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Planning Equipment Optional Equipment Setting the Camera Flight Path Shooting the Photographs Photographing From Commercial Airliners OBJECTIVE With aerial photography, like most photography, you want to take a well-composed, sharp photograph of the intended scene, your photographic “target”, without distractions or confusion. Here is how to do that. PLANNING Do your planning on the ground. Believe me, after a few hundred hours of aerial photography, I know for a fact that it is ten times easier to plan on the ground than in the air! First, know the objectives of your aerial photo project; in other words, what is your target? Things look a lot different from the air, so work on the identification of your target: study maps (air, road, topography), get landmarks in mind, take GPS (Global Positioning System) readings if you can, ask pilots for help. In other words, do everything you can that will help you to find your target from the air. You may have driven up your own driveway for twenty years, but there’s no way to read street signs from a thousand feet and none of the usual landmarks look the same, either. Consider the lighting you want for your photo. If the photo requires lots of overall detail with little emphasis on aesthetics, then midday lighting is best. With the sun up high, shadows are at a minimum. Overall the lighting effect is rather flat, but not much detail gets lost in dark shadow. In fact, a day with a high and evenly-spread cloud layer can work, as long as you don’t need an altitude higher than the clouds. If you’re looking for a more beautiful photograph, then the lower slanting light of morning or late afternoon gives a dramatic look from the air. Analyze which sun angle you want on your target to plan for the best time, within limits, of course. A client once asked me for a photo of the south-side front of his building, and he wanted the sunset behind it, to the north. I can afford to wait for good weather for an aerial photo, but would have to wait a long, long time for a northern sunset! The format for aerial photographs can be either vertical or oblique; vertical photos are shot exactly straight down - a fairly technical assignment - so this article will discuss just the oblique photo which is shot at an angle to the ground, much like looking out from a hillside to the valley below. Oblique aerial photos come in two formats: one format includes the horizon at the top of the photo, the other doesn’t.
Before the flight, establish the best possible communications with your pilot - get on the same track. Study maps together, discuss air speed, headings, and altitude. If possible, a previous aerial photo of the same area can be of great help. During actual photography from the air, agree ahead of time that you will give directions for the flight on everything that does not compromise safety. I can’t ever recall having overdone preflight planning with a pilot. You are completely responsible for the preflight check of your own equipment. Be sure lenses are clean, film or digital cards/batteries are loaded, and lens hood and filter are firmly attached. In short, make sure all of your camera equipment is working. Some additional concerns for your aerial photography preflight include: Tape your lens focus at infinity or apply the infinity setting to your digital camera if possible. Tape down knobs, such as shutter speed or settings dials. In the noise and sensory overload conditions of an airplane cabin, it is surprisingly easy to bump knobs or other settings on your camera and not notice. Use a haze filter to help remove some of the blue cast that comes from shooting through a lot of atmosphere. Also, a polarizing filter can increase contrast and give very pleasing results at certain camera angles and times of the day. If you’re just starting out though, twisting that filter while trying to maintain the target in your viewfinder is just one more detail in an overloaded work environment. Especially in the beginning, keep things as simple as possible. Back to the top of the page
EQUIPMENT A quick and simple checklist of the minimum you need to take aerial photos: Camera—film or digital, 35mm is fine unless you want the bigger enlarement options of a medium format film Lens—zoom is ok if it is a professional lens; high quality at low cost can be obtained with fixed focal length, such as 50mm or 90mm lenses Camera strap—keep that strap around your neck! A loose camera out the window is both expensive and dangerous. Film and/or Digital Supplies—Slow speed film (50-100 ISO) for midday sunlight or if you have a fast, professional lens; Medium speed (200 ISO) for point-and-shoot type cameras or cloudy bright conditions; Fast speed (400+ ISO) for low light or if you won’t enlarge prints much beyond 8x10”. Take two to three times the film you think you’ll need. For digital, take a spare digital card or two, plus plenty of batteries. Battery life is significantly reduced with cold temperature, such as from the open window of an airplane. Aircraft—most airports have flight instruction and rental operations that you can hire. Many have introductory flights at a reduced rate and won’t mind you bringing along a camera. Cessna airplanes are readily available and make a good camera platform because of their high wing and windows that open. Pilot—I have flown in the past as a pilot. For aerial photography, I have thought about piloting again, briefly. However, I am primarily a photographer, which is job enough up in the air. So while I concentrate on getting the best possible aerial photograph, I leave the best possible job of flying, navigating and safety to the pilot. It’s a good combination and always adds a comfortable level of safety while in the air. Occasionally I get to take the controls while the pilot sets the GPS or consults the map for the next target. But we each have our specific focus that works well to get the job done. Pilots of U-2s and SR-71’s might also be taking the recon photographs, but they have a few million dollars of autopilot, radar and automatic camera equipment to back them up. Lacking that, I prefer the assigned duties covered by two people – one pilot and one photographer. Aircraft rental companies will often provide a pilot, usually an instructor. Don’t be shy to ask how many flying hours your pilot has or how familiar he is with the local terrain. An experienced pilot with whom you can easily communicate is your best asset for aerial photography. Back to the top of the page
