The clouds have parted, and I have enjoyed 2 cold, clear nights of astrophotography back-to-back! This is a fortunate occurrence that doesn’t come very often, especially during a Canadian winter. However, the moon is nearly full, rising in the late evening in it’s waning gibbous phase.
This reminds me of a question that comes up time and time again. Is deep-sky astrophotography during a full moon a waste of time? The moon reflects bright sunlight into the sky for about a week on either side of a full moon. This moonlight floods the sky and is so bright that it washes out faint deep-sky objects, both visually and photographically.
Attempting Deep-Sky Astrophotography during a Full Moon
The week surrounding a full moon used to mean a break from imaging faint deep-sky objects. After New Moon, the nights that followed would get me down as the waning crescent moon grew brighter and brighter each night. I knew that my astrophotography adventures would be put on hold for at least 2 weeks.
Images taken under the bright glow of the moon have less contrast, detail and can quickly become overexposed. It is possible to reduce the moon’s effects with careful post processing, but you’ll never capture your best full-color images during this time. For those reasons, the moon kept the cap on my telescope lens.
Not anymore! With the purchase of my Narrowband DSLR H-Alpha filter, I was able to double my time under the stars.
The image above shows the planet Venus over my garage and telescope.
Basking in Bright Moon Glow
I wouldn’t recommend shooting a faint nebula (such as the Bubble Nebula) during the full moon without a narrowband filter. However, it can be hard to disregard a clear night, no matter how bright the glow of the moon is. You can improve your chance of success by shooting objects well away from Earth’s natural satellite.
On January 14th, 2017, my target was a little closer to the moon than I would have liked it. I would not have attempted this deep-sky target had I not been using a narrowband H-Alpha filter.
When the moon is out, I shoot Narrowband Ha. When it’s not out, I shoot RGB. HaRGB composites have proven to be a fantastic option for astrophotography in the city. The filter blocks out the light-pollution us deep-sky imagers are accustomed to in our suburban backyards.
Tips for Deep-Sky Imaging in Moonlight
At a bare minimum, I would recommend a light-pollution filter if you are imaging in the city. The filter I use is an IDAS Light Pollution Suppression Clip-in filter for my Canon DSLR. But what about shooting without any filters, is it a waste of time?
Not necessarily, but there are some guidelines to follow that can increase your chances of producing a quality astrophoto from your imaging session. Moonlit nights are the perfect opportunity to try something new with your equipment.
Here are some ideas to keep in mind when partaking in astrophotography during a full moon, without using any filters in your camera:
Save Nebulae for New Moon, Shoot Star Clusters!
I am personally guilty of neglecting these beautiful targets in Liu of colorful galaxies and nebulae. There are countless open and globular clusters to photograph and add to your collection. In my experience, star clusters are best captured by using short exposures (30 seconds – 1 minute). This way, the bright stars are no blown-out, and you can record sharp colorful stars in your image.
Take Short Exposures
Shooting shorter exposures and stacking them have some advantages over shooting fewer, long exposures. Although the individual frames will not record as much detail on your DSO, the background sky, and stars will be less “intense”. What I mean is, it will be much easier to set the black point while processing your final stacked image, and bright stars will not “take over” as they would in a long exposure of 5 minutes or more.
The signal-to-noise ratio will also improve as you add more subs to your final image. These principals apply to images taken during any moon phase, but are especially effective when dealing with added moonlight.
Enjoy Visual Observing
If you are anything like me, the thought of missing out on imaging time during a clear, moonless night is painful. But with the Moon out, you can enjoy some guilt-free visual observing! The fainter objects will be a challenge, but star clusters, bright galaxies, and planets (and the Moon!) will be unaffected. Take some time to remember why you got into this hobby in the first place.
Filtering out the Moonlight
With so many amazing winter astrophotography subjects currently up in the sky, choosing a target can be a tough decision. I opted for one of the most well-photographed nebulae of them all, the Orion Nebula.
If you read my last post, you’ll know that I consider Messier 42 to be the best deep-sky astrophotography subject for beginners using a DSLR and telescope. Over the years, I have soaked hours and hours of exposure time into this nebula, but this time is different.
This is what the Orion Nebula in Ha (H-Alpha) with a DSLR looks like:
The image above is 32 X 5-minute subs @ ISO 1600 using a Canon Rebel T3i and Astronomik 12nm Clip-In Ha Filter.
As you can see, an incredible amount of detail was captured on this target despite the nearly full moon and heavy light pollution. Using the HaRGB Image processing technique outlined in my latest astrophotography tutorial, I was able to combine this data existing RGB (full-color) images taken back in December.
Here is the Orion Nebula in HaRGB:
I waited far too long to incorporate a narrowband filter into my DSLR deep-sky imaging. One of the main reasons I put this off was a confusion about how these filters worked when imaging with a DSLR camera.
There are 2 types of narrowband filters that can be used with a DSLR camera. The first type is my personal favorite option – a clip-in filter that installs directly over your camera sensor. These are convenient but can be expensive. The Astronomik 12nm Ha Filter was more than $200 after tax and delivery (Oceanside Photo & Telescope). The second type is a traditional type of telescope eyepiece filter (either 1.25” or 2”) that threads into the end of your camera adapter and inserted into the focuser draw tube.
Early on, I thought narrowband astrophotography was reserved for owners of CCD astrophotography cameras. I am delighted to announce that this is not the case. A fellow astrophotographer friend uses the 1.25″ Orion Narrowband Ha filter and has experienced promising early results.
Astrophotography Image-Processing Meet-Up
I recently met with a group of amateur astrophotographers to share our astrophotography processing tips and tricks. It was an enlightening experience, and I learned some great tips for processing deep-sky images using Adobe Camera Raw, and stacking in Adobe Photoshop.
This alternative image processing technique includes pre-processing each frame in Adobe Camera Raw and using the stacking feature built into Adobe Photoshop to produce the final image, rather than DeepSkyStacker.
The noise-reduction, gradient removal, and chromatic aberration corrections were impressive and worthy of some future experiments on my own deep-sky images. This is a valid second option to my traditional image-processing workflow, and I will share my results.
Next Target: The Rosette Nebula
On night 2 of my astrophotography double-header, I changed gears and pointed my telescope towards NGC 2244, the Rosette Nebula. I captured over 2 hours worth of exposures in H-alpha. I’ll share that photo and my processing notes later on this week.
Until then, keep on shootin’.
Discussion: Astrophotography during a full moon (Cloudy Nights)
What’s in the night sky tonight? (EarthSky)
Orion the Hunter Easy to Spot In January (EarthSky)
Current Moon Phase / Calendar (Moon Giant)