Photographing the Moon

As I write this, it’s 50 years to the day since a giant Saturn V rocket rumbled off the launchpad to begin the “successful failure” that was the Apollo 13 mission. Amidst a global pandemic at the present time, most of our thoughts are much closer to home and right now we find more in common with the post-mission quarantines that the crews of Apollo 11, 12 and 14 experienced. For beginning astrophotographers, the Moon presents a fascinating target and is one that is relatively easy to explore from your own backyard during our current lockdown. With modest equipment, you can photograph the lunar surface in surprising detail which you can then share with your friends and family on social media. Or why not produce a print?

This tutorial will focus on techniques for those with DSLR/MILC cameras and a telephoto lens to obtain images that reveal the Moon in detail.

The Moon is the first subject I encourage those looking to explore astrophotography to start with. As our closest celestial neighbour, it’s large and bright and allows you to practice techniques that will come in handy when you turn your attentions to the stars in due course. Techniques such as operating your camera in low light conditions, manual focusing, manual camera operation and post-processing techniques (which will be covered in a later tutorial).

Recommended Equipment

• DSLR or MILC camera (fully charged battery, memory card)
• Tripod
• Telephoto (zoom) lens with focal length at least 300mm (full frame) or 200mm (APS-C)
• Cable release/Intervalometer (optional)

Planning

You don’t need to go far for these images, as long as you have a clear view of the Moon for an hour or so, you can shoot it from your backyard. You’ll need to consider the phases of the Moon to start with. Are you wanting to shoot a slender crescent Moon in the twilight hours or are you aiming to photograph the fully lit (as seen from our viewpoint here on Earth) Full Moon? Some of the best opportunities occur in between where the difference between light and dark exposes beautiful relief detail in the craters and mountains dotting the lunar surface. Each day different detail is revealed along the terminator (the line dividing the unlit hemisphere from the sunlit hemisphere) which slowly sweeps across the surface as the lunar cycle progresses. This detail isn’t as apparent in Full Moon images where the light is flat and is the equivalent of shooting landscapes under a harsh midday sun.

The phases of the Moon are caused by changes in the alignment between the Moon, the Earth and the Sun. As the Moon orbits the Earth, the amount of sunlight we see on the lunar surface changes. The start of the lunar cycle is known as the New Moon and this is where the Moon is aligned with the Sun with the Earth and Sun on opposite sides of the Moon. Therefore the side of the Moon exposed to Earth is in shadow which means that we can’t see it as the Sun is too close to it and too bright – incidentally this is why there is no such thing as the “dark side of the Moon” – during a new moon phase, the opposite side of the Moon to the one we see is actually in full sunlight. It’s just that we never get to see that side of the Moon. As the Moon moves through it’s orbit the fraction of the surface that is illuminated by the Sun increases from a slim crescent right through to a full Moon where 100% of the surface facing us is lit. These are known as waxing phases. As the Moon’s orbit continues after the Full Moon phase, the fraction of lit surface reduces through to the next New Moon phase. These are known as waning phases. A waxing or waning crescent Moon is named as such when less than 50% of the Moon’s visible surface is illuminated. First and third quarter Moon’s are named for their timing during the lunar cycle. When between 50% to 99% of the surface is illuminated, these are known as the waxing or waning gibbous phase.

The Moon rises and sets later each day, a bit over an hour from day to day. By the time of a Full Moon, the Moon is rising around the time the Sun is setting. The Moon’s path through the sky is similar to that of the Sun. It rises in the east and sets in the west. When the orbits of the Sun and Moon do perfectly align with respect to our viewing position on Earth, an eclipse occurs.

Once you’ve decided on what phase of the Moon to shoot, you can calculate precise moonrise and moonset times for your exact location. You can do this at timeanddate.com or use an app like Planit! Pro or Photopills. Now you just have to keep your fingers crossed for clear skies!

How to photograph the Moon

Now that you know where the Moon is going to be and at what time to shoot the desired phase, set up in a location that gives a clear view of the required part of the sky.

