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Sunday, June 22, 2014

paint the sky with stars

What you see above is the combined result of more than 100 sequential photos of the sky I snapped from our front lawn late last night. I'd stumbled across the technique of star trail photography while reading up on light painting at a very helpful site and wanted to try it for myself.

My camera was pointed at what I guesstimated to be the southern pole star after a brief search on Wikipedia. I consulted the digital compass on my phone, managed to locate the southern cross and worked out where to train the lens. I had some difficulty achieving focus - autofocus was useless in the dark and so were my eyes but I did the best I could and started the sequence. I included a bit of the neighbours' half-built garage in the frame for perspective.

For those of you who are interested in the technical details, the settings on my camera were:
Lens: good ol' 18-55mm at wide angle
Programme: Tv with shutter speed at 30"
EV: -2
WB: Auto
Aperture: f = 4.0
ISO: 100
Format: RAW

According to what I read, I needed about 30 minutes worth of photos to produce a decent star trail photo. My arithmetic being what it is (I flunked maths in matric), I worked out that I needed 100 exposures of 30 seconds each, giving me more or less half an hour. Stuff and nonsense, of course. After some time I started wondering why it seemed to be taking so long and did the sum in my head again. To my disgust I discovered that 100 exposures would give me 3000 seconds worth of shots, or 50 minutes.

One third through the endeavour a stupid aeroplane hove into view. There was nothing I could do while the asthmatic thing slowly made its way across my entire shot. I had to remove three photos from the sequence to get rid of the invasive trail of light it left, which caused an almost imperceptible gap in the star trails.

So I spent more than an hour in the wintry cold while my camera did its thing. To keep from freezing I chain-smoked while The One plied me with an endless supply of steaming coffee. It was really good to go back inside when the sequence was complete. It took another hour of so of tweaking and merging in Photoshop using a very handy free script to produce the end result.

I'm really proud of the final photo. It documents how our planet hurtles through space at breakneck speed while we serenely go about our daily lives.

Written by I