Exposure Bracketing with the DJI Mavic Pro

February 15, 2017  •  1 Comment

The DJI Mavic Pro is impressive, but there's no getting around the fact that the tiny camera has some serious limitations. It may be have a Sony sensor in there, but size still matters when it comes to photography, especially for landscapes with dramatic lighting. The smaller sensors like the one in the Mavic just don't have the dynamic range of larger sensors like the ones in APS-C and full frame cameras. For reference, the 1/2.3" sensor in the Mavic Pro measures only 7.66 mm diagonally compared to 28.2 mm for an APS-C sensor or 43.2 mm for a full frame camera sensor. The full frame sensor is 28 times bigger, so it can gather 28 times the amount of light! On top of that, the Mavic is a moving platform, so the challenges to image quality and sharpness are even greater. However, as the image below shows, this camera is still capable of capturing some incredible images although a little extra work is required to get to the final result.

4 shot HDR, manual bracketingLightroom HDR composite of 4 images To work around the limitations of the small sensor, exposure bracketing is a must when capturing scenes with high dynamic range so that details are retained in both the highlight and shadow areas and image noise is reduced. I've been doing some testing with my Mavic Pro to get an idea of what the camera is capable of and how to best use bracketing to get the highest quality images out of the camera.

First off, I don't recommend using the built-in auto exposure bracketing (AEB) with the camera in auto mode. In this mode, the brackets are captured by changing both shutter speed (good) and ISO (not so good). While this may be beneficial in some cases, such as in windy conditions, increasing ISO has the effect of increasing noise and reducing dynamic range producing images with less detail (see test here). So it is really counter-productive to capture a set of images with reduced image quality in an attempt to get better image quality. You will get a better image from the bracketed set than from a single photo, but it won't be as good as what you can get with just a little more work. And although the app shows a difference of 0.7 EV for each exposure frame in the set, it is really only 2/3 EV, so the total exposure range goes from -1.31 to +1.31 EV.

For the next test, I looked at using AEB in manual mode so that only the shutter speed changes. The good news is that it works, but with the same limitation of only covering about -1-1/3 EV to + 1-1/3 EV which is really a limited range to cover when the sensor is already challenged. For this test, I started with a base exposure at about -1 EV because the bright part of the sky was so bright in the frame. The image below was the result; AEB worked well for this image, but the sun was excluded from the frame so the total dynamic range of the scene was more limited.

5-shot HDR, AEB in manual modeLightroom HDR composite of 5 images Because of my concern about only getting an effective range of 2-2/3 stops out of a bracketed series of 5 shots, I did another test wherein I manually changed the exposure to capture 5 shots with a step of about 1 EV between shots. Except that I only captured 4 images instead of 5 and overshot the third exposure by using the on-screen exposure guide rather than my head! I intentionally included the sun in the frame to really test the capabilities of the camera sensor. Even with my mistakes in capturing the brackets, the 4 shots created a really nice HDR composite with clean highlights, even around the sun, and greatly reduced noise.

The first image in this post shows the final result; the two images below compare the HDR composite to the base exposure. Although the top image (base exposure) has good detail and low noise in the foreground, there is no detail in the bright area around the sun. Also notice the very apparent noise in the darker clouds in the upper left part of the image. And this is with a healthy dose of Noise Reduction applied in Lightroom! Compare that to the lower image and you will quickly notice how much better the composite is, particularly in terms of preserved highlight detail and reduced noise.

Base exposure, 1/30 secondBlown highlights and no detail in the sun, lots of noise in the darker clouds 4-shot HDR compositeDetailed highlights and much less noise

So my recommendations would be to use 5-shot AEB in manual mode for most shots. To ensure the highlights are not blown, start with a base exposure of about -1 EV using the dial on the right side of the controller. For scenes with greater dynamic range, such as a sunrise/sunset with the sun in the frame, either capture a set of 5 bracketed shots manually with about 1 EV difference in each shot, or shoot 2 sets in AEB and adjust the exposure by 1 EV between the sets. For either of these methods, start with a base exposure of 0 EV and decrease for subsequent shots. And, always shoot in RAW!


Comments

John Mitteco(non-registered)
I'm having issues in AEB with the Mavic. As you said, In Auto mode, it not only changes the Shutter Speed of the exposures but it also changes the ISO throughout. Degrading the image.
This is also happening in Manual Mode with Shutter Speeds 1/4 second or slower in low light situations.This shouldn't happen in Manual Mode.
Pretty bummed out about it. Hard enough being without Aperture control, so trying to do all these work arounds that aren't working.
Manually Bracketing the exposures is almost impossible with any wind at all.
Any ideas?
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