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 Astronomik 12nm Ha Filter clips into my Canon EOS Rebel camera body to capture the Horsehead Nebula in only the hydrogen alpha wavelength. This is an excellent option when shooting on a night that includes moonlight. As an added benefit, clip-in filters like this can be used with a camera lens as well.
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