Wednesday, May 21, 2014

Intervalometer and the stars

I periodically get an email newsletter from Make Magazine. In a recent issue Ron Risman had an article about how to take time-lapse pictures of the stars. You can find the article here. I thought it would be fun to try, but I don't have a digital SLR camera. As luck would have it, my brother Jim does, and he was coming down to Florida for a long weekend a couple of weeks hence. He brought his camera down and we thought we'd give it a try.

Just to manage expectations, we don't yet have any pictures worth looking at. We followed the guidance in Ron Risman's article, but realized we needed an intervalometer. Now I didn't actually know what that was but Jim educated me, saying that is was a device that could trigger a camera at specified intervals, hence the name. Further he explained that his Olympus camera had an infrared receiver that could be used to trigger the shutter using a hand-held remote, which he didn't own.

We jumped on the internet and found some work by jmknapp that used an Arduino microcontroller and an infrared LED to emulate the remote. That information can be found here. As it turns out, I had an Arduino microcontroller and an IR LED. I quick downloaded jmknapp's software, and made a few little changes so it would trigger the shutter of Jim's camera at intervals we could set.

And here it is. Ok, I know, not much to look at, but this is the proof-of-concept stage. We didn't get this all done until the last evening that Jim was going to be down here. We took a few pictures, changed some settings, took a few pictures, etc. The moon was just into its second quarter so it was bright enough to wash out the pictures, and it took us a while to get the focus right, but we were closing in on it.

Since Jim left I have been working on improving the user interface and functionality and here's what I have.

For testing purposes I have temporarily replaced the IR LED with the red one you can see in the picture so I can see if it's working with the unaided eye.

As you can see I added a Delay feature so Jim can have it wait for a specified number of hours/minutes/seconds before it starts taking pictures. I also let him have it stop taking pictures after a certain amount of time or a certain number of pictures.

I also added another mode. I included a Passive Infrared sensor (PIR). Jim gets lots of deer and other wildlife in his yard, and in PIR mode the camera will be triggered by motion in its field of view.

The semi-circles at the bottom of the screen are indicators of the sensitivity of the PIR, which can be adjusted via a knob.

All that's left to do it put it in some kind of case, but I thought it would be good to test it in the field first. I'll be going up to Chicago in a few weeks and we'll try it out then. I'll post any time-lapse videos that are worth looking at.

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