Sunday, July 26, 2015

Rainbow in infra-red

Most usually, when processing infra-red photographs, they are converted to black and white; basically because infra-red doesn't have any colour that we can see. In black and white, white means lots of infra-red, and black means little or none - it's a convenient representation of something we can't actually see.

However, our cameras have sensors that capture light in three channels; red, green and blue. Even values of infra-red radiation get captured in these three channels though infra-red wavelengths have very little red and no green or blue at all. So, when we process an infra-red picture, it is still made up of red, green and blue data and, if we produce a picture from these three channels of data, it is usually known as a 'false colour infra-red' - which can look quite unnatural; hence why black and white is often favoured.

However, when a rainbow appeared today, I wondered how it would show up if photographed in infra-red and the colour channels were retained. So, because every man woman and child in the world are dying to know the answer to this question, here it is:
Rainbow over Oxford - false colour infra-red photograph

Saturday, July 25, 2015

3 out of 3

Our third and last geocache on this sunny winter afternoon found us at the start of the Lees Valley Road. A smart walk uphill (goodness, I made it!) and Bethany found the little capsule hidden behind a large rock.

Fortunately, I had 'Irene' (the InfraRed Canon A590) in my pocket, as I felt that the play of light and shade on the folded hills would come out well in the IR spectrum which, I think, it did.

Canon A590 IR, 1/80 sec, f7.5, ISO 80, 60mm efl.
No, the white isn't snow; just the tussock reflecting the IR. So, with the light and the temperature both fading fast, we decided not to venture further along the road but headed home to light the fire and settle down with a warm cup of tea.