Friday, August 22, 2014

HDR Time-lapse Workflow for Canon 60D

Making an HDR (High Dynamic Range) time-lapse movie involves a series of procedures that require planning, a little math, camera settings and post processing. In some shooting situations, you could be in rush and might forget one or two key steps that end up realizing a less ideal production after the session. During the workflow, especially in the shooting sesison, I would always go through my checklist if possible to make sure those key steps are followed and properly setup. I would like to share such a checklist I have developed for my camera Canon 6D. This should be applicable to most of Canon EOS series models.
The workflow: Planning → Camera settings → Intervalometer settings → Shooting session → HDR tome mapping → Time-lapse movie making.





Planning

Depending on different scenes, the properly selected interval between each shot determines how the frames will flow in your final movie. Here is a table of typical intervals for popular time-lapse scenes.
Typical ScenesRecommended Interval
Fast moving clouds
Moving traffic
Drivelapse (shooting while driving)
1 second
Sunset / Sunrise
Moon near horizon
Slow moving clouds
Crowds
1-3 seconds
Moving shadows
Sun or moon acrossing the sky (wide angel without clouds)  
15-30 seconds
Stars or star traces15-60 seconds or more
Fast blossom flwoers
Fast growing plants
90-120 seconds
Construction site5-15 minutes

Camera (Canon 60D)

  1. set the camera on a solid tripod
  2. turn OS off
  3. connect a intervalometer to the camera
  4. focus on your subject with AF, then turn AF off; or just use manual focus
  5. set to manual (M) mode
  6. set shoot mode to High-speed multiple
  7. set image quality to Fine (jpeg only, no RAW if you experience slow buffering )
  8. select image aspect to avoid crop in post-process (16:9 for video)
  9. set WB to a manual mode according to the shooting condition (Daylight, Shade, etc.)
  10. set ISO based on lighting and noice tolerance
  11. set aperture based on the required DOF (see note below for avoiding flickering)
  12. set shutter speed based on the required proper exposure
  13. take a test shot, and check the exposure histogram and depth of field
  14. if for HDR, set bracket (ABE) to +/- 1Ev, 2Ev or 3Ev depending on scene, adjust the under/over exposure scale
  15. take another test HDR shot  (see Intervalometer setting for one shot), and check the histograms of the 3 shots
  16. create a new folder for this time-lapse session
  17. Other optional settings
    • turn Beep off
    • turn Image Review off. And also cover the LED screen off.
    • turn Auto Lighting Optimizer off

  18. Note: Tips to avoiding flickering
    • keep the same exposure for each shot, 
    • shorten interval between shots whenever possible,
    • keep f/8 or wider when possible. Smaller aperture (< f/8 or further) may cause shutter not going back to the exactly same position for each next shot, thus causing artificial flickering.
    Note: For convenience, configure teh above settings into a customized dial C1 or C2. So for next shooting session (if similar conditions), just simply turn the dial to C1 or C2, then just start shooting.

Intervalometer


  1. Delay (in seconds): A delay to release shutter of the first shot. Normally set to 0.
  2. Long (in seconds): 
    • in regular mode (M), it is the time enough to cover 1 shot. Set it to equal to or a liitle longer than the shutter exposures time;
    • in HDR mode (M), it is the time enough to fire all 3 shots. Set it to equal to or a little longer than the sum of shutter exposures of the 3 shots;
    • in Bulb mode (B), it is the time to hold the shutter open. 
  3. Interval (in seconds): it is the time between two shutter releases. (Note, for HDR, one release has 3 shots). An Interval should be typically set at least longer than a Long plus some processing time for camera to clean the buffering.
  4. N: the number of shutter releases. Considering each will consume at least Intervalseconds when you calculate the total time for completing the shooting session.

Shooting Session

Now, you are ready to fire the shooting session. During the session, when in a windy day, try to hang more weight to the tripod for stability.

HDR Tone Mapping

There are certain HDR software for tone mapping the bracketing shots (one normal exposed, one under exposed and one over exposed with +/-xEV). I recommend HDRSoft's Photomatix Pro.
For example, if you have 3000 HDR shots in your session, use the middle set of 3 as the benchmark to develop the tone mapping first with Photomatic Pro. With fine tuning and adjustment, you save this as the template for all your 300 shots in a batch processing in Photomatix Pro, this will take quite a long time. I typically run it overnight with my iMac. Name a specific directory for your tone mapping output. After the process finishes, you will have 1000 tone-mapped images in sequence and ready for your time-lapse movie.

Time-Lapse Movie Making

As a Mac fan, I always use Quicktime Pro to make the time-lapse movie. After invoking the Quicktime Pro 7, go to File | Open Image Sequence..., in the Open window, browse to your tone-mapped image directory and just select the first image of the sequence. Quicktime Pro 7 will ask you to specify frame rate (I typically choose 24 fps). Then all images in the sequence are loaded. With resizing for the movie (1920x1080, or the size for your targetted playback device), you then save the movie by selecting File | Export..., with video quality settings at your choice, then save to a movie in your chosen format (Quicktime .MOV, H264 .mp4, or others encoders). 

With more practice, I hope you will have developed a better workflow for your specific needs. If you like to see some HDR time-lapse movies I have made, see them in my gallery.



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