogen Alpha exposures ignored almost all wavelengths of unnatural light and produced a detailed monochrome portrait of the area. The filter I use with my Canon Rebel T3i is an Astronomik 12nm Ha clip-in filter. I shot several 4-minute exposures totaling 1 hour and 20 minutes in total. After stacking the Ha exposures in Deep Sky Stacker, I combined the final version with the RGB data to create a HaRGB Composite. This method can produce incredible portraits of deep-sky nebulae like the Horsehead Nebula, even from bright skies in the city.
The Horsehead Nebula in H-Alpha:
A lot of processing was needed to produce the final version of this photo. The ultra-bright star Alnitak makes processing the image a challenge. The brightness of this star can be easily blown out and take over the image. Russell Croman’s Gradient Xterminator made removing the horrible gradient issues the original image had a breeze. The rest of the processing was several iterations of level and curve adjustments, as well as a few actions from Noel Carboni’s Astronomy Tools Action Set. Some of my favorite actions to use include:
- Increase Star Color
- Local Contrast Enhancement
- Less Crunchy, More Fuzzy
Adding H-Alpha to the image
The addition of Ha data using the Astronomik 12nm Clip-in filter on my Canon T3i helped immensely. This filter helps to create more contrast between the nebulosity and the background sky. Using a ha filter on your DSLR adds a new dimension to your existing RGB (regular color) images. Here are a few of the benefits of combining Ha with existing RGB images:
- Improved contrast and detail in nebulosity
- Cuts through heavy light pollution
- Smaller, sharper stars