Posts: 5
Threads: 1
Joined: Oct 2015
Posts: 5
Threads: 1
Joined: Oct 2015
This is one of my first time-lapse efforts using a telescope; I made plenty of mistakes. It was an unusually balmy September evening in Minneapolis, and I set up two telescopes at the edge of a city lake, one to let the public see a close-up of the moon, the other to let my Canon 60Da take pictures every ten seconds through a Televue-85 refractor. The mount was only very roughly polar aligned, and it only had a sidereal tracking rate, so it needed to get re-centered often.
I captured the moonrise with auto-exposure on and manually compensated the exposures and aligned the frames in Photoshop. The sequence was assembled at 10 frames/sec. This was obviously too labor intensive to apply to the lunar eclipse sequence, which I wanted to run at 30 fps, so I searched for tools and found LRTimelapse. It has been a steep learning curve, but it allowed me get the exposure levels mostly right.
The next challenge was to align the lunar images and remove the tracking drift and re-centering movements. I have not found a suitable tool for this yet, so I wrote a Matlab script to find the circular outline of the moon and center it in each frame. It works when the image is not corrupted by clouds, but suffers when there is image noise present. I don't like having to leave camera raw to do this however (I converted to tiff for this stage).
I really wanted to show the moon moving into and through the Earth's shadow. To do this, I needed to identify the size and location of the umbra, and then do some precision cropping to keep it in a fixed position in the frame. I would have liked to use LRTimelapse for this, but I don't think it allows cropping (and in-painting) to areas outside of the current frame.
https://vimeo.com/142082712
This has been a lengthy but valuable exercise. I hope to have a few more practice runs on lunar eclipses over the next few years.
Regards,
Thor.
I captured the moonrise with auto-exposure on and manually compensated the exposures and aligned the frames in Photoshop. The sequence was assembled at 10 frames/sec. This was obviously too labor intensive to apply to the lunar eclipse sequence, which I wanted to run at 30 fps, so I searched for tools and found LRTimelapse. It has been a steep learning curve, but it allowed me get the exposure levels mostly right.
The next challenge was to align the lunar images and remove the tracking drift and re-centering movements. I have not found a suitable tool for this yet, so I wrote a Matlab script to find the circular outline of the moon and center it in each frame. It works when the image is not corrupted by clouds, but suffers when there is image noise present. I don't like having to leave camera raw to do this however (I converted to tiff for this stage).
I really wanted to show the moon moving into and through the Earth's shadow. To do this, I needed to identify the size and location of the umbra, and then do some precision cropping to keep it in a fixed position in the frame. I would have liked to use LRTimelapse for this, but I don't think it allows cropping (and in-painting) to areas outside of the current frame.
https://vimeo.com/142082712
This has been a lengthy but valuable exercise. I hope to have a few more practice runs on lunar eclipses over the next few years.
Regards,
Thor.