Please watch Tutorial 2 (vimeo.com/54344263) for information on how to Batch Process hundreds of images using this technique.
I'd like to invite you to stop by timelapse.org and check out some of the incredible timelapse videos created by people from all around the world. If you have questions about this or other issues related to timelapse, then please do join us in the timelapse.org/forums where there are a lot of great people who will surely be happy to help!
I created this little tutorial as a way to answer a question posed by a member of the timelapse.org/forums on how people are achieving such rich and deep dynamic range on their timelapse sequences. Like a lot of people, I played with shooting bracketed images in sequence to create an HDR timelapse. The challenge with doing it this way arises when you try to shoot a timelapse with a fairly short interval.
There are a couple of reasons for this. First, shooting with a wide angle lens (the preferred lens for many people shooting timelapse) at low ISO usually means a fairly long shutter speed (since wide angles tend to be slower - a high f-stop). Second, RAW files (again, the preferred format for most people shooting timelapse) are much larger than jpgs, so they take a lot longer to write to memory. Fast memory cards can help, but there are also limits to the write speed from the camera itself. Cameras include memory buffers to help with the writing speed problem, but even cameras with large buffers can end up with full buffers if too many photos are shot in too short a time.
With timelapse, we shoot of hundreds or thousands of stills in short succession so watching the camera's buffer is critical. In fact, when setting up a camera for a timelapse shot, you always want to make sure that your buffer clears before you take your next shot (or set of bracketed shots).
So shooting 3 or 5 bracketed RAW shots for an HDR can easily take 6 - 10 seconds (could be more or less depending on the aperture of your lens, camera write speed, and memory speed) from the time you shoot your first image of the bracket to the time the last image shot clears the camera buffer.
If you want to shoot a high dynamic range timelapse with a shorter interval than say 6 seconds, there are really only two options - either shoot bracketed jpgs, or shoot a sequence of single RAW images and create a pseudo 3 image bracket out of each RAW to create pseudo-HDR images that you then combine into your squence.
In my opinion, this pseudo-HDR technique actually creates more realistic looking HDR timelapse sequences than genuine HDR timelapse sequences. When used correctly, HDR for stills can create super deep rich images that convey a lot of power. But turning those same images animated into timelapse almost always look surreal and over-saturated - causing a bit of sensory overload. The pseudo-HDR technique will keep your timelpase within the realm of possible and plausible, and the movement in your shots combined with the deeper dynamic range, will result in some great looking footage.
I've shot both real and pseudo HDRs, and I've found I can achieve the best control and results by shooting non-bracketed RAW and creating pseudo HDRs.