OPTIONAL EQUIPMENT Spare Camera—don’t waste an expensive flight and all that time if something goes wrong with your camera. Take a spare on every flight! Haze and Polarizer Filters—filters help to cut the blue cast and increase contrast, especially at high altitudes. Lens Hood—Also helps to increase contrast and avoid lens flare when the aircraft wing is not shading the camera from the sun. Electrical tape—seems like up in the air, there is always something to tape down. On your camera, electrical tape removes easily without leaving a sticky residue. Duct tape works, too - I usually have several small pieces already cut and sticking to parts of my camera bag. Back to the top of the page SETTING THE CAMERA Exposure—For manually setting the camera, the “Sunny 16” rule works well for most hours of a sunny day in the air. That rule says to set your lens f-stop to f16 and your shutter approximately to the film speed. For example, with 100 ISO film, your setting is f16 at 1/125th second shutter speed. Of course, 1/125th is too slow for aerial photography, so swap f-stops for shutter speed, e.g., f11 at 1/250th, f8 at 1/500th, f5.6 at 1/1000th and so on. I consider 1/500th the slowest handheld shutter speed and prefer 1/1000th for aerial photos. Remember, the airplane is vibrating, the ground is moving, and, often enough, you’re shaking. In conditions other than blue-sky sunshine, before takeoff, take a light meter reading on the ground, either an incident reading by pointing the meter up toward the sky or a reflected reading using neutral gray such as the runway cement or a neutral gray card if you remember to bring it. Then set your camera accordingly. The light exposure reading from the air can usually be trusted over mixed terrain if you are at low altitudes. Over 2000 feet, depending on atmospheric conditions, your camera’s built in meter can give worse exposure readings than what you measured on the ground. When in doubt, bracket exposures. I prefer transparency (slide) film and usually bracket one stop under and over the selected exposure. Over a dark forest or a bright wheat field, your camera’s reflected exposure reading can be off by a stop or two, so trust “Sunny 16” or your on-the-ground meter reading. Once again, you don’t need depth of field at 1000 feet or more above the ground. Try to find the “sweet spot” where your lens has its best resolution and then use that f-stop with a film speed and shutter combination that allows you to shoot at 1/500th or faster. Whether auto or manual exposure, get out the tape and stop those camera dials from moving. If it can move, tape it down! I’m amazed at how a camera seems to have a mind of its own in the air and ends up on settings that I never intended.
Lens Focus Unless you’re in a helicopter flying very low, flight rules will keep you at 1000 feet or higher for most aerial photography. For all intents and purposes, that’s infinity on your lens focus. So tape your lens barrel at that setting. I guarantee that if you don’t, you will come home with out-of- focus pictures because the lens changed focus due to vibration or bumping or whatever airborne gremlin it is who delights in twisting that barrel! If your lens is autofocus, the camera may have trouble focusing on the rapidly moving earth beneath you. Best approach is to set it to manual focus and just tape it down (have I mentioned tape before?). Some point-and-shoot type of camera are really deficient at focusing on moving objects – if your camera does not allow a manual focus setting at infinity, you might want to test it from a moving car first to see how the autofocus acts on distant objects out the window. Lens Focal Length For many years, I have done 95% of my aerial photography with fixed focal length lenses (also called prime lenses) of 35mm, 50mm and 90mm on my 35mm Leica M6 or with corresponding focal lengths on a Hasselblad 6x6cm. Once in awhile a telephoto of 200-300mm on an 35mm SLR would be needed to isolate a single house from the air. Zoom lenses that cover some part of the 28-200mm range are useful and handier than prime lenses. However, high quality zoom lens with fast f-stops are expensive. You get more bang-for-the-buck with prime lenses. If you need to zoom, just ask the pilot to “go ‘round” again a little closer or farther away. Back to the top of the page
Fill the frame while maintaining relationships around the target.
• Don’t stab at the shutter release (use rifleman’s
technique - breathe and squeeze). •
At altitude, try using the little round window at the rear galley
of some commercial airplanes – it is often fairly clean and
scratch free.
GET STARTED The complexity and methods of aerial photography can fill a whole book just for how to shoot oblique photos. Vertical aerial photography leads to even more complexity covered by topics such as Photogrammetry and Remote Sensing. But for getting started, the ideas in this article cover most of the basics and should help you with that unique pictorial perspective called aerial photography. Be safe and have fun. |
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ABOUT THE VERTICAL FORMAT PHOTO: Shooting straight down on the landscape gives a perspective that can be helpful for planning or mapping. However, many people have a hard time understanding what they are looking at from the vertical angle. Also, for a hand-held camera, it requires some special aerial maneuvering to get the camera pointed absolutely vertical. I rely on a special camera mount in the airplane, which keeps the camera vertical while in normal, level flight, and also allows for a series of vertical shots that can then be scanned and stitched together with “panorama” software on the computer.
Since I am not actually looking through the camera viewfinder on vertical photo flights, careful preflight planning is also required. In this case, for proper ground coverage, I calculated altitude for the lens/film size combination, gave the pilot specific flight path information (GPS points, heading and speed to fly), and then took photos every 15 seconds as we traversed the Samoa Peninsula located between the Pacific Ocean and Humboldt Bay. The six photos cover about two miles on the ground as required by my client, an engineering company. The final digital photo was over 350 megabytes and clearly displayed detail down to the yellow stripes on the highway.
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