Shoot the Moon

A fun photography challenge is to create photographs with a nice bright moon in them.  With a little bit of planning, good weather, and some luck it is possible to make a nice photograph.  I discuss some tips here on how to “shoot the moon” and end up with decent images.

Clouds are not helpful in this photography quest.  This is especially true if they are front of the moon as they scatter the moonlight and make it difficult to avoid a washed out image.  Clouds next to moon, where the moon has a clear sky window from your perspective are great though.  If the weather calls for partly cloudy, go for it, if the weather forecast is for widespread thin clouds or overcast then it might be better to stay home.  Before I head out for moon photography I check the weather satellite maps to look for clear areas — clear where I will stand and clear where the moon will rise.  After many hundred plus mile drives chasing moonrises, only to arrive to clouds, I have learned to adapt and go where the forecast is for clear skies.  Even a thin cloud layer messes things up.

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Moonrise over the Sangre de Cristo in New Mexico with some very thin clouds.  In this photo, “Trampas Peak Eclipse”, a penumbral eclipse, where the moon rises in the outer shadow of the Earth, worked out ok given the clouds — but only for a moment in time.  Once the clouds shifted slightly the moon was washed out due to scattering from thin clouds.

The next challenge to address is due to physics, and can be mitigated in most cases.  Lets say you want to have a sharp image of a bird in front of the moon, while also having the moon be in sharp focus.  To achieve this requires careful consideration of these three variables:

  1. The distance to the bird in the foreground — the “subject distance”.
  2. The focal length of your lens.
  3. The aperture of your lens.

The closer your subject distance is, the smaller the aperture you need for a given focal length lens.  There are some combinations where it is impossible to have both the foreground subject and the moon in sharp focus.   I see this whenever someone tries to photograph an owl on tree branch at close range with the moon behind the owl.  The owl is in focus, and the moon is not, or vice versa.

Physics comes to rescue here with the concept of hyperfocal distance.  This is one-half the distance from you are standing to where your focus your camera (on the bird) where everything from hyper-focal distance to infinity (the moon) is in focus.  The hyperfocal distance depends on the three variables above and can be calculated using optics formulas — or a handy app like DOFMaster.

The definition and concept of the hyperfocal distance is shown in this figure.  It is important to take this into account when photographing a subject in the landscape (tree, bird, etc.) and also wanting the moon to be in focus.  The hyperfocal distance calculation here is for a full frame camera, with a 600 mm lens at f/16 focussed on a subject at 2000 feet.  Note that if the subject was closer, (e.g. 1000 feet) it would be impossible to have the subject in focus and the moon in focus with a 600 mm lens at f/16. (From DOFMaster)

After years of photographing wildlife with the moon in the composition I know follow some simple rules of thumb.  If I am using a long lens (400 mm focal length or longer) I want to be at least 200 meters from the subject and will stop down the aperture to f/16 or smaller.  The hyperfocal distance is strong function of the subject distance!  If you close to subject it will be much harder to get a sharp focus on the subject and the moon.  If you are using a long lens, you need to stop down the aperture, or move farther away from the foreground subject.

For birds flying in front of the moon, say at a wildlife refuge, position yourself far (often a mile or more) from approximately flight paths you see birds flying.  Position your tripod and camera to focus at the distance you see the birds flying, and then align the moon in your field of view — remembering the earth and moon are moving — you will need to keep repositioning the moon in your field of view.

Canada Geese fly south in front of the moon rising over the southern flank of Blanca Peak.  Photo taken from Monte Vista NWR.  In this case I focused on geese flying at a long distance from me (2 miles or more) and then repositioned my field of view to include the moon — then waited for geese to fly into the frame.  Canon 1DX with EF 600 mm f/4L II lens + 1.4 x III at 1/800 sec, f/11, ISO 400 on a tripod.  Note in this case the hyperfocal distance was closer to me than the geese (good!) — so the geese and the moon are both in focus.

Getting the exposure correct for moon photography is difficult when you want to include the landscape in your composition.  On a full moon the moon may be orders of magnitude brighter than the dark landscape.  In order to get good contrast between the moon and the sky it is best to photograph the moon just as it is rising and there still some blue in the sky (the blue hour) and enough light on the landscape to illuminate it.

Some tricks include taking multiple exposures to cover the dynamic range of the moon with the landscape, and timing your moon photography well.  Some good apps for finding moon phases and timing include:

Shoot in RAW format and check your exposure by spot metering on the moon, and then on the landscape.  Compare the light meter readings in your camera and try to find a balance between the two.  When the moon is high and bright, and the night is black, it is next to impossible to get good exposure in both the landscape and the moon — unless you combine many different exposures.

Moonset over Sleeping Cranes, Bosque del Apache National Wildlife Refuge

Why does the moon look so big in some photos?  Is it “photoshopped” ?

The angular size of the moon is 0.5 degrees — always!  There is a very small “enlargement” of the moon’s apparent size due to refraction in the atmosphere as it rises, but this is not the reason it looks so big when it rises.  When compared to objects in the landscape (mountains, trees, etc.) the moon looks huge when it is rising.  When you take a photograph of it using a long focal lens the size of the moon relative to the angular field of the lens can be large.  The moon is 0.5 degrees in angular size no matter what lens you look at with.  If the lens you are using has a small angular field of view (like a soda straw) then the moon will look huge in that lens’s field of view.

Frequently these days I see “composite” images where a photograph of the moon is superimposed onto a different photograph.  At this point the photographer is taking full artistic license and the image they present is not real in the sense that the scene did not look like that as they looked through their camera lens.  Each person has their own style and ethics… I prefer to only present real images — in the sense they are not composites of moons or other objects taken at different scenes — and I prefer the photographer disclose what they did.  A few times I have investigated images of the moon, or Milky Way, that I too wanted to photograph, only to learn later they were not real.

Moonset Over the San Juan Mountains,  San Luis Valley, Colorado

To wrap up, watch out for clouds on the nights you want to photograph the moon.  Try to photograph the moon when it is a low angles and there is still some light on the landscape.  Use a tripod, and pay close attention to the hyperfocal distance if you want to get a sharp focus on the foreground and the moon.  Check your exposures for an over-exposed moon and under-exposed landscape — as the moon gets higher in the sky it is more difficult to get a good overall exposure with just one image.

Three things cannot be long hidden: The Sun, The Moon, and The Truth
   —- Buddha

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