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Comment by donatj | Hacker News Reader

The most curious part to me is that all these photos of the helicopters were taken by cameras without rolling shutters.

Having serendipitously dipped a toe into the avgeek waters, it doesn't seem so surprising to me. In a major metropolitan area, you can bank on people listening to ATC traffic and camping out near airfields with good-enough cameras at almost any time. In the avgeek world, one can earn both personal satisfaction and kudos for novel aircraft, so they are especially desirable.

Even a beginner is likely to have an imaging system that is plenty good, with a mechanical shutter. The atmospheric shimmer in the third image suggests that it was made with a longer lens; probably not a beginner.

The President of the United States can't fly over Britain on a secret trip without getting photographed by a semi-retired IT manager: https://www.theguardian.com/uk-news/2018/dec/27/air-force-on...

It is really great to see distributed citizen-journalism happening.

It is super cool that there is a community around this

I read that as "disturbed citizen-journalism" and, honestly, it'd still work.

I don't think we can draw that conclusion.

Its the middle of the day with no cloud, so there is plenty of light. That means we can up the shutter speed to the point where rolling shutter is negligible.

I have a nikon d7000, which has a rolling shutter. Its only really noticeable when I'm recording video, or when there is _lots_ of movement inside the shutter time. at 1/3200th of second, thats a lot of movement.

The D7000, like all system cameras, has a mechanical shutter it uses when taking photos. Even though technically ”rolling” as well, it is much faster than a typical electronic shutter due to the way a CMOS sensor must be read out. Phone cameras have no physical shutters and use e-shutter all the time, but your D7000 only resorts to it when shooting video.

As a rule of thumb, it takes several milliseconds for a mechanical shutter to traverse the sensor plane, but it takes several tens of milliseconds for an e-shutter to readout the sensor. Shutter speed does not affect this; even at 1/4000s or 1/8000s or whatever the time difference between the top and the bottom of a photo remains the same.

While that's true, a smartphone even at 1/3200th will have a 30th of a second or so of rolling shutter.

Most cameras that can take good images of helicopters in flight have a mechanical shutter available.

Thats only there to protect the sensor. There will be an electronic shutter too.

Not really. Most interchangeable lens cameras do not have a purely electronic shutter, it's a very new feature.

Those that do, do not have it as the default mode. There is also the electronic first curtain shutter, but that is way closer to a mechanical shutter than to an electronic shutter.

Such as?

Citation needed.

Pretty much every single camera that has interchangeable lenses, and thus can mount a telephoto objective sufficient for taking good pictures of helicopters has a mechanical shutter. From the Sony alpha series, to Nikon DSLRs, to the Canon EOS line, and so on.

Probably taken with cameras with mechanical shutters? That doesn’t seem very curious.

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