First published May 22nd 2015.
I've always read about the advantages of SMS and the advantages of continuous motion but I've never really had a chance to test it out. So, I decided to take my Kessler Crane Second Shooter out into the garden and have a test - shooting the same shot with the same camera settings and 3-axis move, but changing the movement mode.
Preston Kanak of Cinescapes Collective has written about this in his excellent post on How to Shoot Motion Controlled Time-lapses - if you've not checked out Preston's timelapse tips then you really do need to, they're really awesome - and he's outlined the logic behind using continuous motion. It basically comes down to this:
If you want to avoid motion blur, it is key to keep the distance the camera travels between photos to be minimal.
With this shot, I took 480 photos for both SMS and continuous, and it was basically done back-to-back. I was using a Canon EF 24-105mm f4 L-series lens at 24mm on a Canon 60D, so there's a 1.6x crop factor to be applied to that. It was shot using a Kessler Crane ShuttlePod Mini - 3ft of track and the camera moved down most of it - and the Second Shooter's pan-axis moved perhaps 30º left, tilt-axis was perhaps about 130º of movement... I'm just estimating these figures but this all comes down to what Preston has said - if I had a longer track or there was more pan/tilt movement then with the same amount of photos taken, both the SMS shot and the continuous shot would look jerky and generally quite bad.
You need to take enough photos or have the move be long enough that the movement is minimal. The less movement you have, the better both a SMS and a continuous shot will look.
What do you prefer? SMS or continuous? I'm drifting towards continuous here because I think that it looks better with this sort of move, but is there really a discernible difference with this type of shot? Let me know in the comments below!