Lens Flare

Everyone will have taken photos and seen unusual rays or spots if the sun is in the image frame or close by. An example of this is the image I’ve just taken of the sun, with my mobile phone, looking out of my window where there are multiple different rays of different brightness.

There is a good article on Wikipedia on lens flare which explains how the effects are the result of how light is scattered by the multiple lens in a camera.

Now we’re all used to having a camera (or multiple cameras) with out mobile phones, but lens flare also impacts very expensive cameras like the one on GOES 17. I couldn’t identify the exact cost of the camera, but the cost of the programme to build, launch and operate 4 GOES satellites is approximately US$11 billion!

Whilst looking through some recent GOES 17 full colour images I noticed this example where there is a distinct lens flare at the bottom right of the image. This was taken when just about all of the area covered is in darkness, other than the area near Antarctica.

Zooming in on the image, you can better see the flare detail.

However when you do some simple image processing on the image, stretching the levels to highlight the detail you get a surprise!

Instead of just one flare, you’re also seeing a second one plus a large splodge of light too.

Thinking in 3D, with the sun being south of the equator as we’re still in summer, just, in the southern hemisphere, this really is sun light that is causing the lens flare.