Saturday, 17 June 2017

Time lapse and motion blur (Final Cut)

I have a slight dilemma with my new camera. It can record for about two hours because (a) the 256G card I have records about that and (b) the battery lasts about that long.

So, if I want a time lapse I have to change battery every 2 hours or so anyway, so may as well change memory card. Hence not a lot of point in recording in "time lapse" in the first place unless I can connect some mains power to the camera. There may be cases where that is sensible and the time lapse feature in the camera makes sense.

However, for now, I figured I may as well record in real time, and then make a time lapse in Final Cut Pro. It is very simple to tell it to speed up a clip.

There is a down side, the time it takes to transfer and process 256GB of data at a time, and so on. However, I think Final Cut Pro could do a better job than the simple time lapse.

The first thing that occurred to me is that the time lapse would be good if it did a proper "motion blur" on the images. So if I am doing 60x time lapse, process 60 frames to make a motion blur for each frame.

It turns out that whilst this is not a native feature of Final Cut Pro, it is a feature of the titling functions. So by buying the "Motion" system, and creating a text title with no text in it and set to do motion blur as a feature, I can overlay that on the sped up video. Yes, it is complicate to make it (and you can google for videos of how to do it), but it works.

Down side it that it takes a while, well, especially if you do 60 samples at 60x speed like I am. It takes a very long time! I need a faster machine (roll on December, Apple).

But the result is impressive.

So first the non motion blur video - which is as you might expect - still very good :-



And now the motion blur version :-



As you can see, quite a difference. It makes for a very different time lapse, and looks ghosty - see next post for the fix!

So, when the do eventually start building the actual climbing frame, etc, I should be able to make a nice time lapse.

4 comments:

  1. I've always find time lapses work better with a stills camera than a video camera. It does run your shutter count up quite quickly, but gives you much more control over the end result, and the extra resolution lets you do pans and zooms in post rather than investing in an expensive camera slider.

    For a smooth looking motion blur you want the shutter open long enough to give motion trails but not so long that movements disappear. For people, 0.5-2 seconds is a reasonable ballpark. Indoors a small aperture (which you'll probably want for depth of focus anyway) and a low ISO will probably suffice in getting you to that sort of shutter speed. Outdoors you might need ND filters.

    As an example, This video was shot using a cheap-as-chips Canon Powershot A70 at one frame every 15 seconds with a 0.5 second shutter over a period of about 2.5 hours.

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  2. I actually prefer the original. The effect as applied to the 2nd video is way over the top. Maybe if you dialled it back a touch.

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  3. Hate to disagree, Adrian but I much prefer the standard time lapse.

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    Replies
    1. Agreed. The motion blur video feels a bit "ghosted" to me, hard to see what's going on. I also hate motion blur with sped up videos in general.

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