Making a Barn Door Tracker with a G12

Is this possible with a G12 (using CHDK)?

I have found simple instructions on making a Barn Door Tracker w/out using a motor.

I am still puzzled about shutter time and actual movement of the dial on the tracker. I know that focal length dictates the timing of turning the dial, but am I turning that dial to raise the tracker while the shutter is open? (ie, set the shutter to be open for 5 minutes, every 30 seconds turn dial 180 degrees, if so, how do I avoid shake or movement?)

I was years ago when I used one but I think I used a 50mm lens and left it open. I turned it by hand and I don't remember any problems with shake. I am pretty sure you don't want to do it for more than about ten minutes though.

kezug wrote in post #13084092
I am still puzzled about shutter time and actual movement of the dial on the tracker. I know that focal length dictates the timing of turning the dial, but am I turning that dial to raise the tracker while the shutter is open?

Not sure I understand you, but the rate at which you turn the dial is fixed, whatever focal length lens you are using. Turning the dial compensates for the rotation of the earth, and this doesn't alter, whatever lens you use. However, the longer the focal length, the more likely that innaccuracy in construction and shake/tripod movement will affect the shot. If you have a 50mm lens then you should be OK. Most of the barn door designs I have seen are based around turning the dial one revolution every minute while the shutter is open. They are designed this way so that a sweep second hand on a watch can be used to judge exactly where the dial should be at any time. EXAMPLE HERE

Good luck and please do post your results!!!

Thanks, I am going to make one soon and will post results when I do.

I guess its a matter of more reading and experimenting. I just know that now when I do 30 seconds or so, I get trails. So if I am waiting 1 minute to turn that dial, I am still thinking I will get some trail in there.

I am also thinking that with exposure times of 5 minutes, that my ISO can be much lower and perhaps my aperture much higher?

Turning the dial should be a continuous operation. Your hand is like a motor and the motor should be turning all the time, like the sweep second hand on the watch.

Thank you for that explanation as I just didnt quite make that connection (feeling dumb now).