DJI has created a whole new field of work for photographers. This is drone photography, many of the photographers are trying to improve their skill level, looking to earn money or make a career in aerial photography. The DJI Phantom, Mavic and Inspire drone lines have made aerial photography much easier. However, despite the availability and the growing number of photographers, it is not so simple, and does not preclude understanding the basics of photography. Some basic principles, such as blur and focus types, are often misunderstood. Or maybe it’s just a confusion in standard industry jargon? Maybe.
What used to be more of a craft is now slowly turning into art. Photography is losing its rigid technical boundaries with the advent of digital cameras. Many beginner aerial photographers get confused by the correct old school terminology. Or, they didn’t know her at all.
Drone operators often say: “My pictures are out of focus” when they make a blurry image. The words “blur” and “focus” are not identical; there is a difference between them. For concise and precise communication, the correct terminology should be used.
Suppose you have a photograph that is not as sharp as you intended, not as sharp as it should or could be. Is this the result of blur or poor focus? Chances are, if you’re flying a DJI Mavic or Phantom drone, it’s a blur issue rather than poor focus. Why did this happen and how can it be prevented? Here is the difference between common types of blur and focus:
Difference between blur and focus
- Blur is an effect (or disadvantage) that depends on the shutter speed of the camera.
- The focusing problem comes from the design or operation of the camera lens.
Blur types
motion blur – Motion blur (also “Object blur”) – striped blur (shift blur) of the main subject in the photo, while other parts of the image appear sharp (or vice versa). This can be done intentionally to help tell a story (such as showing movement), or it can be done inadvertently, leading to an undesirable effect.
If a drone operator wants to show the movement of a subject, intentional motion blur is the desired effect and can be created with a relatively slow shutter speed (approximately 1/30 of a second). But if the operator wishes to freeze the subject to prevent subject blur, a faster shutter speed (approximately 1/250 second or even faster) should be used.
This drone photo demonstrates the correct use of motion blur as the photographer lowers the shutter speed to 1/2 second. The subject shows movement (the waterfall is blurred in the vertical direction), while other elements of the image remain sharp.
Camera Blur – Camera blur (also camera shake) – when the camera shakes, you will almost certainly find that your entire image is blurred evenly – from edge to edge. Look closely at it, and you will see that there are no clear points or borders in the image at all. The blur can sometimes take the form of a tiny hook or a double image. For a drone photographer, this usually means that the drone is moving when the shutter is open. The wind may be to blame. This can be corrected by lowering the shutter speed.
In this photo we can see random unintentional blur caused by camera shake, at a 1 second exposure while the shutter was open, the camera got a lot of movement. Streaks in an image are a sure sign of blur caused by camera movement, not poor focus. The whole frame looks a little out of focus, a closer examination of the image across the frame reveals that the camera was shaking slightly for 1/30th of a second.
zoom blur – Zoom blur is a less common type of blur that can be achieved when the aircraft is flying forward or backward by using a slower (slower) shutter speed. Zoom blur can give a good effect if used properly.
Zoom blur can be used effectively as an artistic technique. The aircraft must fly towards or away from the intended object, while using a slow shutter speed. In the example, a 2 second exposure was set on the Mavic Air camera. Elements that are closer in the scene will be more blurred than elements at a distance (an effect created by a wide-angle lens).
Focus types
Good (correct) focus – the subject of the photo is in focus (correct focus), we often say that the photo is “very sharp”, regardless of the state of the other element in the foreground or background.
Out of focus – the main subject of the photo is not too sharp. The camera lens is focused on the wrong area of the frame. Depending on which DJI drone you’re using, you may have manual or auto focus options. For example, the Mavic 2 Pro allows you to choose between touchscreen autofocus, continuous autofocus (AFC), and full manual focus. A great way to get the subject in focus is to touch the display device by placing the green focus frame on the area you want to sharpen. Then, while flying, press the shutter button halfway to refocus (green area) over and over while moving the aircraft.
But drones are not limited to the DJI Mavic and Phantom lines. It is actually quite difficult to capture an out-of-focus shot with small drones. Generally, if your subject is more than three meters away from the drone, it will be in focus if you use the AFC (Continuous Auto Focus) mode. If the subject is closer than three meters to the aircraft, you will need to focus by touch or by hand using focus assists such as Focus Peaking or Manual Focus Assistant in the DJI GO 4 app.
If you are using a DJI Inspire, you have a choice of lenses. Wide-angle lenses have a large depth of field by default. If you choose a longer (long throw) lens, precise focus becomes more important as the depth of field becomes shallower.
Shallow depth of field – The subject is in focus, but the foreground and background are out of focus. This is often a highly desirable effect used to highlight an object and draw attention to it. The effect is quite difficult to create with small drone cameras like those on the Mavic and Phantom series. As a rule, a longer focal length lens is required for obtaining, with a fully open aperture, which allows you to get a shallow depth of field. For example, this image is easier to capture with an Inspire X5 camera with a 45mm Olympus lens (small telephoto), 1.8 aperture open – imagine photographing a house through out-of-focus tree branches.
The lighthouse is out of focus in this image, and background elements are sharp. This was caused by a shallow depth of field (wide open aperture and close subject distance). Focus could be transferred to the lighthouse simply by focusing with the tablet screen.
Great depth of field – Some problems with poor focus can be solved by using a smaller aperture (ƒ8-11.). A small aperture creates a large depth of field, but this can lead to other issues related to correct exposure. By closing the aperture, you reduce the amount of light entering the matrix, and therefore this method is only suitable when shooting in the daytime, otherwise you will have to raise the sensitivity (ISO), which will increase the amount of noise and reduce detail.
Other factors that affect image sharpness include: lens resolution, sensor resolution, lens cleanliness, micro-scratches on the lens, filter quality and cleanliness, moisture condensation on the lens or sensor. Atmospheric haze and glare issues are also sometimes confused with focus issues.
Original article: djiphotoacademy.com