How to create stationary eclipse timelapse w/o tracking sun's movement?

Question

I took a timelapse of the 21 Aug 2017 solar eclipse. I did not have the ability to track the suns movement so every ~15 minutes I adjusted the camera position.

I want to create a timelapse that emulates tracking. Essentially I want to "cut" the sun out of each individual frame and stitch together where the only movement is the moon across the sun (as opposed to the sun across the frame). I just don't know where to begin.

Are there any automation tools that are designed for this purpose?

Thanks to the community in advance!

Answer 1

This can be done with most video editing software with an aptly-named feature called tracking. It does not always work perfectly but can be very effective and should be quite accurate for your purpose.

First you will need to create your time-lapse as usual. The sun will move across the frame with jumps for every time you moved the camera. Once you have your time-lapse, load into a video edition S/W.

With the tracking tool, select the object to track - in your case the sun - and let the process run. It will take several minutes, producing a track of control-points and the video will be anchored to those. Play the video to see where it lose tracking and, if so, adjust the control-points manually. The intermediate points will automatically follow for smooth tracking.

It is possible that each time you moved the camera, software tracking will stop. In that case, you must run the tracking tool again from the first frame where tracking is lost. Repeat as needed until the video is smooth.

Answer 2

Don't know if there are automatic tools that would work - DSO stacking programs expect to track several stars, planetary stacking ones expect similar planetary detail, so something like an eclipse probably isn't going to work too well with either type.

However, it should be fairly easy to do by hand in something like photoshop (or any editor that allows multiple movable layers with variable transparency).

Just load the first picture in, move the sun to a central position, then repeat the following:

-load the next picture in as a new layer on top of the existing ones.

-make the new layer partially transparent (so you can see the layer underneath) then move it so the sun is in the same position as the layer underneath.

-make the new layer fully opaque again

When you've done that for each picture, you should have a set of separate layers that line up.

Now, you can go through and make each layer visible on its own, and save the results. This will give you a set of aligned frames that you can make your timelapse animation from.