Stuff that occurs to me

All of my 'how to' posts are tagged here. The most popular posts are about blocking and private accounts on Twitter, also the science communication jobs list. None of the science or medical information I might post to this blog should be taken as medical advice (I'm not medically trained).

Think of this blog as a sort of nursery for my half-baked ideas hence 'stuff that occurs to me'.

Contact: @JoBrodie Email: jo DOT brodie AT gmail DOT com

Science in London: The 2018/19 scientific society talks in London blog post

Saturday, 5 April 2014

Optical effects: my "rolling shutter" camera half-captured a flash going off at science event, delighting me

To be honest I'd have thought I'd have seen more photos like this. I understand that the chances of taking a shot like this again are low but given the gazillions of photos taken it seems like someone else would snap something similar, but searching on Google for 'mid-flash' or 'midflash' doesn't bring anything up - maybe I need better search terms.

This photo was taken by accident by me on 16 July 2010. I was at the Royal Institution to celebrate the SciCast awards and generally have a lovely science communication-y time, which I did. SciCast was celebrating the short films, made by children and teenagers in schools, that explained something scientific to a non-specialist audience. It was great fun and inspiring.

I'm not sure what I was trying to take a photograph of as so little of it is in focus, but I was delighted with the unintended outcome anyway.

Apart from the 'ooh that's a bit unusual'-ness of it, what I like about this photo is that it caused me to learn a little bit more about how iPhone cameras and other smartphone cameras work. The image is created by a 'rolling shutter' which scans from one side to the other. This means that one side of the image is recorded before the other one is, and if you're recording something moving fairly quickly then you can get some fantastically odd distortions.

Here's a relatively slow-moving wind turbine on Blackheath which I took on 29 August 2009 during the fab Climate Camp. There was a session on how to make wind turbines and we lowered this one to the ground to have a good look at it before re-erecting it, at which point it started spinning again. I tried to record a video but it looked rather odd.

My iPhone 3GS camera has a CMOS (Complementary Metal Oxide Silicon) sensor, which brings a certain distortion on images - here's a helpful video explaining the difference between CCD (charge coupled device) which doesn't scan.

Thanks to this article (Everything you wanted to know about rolling shutter) on the phenomenon I also found this great video taken from inside a guitar, using an iPhone 4 which has captured oscillations from the strings - note that this is just an artifact, the strings are actually vibrating much more quickly but this is what the sensor has picked up.

Anyway, back to SciCast - the winning video was Gravity, Mass and Weight by Oliver Madgwick who was 17 when he made it, with lego. It's brilliant :)


Incidentally, when you upload a video file to Blogger it shows you the image below while the video is 'rendering' or doing whatever it does for Blogger to be able to display it, thought I'd capture the image for posterity.


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