6 Things You Need to Know for Long Exposure by Filter

Landscape photographers often use long exposure to blur movement. For this series of photos I used a ND64 filter to achieve a long exposure with my Phantom during (late) daylight. The photos are made at two different waterfalls in Iceland. The new Phantom 4 Pro and Inspire 2 give you even more possibilities.

1. Long exposure

Long exposure
Aperture2.8       Shutter Speed1.6      ISO100       TypePhantom 3 Professional/ND64

With a long exposure (or slow shutter) photo you will blur any moving objects like waterfalls, waves or city traffic. At the same time, stationary elements like rocks or roads will remain sharp if your camera is stable enough. With moving water this gives a kind of mystic or serene effect.

For long exposure photography you need ‘less light’. For photography on the ground, this can be achieved by the lowest possible ISO, a smaller diaphragm (higher F value), photographing around sunset/sunrise or attaching a neutral density (ND) grey filter. You will always use a tripod to avoid any movement of the camera.

A Phantom or Inspire is sometimes referred to as a flying tripod. It is really amazing how all technique works together to hover the quadcopter in place as good as possible, while the gimbal does the rest in achieving a perfectly still image. On Skypixel we have seen great long exposure photos, but they are often made after sunset or during the dark night. With a Phantom 3, Phantom 4 standard or Inspire 1, ISO can go no lower than 100 and the diaphragm is fixed to F2.8 so you cannot use them to achieve a longer exposure. So we need to wait till it is dark enough and/or use a filter.

2. ND filter

PolarPro ND64 filter
Aperture2.8     Shutter Speed1.6       ISO100      TypePhantom 3 Professional/ND64

A neutral density (ND) grey filter will reduce the amount of light coming to the sensor of your camera. ND filters are sometimes used by drone pilots while filming to smooth out the video in bright light conditions. However they are also useful in still photography to achieve longer exposure times. I use the PolarPro ND64 (available for Phantom 3, Phantom 4 standard and Inspire 1). The ND64 reduces shutter speed by 6 stops. This will not be enough in bright light in the middle of the day. About half an hour before sunset however, I could achieve shutter times of about 1 or 2 seconds while some areas were still lit up by the sun.

3. Hold still

Hold still
Aperture2.8       Shutter Speed1.6       ISO100       TypePhantom 3 Professional/ND64

While making long exposure photos, it is very important that your flying camera doesn’t move at all (unless you want to capture the movement to get an overall blurred image). After you move your drone to another position or turn it around and release the control sticks, it automatically brakes to stop the movement. Then the drone and gimbal stabilize at its current position. This process may take one or a few seconds (at least with the Phantom 3). If you watch closely at the corners of the image on your tablet or smartphone you will notice some slight movement that will blur your overall image. So after repositioning I always wait a few seconds until the image is totally still, before I take the photo. At the other side, don’t forget to wait until the exposure has finished before you start moving again.

4. Low ISO

Aperture2.8       Shutter Speed1.3       ISO100       TypePhantom 3 Professional/ND64

In most cases I recommend to photograph at 100 ISO (or lower if possible), to get a longer exposure as well as less noise in your image. You probably have to set the exposure to manual, because otherwise the camera will increase the ISO. This also means you have to check and adjust the exposure time before every photo. You may use a slight overexposure to achieve a slightly longer exposure time, but make sure to retain detail in the lightest areas. Photographing in RAW will give you more possibilities for a lighter exposure because more details are conserved.

5. Double shots

Double shots
Aperture2.8       Shutter Speed4.5       ISO100       TypePhantom 3 Professional/ND64

Even though the quadcopter and gimbal will do a great job together and many photos will be sharp, it’s a good idea to make a long exposure photo twice (without moving your camera in the meantime). If one of the photos is blurred at places where it should be sharp, you still have another one. For your most important photos, you may even want to make several more – just to be sure. The same applies when flying in windy conditions or with exposure times longer than about 2 seconds.

Making every photo twice has another advantage. If you find out later that a longer exposure would have been better, you can achieve it afterwards. By blending two separate photos (taken at exactly the same spot) together in Photoshop, you effectively achieve a twice as long exposure time. This results in an even more blurred image. The image above is blended from two photos (2 seconds and 2.5 seconds), so the result is similar to a 4.5 second single exposure.

6. Phantom 4 Pro / Inspire 2

Phantom 4 Pro / Inspire 2
Aperture7.1       Shutter Speed0.6s       ISO200       TypePhantom 4 Pro/ND16

The new Phantom 4 Pro and Inspire 2 (with X4S camera) have an adjustable diaphragm from F2.8 to F11. This gives much more flexibility. On F11 (4 stops light reduction) you may be able to achieve long exposure times without a filter around sunset/sunrise (although sharpness may decrease a bit at F11).

The ND64 filters will not fit on the Phantom 4 Pro and X4S. However, for the Phantom 4 Pro DJI sells a ND16 filter (4 stops) and PolarPro produces a ‘Cinema series’ filter set including a ND32 (5 stops) for Phantom 4 Pro and X4S. The ND32 combined with F11 gives a total light reduction of 9 stops (compared to F2.8). With 9 stops reduction you can achieve long exposure times earlier on the day, or even longer exposures (up to the maximum of 8 seconds) before sunset.
Thank you for watching!

Author:Paul Oostveen
Article From:SkyPixel
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