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DJI Drone Photography – Blur vs. Focus

DJI has created an entirely new sector of working photographers. These are aerial drone photographers, many of whom are trying to raise their skill level with a yearning to earn a few dollars or establish a new career.  The DJI Phantom, Mavic, and Inspire lineup of drones has made aerial camera placement and operation an uncomplicated process. What is not so simple yet is the basic understanding of photography.  Some of the fundamentals, like types of blur & focus, are frequently misunderstood. Or, maybe this just a confusion of standardized industry vernacular? Perhaps.

What used to be more of a craft is now becoming more of an art. The rigid technical boundaries of photography have become more relaxed ever since digital camera sensors were introduced. Many new and eager drone photographers have muddled up the proper terminology. Drone operators often proclaim, “My shots are out of focus,” when they capture a blurry image. The words blur and focus are not interchangeable; there is a difference between the two. For concise and accurate communication, correct terminology should be maintained.

Suppose you have a photo that is not as sharp as you think it should/could be. Is it a result of blur or poor focus? Odds are, if you are flying a DJI Mavic or Phantom drone, it is a problem of blur rather than poor focus. Why did it happen and how do you prevent it? Here is a breakdown of common types of blur and focus:

The Difference Between Blur and Focus

  • Blur issues and techniques are based on camera shutter speed.
  • Focus issues and techniques come from the camera’s lens.

Types of Blur

Motion Blur (also Subject Blur) – A streaking blur of the primary subject in the photograph, while other parts of the image appear sharp (or vice versa). The can be done intentionally to help tell the story, or by accident, resulting in an undesired effect. If a drone operator wants to demonstrate the motion of a subject, intentional motion blur works well and can be created with a relatively slow shutter speed (approximately 1/30th sec). But if the operator wishes to freeze the subject to prevent any subject blurriness, then a faster shutter speed must be used (approximately 1\250th sec.).

Motion Blur example from DJI drone.
This drone photo demonstrates the productive use of motion blur, as the photographer slows the shutter speed to 1/2 second. The subject is showing motion while the other elements in the images remain sharp.

Camera Blur (also Camera Shake) –  If you are suffering from camera shake you will almost certainly find that your entire image is blurred from edge to edge. Look closely at it and you’ll see that there are no sharp points in the image at all. The blur may occasionally have a tiny hook shape or double image appearance. As a drone photographer, this generally means the drone is moving while the shutter is open. Wind may be the culprit. This can be cured with a faster shutter speed.

Example of camera shake.
An unintended camera blur occurred as the camera moved during the 1-second exposure. The streaks in the image are a sure indicator of blur caused by camera movement rather than poor focus.
Example of camera shake at 1/30th-second.
The entire frame appears slightly out of focus, a closer glance at the image from edge-to-edge reveals that the camera had a minor shake during the 1/30th-second exposure.

 

Zoom Blur – A less common type of blur that can be achieved when flying a drone forward or backward while using a longer (slower) shutter speed. Zoom blur can have a nice effect if used appropriately.

Zoom blur may be used effectively as an artistic technique. The drone must be flying toward or away from the intended subject while the camera is set to a slow shutter speed. This was a 2-second exposure using the Mavic Air. Closer elements in the scene will blur more than elements in the distance (an effect produced with a wide-angle lens).

Types of Focus

Good Focus –  When the subject of the photograph is in good focus, we often say that the photo is “tack sharp”, regardless of the other element in the foreground, or background.

Out of Focus – The intended subject of the photograph is not “tack-sharp”. The camera lens has been focused on the wrong area in the frame. Depending on which DJI drone you are using, you may have options for manual or autofocus methods to prevent this from happening again. The Phantom 4 Pro, for example, allows you to choose between tap-screen, auto-focus continuous (AFC) and manual focus. A great way to achieve consistently good focus is to tap on your viewing device by placing the green focusing box in the area that you wish to be tack sharp. Then while flying, push the shutter release button halfway down to refocus (the green boxed area) again and again as you reposition the drone.

Don’t wring your hands too much worrying about the focus on your Mavic and Phantom drones. It is actually quite difficult to make an out-of-focus photograph with the smaller drones. As a general rule, if your subject is farther than ten feet from the drone, it will be in focus if you use AFC mode (autofocus continuous). Any subject that is closer to the drone than ten feet should be tap-focused or captured with fully manual focus (P4P only) using a focus aid such as Focus Peaking or Manual Focus Assistant in the DJI GO 4 app.

If you are flying an Inspire, then you have a choice of lenses. Wide-angle lenses by default have a greater depth of field. If you select a longer lens, then accurate focus becomes more critical as the depth of field becomes more shallow.

Shallow Depth of Field – The subject is in focus but the foreground and background are out of the field of focus. This is often a highly desirable effect used to isolate and place attention on the subject. The effect is quite difficult to create with a small drone camera like the Mavic and Phantom series. Generally, a longer lens set to a wide open aperture will create this shallow depth of field. For example, this would work well using the Inspire X5 camera with a 45mm Olympus lens (slight telephoto), opened to aperture ƒ1.8 – imagine photographing a house through out-of-focus tree branches.

Example of poor focus on the subject.
The lighthouse in this image is in poor focus while the background elements are sharp. This was caused by shallow depth of field (wide open aperture). The focus could have been shifted to the lighthouse simply by tap-focusing on the FPV tablet.

Deep Depth of Field –  Some poor focus issues can be fixed by using a smaller aperture opening (ƒ8.-11.). A small aperture creates a deeper depth of field,  but this may lead to other issues related to the exposure triangle.

Other Factors Affecting Image Sharpness Include:  lens resolution, sensor resolution, lens cleanliness, micro-scratches on the lens, filter quality and cleanliness, lens or sensor moisture condensation. Atmospheric haze and lens flare issues are also sometimes confused with focus issues.

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Randy & Stacy are DJI’s only officially authorized aerial photography instructors worldwide.

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Authors Randy Jay Braun and Stacy Garlington are co-founders of the DJI Aerial Photo Academy, providing live city-to-city workshops helping attendees to create better aerial drone photographs for work or for play. A current workshop schedule can be found at www.djiphotoacademy.com and on their facebook page.

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