In all honesty, the term “Best” when it’s applied to focal length in order to capture Killer drone photos, is sort of like asking what is the “Best” sunlight to grow tomatoes in, or what is the “Best” air for a human to breath who sufferers from Asthma. Much like air and sunlight, Focal Length just has to exist, and its a matter of its supporting camera settings and how they’re complimenting it, that make it ‘the best’.
Focal Length compliments.. Or, is complemented by (however you want to look at it) variables like; Aperture, ISO, and Exposure Time. Together these variables create the Art of Photography. Drone Photography is no different. The ability to harmoniously bring all these variables together in one image is what makes it ‘Killer’. The difference between the ‘Novice’ Drone Photographer and the ‘Seasoned’ one, is the ability to accomplish this harmony with every snap of the camera. The skill of evaluating what is in the camera’s frame and adequately manage these variables to create the best image takes practice, it’s not something you can read in a book, or watch a YouTube video about, it’s about doing and oftentimes learning through failure.
What is Focal Length Anyway?
Focal Length is a calculation of an optical distance from the point where light rays converge to form an image.
A lens’ focal length tells us the angle of the view—how much of the scene will be captured—and the magnification—how large individual elements will be. Dan, at Shuttermuse.com has a great post on Angle of View vs Field of View, seen here. The longer the focal length, the narrower the angle of view, and the higher the magnification. The shorter the focal length, the wider the angle of view, and the lower the magnification. According to Wikipedia a shorter focal length bends the lights rays more sharply, bringing them to a focus in a shorter distance.
Look at this image, see how the 24 mm catches more of the foreground and less of the subjects. This is most certainly a shorter focal length and a wider angle of view. In fact, it’s hard to tell from this shot what or who the subject even is. But, with the 400 mm, considered a longer focal length, it’s very apparent who the subject of the photo is, but it’s hard to tell what’s around them.
How are Focal Length and Aperture used to capture ‘Killer’ Drone Images?
Aperture is the amount of light that is allowed to make it to the camera’s sensor. The diaphragm is the part of the camera that facilitates how much light passes through the lens and onto the camera’s sensor. Here is an illustration of various camera apertures. As you can see, an aperture set at F1.4, will allow a lot of light to hit the sensor, while F32 will let very little.
My drone, the Mavic 2 Pro, has a ‘Prime’ Lens with a focal length of 28 mm. This means the distance from the lens to the camera’s sensor is 28 mm, and because it’s a ‘Prime’ lens this distance cannot be changed. A healthy human eye sees objects at about 35 mm, so the 28 mm is about the distance of the human eye.
If all I have to work with is 28 mm, what do I do on really bright sunny days?
Glad you asked…
Even though my focal length is fixed, I can still minimize the amount of light that passes through the lens to the sensor. Lowering the Aperture to an F11 or F16 on bright days will better control the amount of light in your image.
Now, I know, if you’re anything like me when you fly your Drone there seems to be a lot going on. You’re trying not to hit anything, you’re watching your battery-life, and making sure you maintain a strong signal. Throw adjusting camera settings in there, and you’ve really complicated things. One thing you can do to minimize the stress, is set your drone to Aperture Priority Mode prior to liftoff, which is the ‘A’ in the camera settings. See Here:
For an in-depth post on Aperture Priority Mode, read this great post from Chris at Photofocus.com. This will simplify things a bit and allow you to concentrate solely on the aperture of the subject your shooting, and the rest of the photographic adjustments can be handled by the camera’s internal metering.
Flying During Civil Twilight
Remember, according to Section 107.29 you have 30 minutes after dusk to fly your drone, which means you’ll likely need to make some adjustments to your aperture settings in the opposite direction to account for the lack of light.
How shutter speed and focal length complement one another
Typically with longer focal lengths, you need a faster shutter in order to avoid the dreaded blur from camera shake. Like this:
Taken with my Mavic Pro at 28 mm, the one on the right ended up “on the cutting room floor”. The one on the left is much less ‘Noisey”. 1/500th is a reasonably fast shutter speed which helps to freeze the water flow, creating a cleaner, crisp image.
How to choose your Drones Shutter Speed:
The general rule of thumb to get the sharpest picture, free from the effects of camera shake, is to use a shutter speed which is at least as fast as 1 divided by the focal length of the lens. So in the case of my 28 mm Mavic 2 Pro’s ‘Prime” focal length, I would set my shutter speed to be at least as fast as 1/28th of a second. But, if you’re Drone has a zoom lens, and the Mavic 2 Pro does have a model with a Zoom Lens, then set your shutter speed to be (1 over the focal length you are set at). For instance, if you’re zooming in to a focal length of 50mm lens you want the sharpest picture you can get, then set your shutter speed to 1/50th of a second. Tom at Tomstechtime.com, has a great post and video on Drone Shutter Speed and what you can do with ND Filters to augment the ISO, Shutter speed, and the Aperture.
I’m still learning to be a better photographer and drone pilot, and I look at it as an evolution. It’s not something you can accomplish in a month. Like being a good Guitarist, it takes years of practice.
This is one of the reasons I started TheDroney, I wanted to be better at both flying and photography. I’ve always loved photography, and drones just made my love for it grow. This site helps me understand and learn the art of photography a little more, with each and every blog post. Thank you for visiting my site, I hope to provide you value every time you come back to visit.