I wish to click Star Trails using my Canon SX130IS. I've installed CHDK but am facing some issues like below:
1) CHDK settings are punched in the camera while the lens/sensor is off. Once the settings are punched one needs to push the "Click" button to start the camera working as per the settings entered in chdk.
When shooting star trails generally an object is kept in foreground and I doubt that the focus will be on this object instead of the stars due to the DOF issue.
2) When taking pictures using slow shutter speeds, equal time is taken in processing the image. Hence a 1 minute shot becomes a 2 minute shot. During the 1 minute when the camera is processing the image, earth rotates a bit and hence when the camera captures another 1 minute shot the stars are in different position. Due to this the star trails aren't continuous but interrupted.
In DSLR cameras there is an option called "Long Exposure Noise Cancellation" which when selected, the camera doesn't process the image for long time and hence the next image is captured almost from where the previous image was left.
Any ideas to overcome these problems?