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26th September 2009, 10:02 AM
Time-lapse photography, the finished results...
Click here to skip to the page with the time lapse videos, or carry on reading below for details.
Since its more video than pictures, im putting it in here rather than the gallery.
Those paying attention to the other time lapse thread knocking around here may have noticed my promise a while ago of videos to come, so here they are finally.
The full array of videos is available at the new time-lapse page on my site, but i will just draw attention to a couple to highlight the paticular things that the canon CHDK enabled (all of this was shot with a canon A720 with CHDK).
The first is the biggest. A 12 hour drive from SW France back to Surrey, UK, compressed into 30 minuites (Available on youtube in HD pt 1, pt 2, pt 3.) This was done using a 'fast intervalometer' script which basicly uses the in camera continous shooting function, and electronicly holds down the shutter button to save you finger. This let the camera take pictures at what i figured to be about 4/3fps. The photos it took were at 1600x1200 normal jpg quality, which were emptied from the SD card onto a laptop every two hours when we switched drivers. The camera was dash-mounted with blu-tack and plugged into an AC adaptor from the cigarette lighter. The problem with this script is in order to get the shotting rate so high, it cannot go through the autofocus and auto exposure every time it shoots, so is locked to whatever it is set at first time round. As you can imagine this does cause a few exposure problems when you are going for 2 hours at a time, especially the first set which went from early morening overcast to late morning sunny, resulting in some frames being almost entirely blown. Anyway, the final result was nearly 50000 frames which were loaded into virtualdub and cropped to a 16:9 ratio (1600x900 px) then saved to avi at 30fps@15Mbps.
Second is more run-of-the-mill time lapse, the sunrise into stormy clouds that clear ( HD via embedded youtube on my site.) This is shot using an 'ultra intervalometer' scipt, which lets you set the interval and number of shots. This script also goes through the auto-focus/exposure with each shot, with the focus locked to prevent hunting, this means you can leave the camera in Av, P or Auto modes and it will automaticly adjust the exposure to keep track of the changing light in sunset/sunrise, or just from changing weather conditions, allowing good exposure from the start of this sunrise, into the overcast morning, and right into the sunny bit later with the sun in frame. Again in virtualdub 1600x1200@30fps@10Mbps.
Finally, a timelapse of the stars moving across the sky which uses the previous script, but also uses another CHDK function, which allows override of shutter (and apperture etc) speed, letting the camera take full 1-minute exposures rather than the ~16 seconds it was limited to otherwise, and capturing 4x more light in the night sky (especially out there where there was literally no light pollution to light it up) is a big help. virtualdub 1600x1200@10fps (or 15 fps, cant remember) upscaled with temporal smoothing to 30fps@9Mbps.
This last technique is also great for getting multiple shots of the sky to stack the exposures either unaligned for greater star trails, or aligned in something like auto-pano pro to allow for an exposure stacked image:
9x1Minuite exposures, aligned in Auto pano pro, linear dodge (add) layer belending in photoshop, plus a little play with levels
As an afterword- a big big thanks to all the guys at CHDK who made this possible, and if ive missed out some vital detail, just ask away
Last edited by wjh31; 26th September 2009 at 11:07 PM.