The Secret for Supersizing the Moon
(This image is not a composite)
I once saw a picture of an oversize moon above the Golden Gate Bridge; beneath the picture someone had commented that the image was obviously was faked because the moon isn’t that big. Though I didn’t scrutinize the picture, I suspect that the commenter’s accusation was right, but for the wrong reason.
While some photographers take the easy (and deceptive) approach and just plop a huge moon into their beautiful scene, the mere presence of a large moon doesn’t mean that the image is a fake. In fact with the right equipment and a little preparation, any photographer can photograph the moon large in their images (without cheating).
Most people understand that the longer the focal length, the larger the moon will appear in an image. But focal length is only half the equation, a fact that becomes clear when you take the extreme telephoto approach to the limit and attach a camera to a telescope. True, with a telescope you’ll achieve the maximum enlargement possible, but you’ll also end up with the moon and nothing else—you could capture the very same image whether you’re standing on a tropical beach, atop a towering peak, or in the comfort of your own backyard.
Size isn’t everything
Rather than simply photographing a large moon, what we landscape photographers really want is a moon that appears large relative to the rest of the image. And while the size of the moon in your frame is determined by the focal length, its size relative to the landscape has nothing to do with the focal length.
The moon’s extreme distance means that it will appear the same size to our eye (or lens) regardless of our location on earth. We can enlarge the moon with optics (a lens or telescope), but not by moving closer (without a rocket). On the other hand, the perceived size of earthbound objects changes dramatically with distance—move closer and things get bigger, move back and they get smaller.
So, if the perceived size of the moon from earth is constant, but earthbound subjects shrink with distance, you can make the moon look larger compared to earthbound subjects foreground by moving back and shrinking the foreground—then, once you’re farther back, you can use a telephoto to enlarge everything.
Understanding this makes it easier to see why the moon looks so small in most images because the photographer was too close to the subject: The closer we are to the scene we’re photographing, the shorter (wider) the focal length required to include all of the scene in the frame, and the wider our field of view, the smaller the moon will appear in the scene.
A little preparation
I’m always on the lookout for prominent subjects that can be photographed in the east or west (where the moon will rise or set) and from a great distance. Whether it’s an iconic subject like Half Dome or Mt. Whitney, or an anonymous but striking subject like a hilltop oak, I make a mental note of its location and the vantage point, then figure out when the moon will be on the line connecting them.
I’ve been plotting the moon for far longer than we’ve had computer and smartphone apps that do the heavy lifting, and I still enjoy doing it the old fashioned way, combining topo software with moonrise/moonset tables that give the altitude and azimuth. But if I were starting today, I would probably be using one of the many available apps, like The Photographer’s Ephemeris or Photo Pills (there are others).
It’s also important to understand that a full moon (more or less) rises at sunset and sets at sunrise. So unless there’s no terrain between you and the moon, the full moon will not be visible when the sun is above the horizon. The best time to photograph the moon in the east at sunset is the day before it’s full, and in the west at sunrise is the day after it’s full. You can read more about this here.
The two images above were taken from the same location (at different times). The size of the moon relative to Half Dome is the same, but in one image I shrank the scene and enlarged the moon with a telephoto; in the other, I widened the scene and shrank the moon with a wide angle lens. To get the wide scene and the large moon, I’d need a vantage point with the same angle of view, only much farther back (sadly, that vantage point doesn’t exist).
The story of this image
Armed with this knowledge, I’m on constant lookout for distant subjects that stand out against the east or west horizon. This oak tree in the foothills west of Sacramento has been on my radar for awhile—for years I’ve noted it from the road, but was always on my way somewhere else and never had time to hunt for a vantage point that would work for the moon.
One evening I found myself with a little extra time when conditions changed and a planned foothills shoot didn’t materialize as hoped. Instead of heading straight home, I spent the hour or so of remaining daylight searching west of this tree for a vantage point that would align it with the upcoming moonrise. (Not only do I need a distant enough view that puts the tree against the sky, that view needs to align with the rising moon.)
Back home I did a little more plotting with my topographic software and came up with a tentative plan, and on the evening of the full moon I made my way back up to the foothills. I knew about where the moon would rise, but because I don’t know the exact altitude (in degrees) of the hillside from my planned location, I couldn’t be sure exactly when the moon would appear. (That’s not a problem once I’ve photographed a moonrise from a location, like Yosemite.)
Unfortunately, I got hung up by traffic that sapped all the extra time I’d factored into my plan, and ended up arriving at my location right at the beginning of the window when I thought the moon might appear. I started extracting and assembling my camera, lens, and tripod with one eye on the east horizon and did a double-take when I realized that the moon was indeed coming up. It was just slightly downhill from (west of) the tree, so I grabbed my gear and sprinted east a couple of hundred yards until they were aligned.
I used my Sony a6000 with my Tamron 150-600 lens (Canon-mount with a Metabones adapter). I maxed the focal length to 600mm, but since the a6000 is a 1.5 crop sensor, my effective focal length was 900mm. I quickly focused on the moon, metered, and started clicking. I used ISO 400 to speed my shutter and mitigate micro-vibrations that can be easily magnified at such a long focal length.
The tree was about a mile-and-a-half away. If I hadn’t been so rushed I’d have probably stopped down to f/11 or f/16 to ensure more depth of field (the hyperfocal distance was over 7,000 feet), but fortunately, focusing on the moon at f8 did the job. In Lightroom I cropped the image slightly (less than 15 percent) for framing and to enlarge the tree and moon a little more.