Tripod: I recommend using a tripod, especially when you’re starting out, but if you don’t have a tripod then you should still get acceptable results with a good handheld technique. Using a tripod allows you to steady your composition and give you time to sort the rest out as you go without having to rush. Set your lens to its maximum focal length and turn off auto-focus and any lens stabilisation functions. Switch to live view on your camera and aim towards the Moon. Your lens will be at its best in the centre so that’s where you should try to keep the Moon to allow you to record the most sharpest details. The Moon will move pretty fast through the frame (the longer your focal length, the faster it moves relatively speaking) so you may need to re-center your composition every few mins or so.

Focal Length: the longer the better! Check out the diagram below to see how much sensor real estate is occupied by the Moon at various focal lengths. With today’s high resolution sensors, heavy cropping will still produce a very usable image for small prints and social media sharing from even a medium telephoto lens.

Raw or JPEG? I recommend shooting raw files to give you maximum control over the dynamic range during processing.

Focus: Autofocus should work for most images of the Moon but the camera’s focusing system will typically work best if the selected focus zone is set on the edge of the Moon as there’s plenty of contrast between the bright moon and darker sky around it – it’s contrast that the autofocus system needs.  If you’re trying to focus in the middle of the moon, there’s probably not enough contrast to allow autofocus to work correctly. You may need to look for a setting that lets you manually choose an AutoFocus Point and pick one to suit. All that being said, I prefer to work with manual focus personally which we’ll cover next.

Confirm the lens is set to manual focus and use live view at maximum magnification to focus on the Moon manually.  Your livescreen view will move around due to movement of you moving the focus ring, bumping the camera etc, but when you take your hands away and the view steadies, you’ll be able to see if you’re bang on.  The outline of the Moon will be crisp, sharp and bright with craters clearly visible if you’re focused, otherwise an out-of-focus image will have a fuzzy appearance. It’s worth spending the time to do this right so don’t be in a rush. If the Moon moves out of frame too quickly, recenter the composition and keep working at it, you’ll get there!

Exposure: When metering for an exposure of the Moon, it’s easy to blow out the highlights. The Moon’s surface is an excellent reflector of sunlight – that’s why it’s so easy to see it. But these highlights, if not handled carefully, will result in an overexposed image with little you can do to recover the little details later. Underexposing by a stop or so will help and I recommend getting comfortable with your camera’s manual exposure mode (you’ll use it for other astrophotography too). Check that your screen is showing a live histogram and set an exposure that protects the highlights (the right-hand side of your histogram). Exposure settings will vary depending on the phase of the moon and the amount of light in the sky. The Full Moon is incredibly bright and you’ll use a much faster shutter speed than if you were shooting a crescent moon.

I typically try to shoot at an aperture of f/8 to f/11 for the sharpest results from my lens with an ISO from 100 to 400. Shutter speed needs to be fast enough to freeze the apparent motion of the Moon and protect the highlights. If your chosen shutter speed is resulting in motion blur, then maintain a correct exposure by opening the aperture a fraction or increasing your ISO.

Shooting Technique: Double-check your focus and composition is correct. If you don’t have a cable release or intervalometer, set a time delay of 2 to 5 seconds to take care of any movement caused by you pressing the shutter button. Stay in live view and increase magnification to maximum. When the Moon is nice and steady on screen, go ahead and open the shutter with your cable release. Review the image checking focus, composition and histogram results. Remember any data bunched up on the right side of the histogram is likely to be data you can’t recover later.

How many images should I shoot? You’ll be surprised at the effect our atmosphere can have on your images. Even on a clear night, distortions in the atmosphere can cause lunar images to appear soft in parts. This is something astronomers call “seeing” conditions and some nights will be better than others. Cold, clear, still conditions are usually best so rug up warm and enjoy the experience! You’re also likely to get the clearest images when the Moon is overhead your position rather than near the horizon. This is because you’re looking through a relatively thinner slice of the atmosphere when you look up rather than towards the horizon. So take multiple exposures, rather than just one, and when you review these on a larger screen later on, check to see how sharp the resulting frames are from one image to the next. Don’t discard any of these frames though, save them and once you get comfortable with the processing, you can learn how to stack multiple exposures to improve the overall sharpness of the resulting image.

Now that you’ve got plenty of images captured on your memory card, you can import them onto your computer and process them to taste.