Why do wind turbine blades show faint doubled positions in photos, and how can I prevent it?
Asked 3/20/2018
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I often photograph people outdoors around wind turbines using a smartphone, compact camera, and an Olympus OM-D E-M10 Mark III. In some phone photos, the turbine blades appear twice in slightly different positions, like a faint double exposure, even though the image isn’t motion-blurred. One example was shot at f/2.25, 1/3571 sec, ISO 50. What causes this effect, and how can I avoid it on phones or mirrorless cameras?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
8y ago
2 Answers
4
it sounds like what you are expercing is the effect caused by rolling shutter used in modern day CMOS sensors. The effect happens when the blades move faster than the sensor can read out the image. The sensor reads line by line, and the blades have the opportunity to move past the sensor multiple times during the readout, creating the artifacts. Here is a nice youtube video explaining the effect
There are couple ways that you could remedy this.
You could use a slower shutter speed. A slow shutter speed should allow for the blades to show up as blurs rather than as artifacts/distortion, which may be more preferable.
You can try shooting at the maximum shutter speed which may allow for faster sensor readout speeds. Depending on how fast your blades are moving it could freeze them with less or no distortion.
Buy a camera with a global shutter, which reads the whole sensor at once, such as most CCD sensor based camera.
Originally by user74133. Source · Licensed CC BY-SA 4.0
user74133
8y ago
0
Generated from our catalog & community — verify before relying on it.
This is most likely a rolling-shutter artifact, not true double exposure. Many phones and other CMOS-sensor cameras read the image line by line rather than all at once. If turbine blades move significantly during sensor readout, different parts of the frame record the blades at slightly different moments, which can create faint shifted blade positions or odd distortion.
Ways to reduce it:
- Use a slower shutter speed if possible, so the blades blur smoothly instead of showing distinct ghosted positions.
- Or try the camera’s fastest shutter / capture mode, which may also use a faster sensor readout and reduce the effect.
- Avoid modes that combine multiple frames computationally, if your phone offers a more basic single-shot mode.
- Your Olympus may show it less simply because its readout behavior is different.
You usually can’t eliminate rolling shutter completely on devices with line-by-line readout, especially phones, but changing shutter speed and shooting mode can make it much less noticeable.
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