And now for something completely different. I wanted to try some star trails photography but my (Panasonic Lumix) camera only does shutter speeds up to 8s – which is not long enough.
So I needed multiple exposures, time-lapse style.
I tried a cheap remote release time-lapse gadget but it didn’t work, so I pressed my Raspberry Pi, Pixie, to give up barometry and take up photography. Key to it was a diagram I found at
http://www.doc-diy.net/photo/remote_pinout/ and my PiFace interface. I developed a wee python 3 program to use the relays for shutter release every 20s and set Pixie to start it as a service at boot time. Then I connect Pixie’s relays to the camera and a power supply to Pixie’s MICRO USB input.
Here’s an image of my camera on a tripod, with Pixie ready to go.
And a close up of Pixie and its PiFace interface.
You can see my wee circuit board handywork, with the necessary resistors, strapped to its side. Actually the whole lot fits quite easily in the outside pocket of my usual camera bag.
I set up my camera in the garden and left Pixie to take 1 shot every 20s. I did not attempt to point at the pole star (couldn’t see it anyway) – just wanted to see if I would get anything at my maximum possible exposure f2.8 for 8s at ISO 400. I couldn’t see anything through the viewfinder – so I just went to bed. Pixie and the Camera took photos for about 2 hours before the camera battery gave out.
Then I used a good free image stacking program I found called Startrails and this is the result:
I only used the first 162 images because the quality of later ones was even worse (mist on lens ?) but I am quite pleased with this as a first attempt. The brightest trail is Mars I think and the three-dashed diagonal bottom left must be a plane – it only appears in 3 images, 8s exposures, 20s apart. The orange sky is the lights of Glasgow of course.