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Because of my job I take lots of photos of people and wind turbines. This means photos outdoors, lots of contrast, and no option to arrange people. I take what I can get. I use a combination of smartphone, point-and-shoot, and a mirrorless MFT Olympus (the best camera is the on you have in your pocket).

I've just come back from a trip and found that lots of my pictures have ghost turbines in them - they look like double exposures because the rotors of the turbines appear to be rotated slightly, but are much fainter. Because the blade tips are moving about 80 m/s, I think the ghosting is separated by maybe 1/10 of a second, maybe more. The image below is a zoom in to the area where the turbines are.

Why are there ghost blades visible in this image?

This photo was taken with a 2-year old smart phone. The exposure is f/2.25 1/3571 4.235 mm ISO50.

What is happening, and how could I avoid this in future?

I also recently bought an Olympus OMD E-M10 mark III with stock 14-42 mm pancake. I've not noticed this happening with that camera, but would like to know how I could avoid it - with that camera I generally try to use smaller apertures and keep exposures as short as possible, but what else can I do?

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    Possible duplicate of What is a rolling shutter? When do I have to be aware of it?
    – scottbb
    Mar 20 '18 at 12:45
  • @scottbb - thanks! But what's the solution? Is there one? Mar 20 '18 at 12:50
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    Can you include a photo in your question? -- With shutter speed.
    – Rob
    Mar 20 '18 at 12:51
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    Damn. This is embarrassing. It's actually a cellphone picture that got lumped in to the library. Exposure time was 1/3000 or so, but I'm not too bothered any more - the solution is "use a real camera". I could change the question though to reflect the correct camera? Mar 20 '18 at 13:05
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    @AndyClifton Both phone cameras and "real" cameras can demonstrate rolling shutter effects. "Real cameras" have been doing it for over a century.
    – Michael C
    Mar 20 '18 at 13:08
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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.

  1. 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.

  2. 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.

  3. Buy a camera with a global shutter, which reads the whole sensor at once, such as most CCD sensor based camera.

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  • Thank you for the concrete suggestions of how to mitigate the effect. 1. might push me towards having to schlepp a tripod around, though, so 2 seems more realistic at this time. Might need a brighter lens, though... And 3. might have to wait until I have a good excuse! Mar 24 '18 at 10:29

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