Friday, 6 January 2012

Infra-red Stop Motion Fun

Like others I hold on to my old, 'replaced' DSLRs simply through a sense of attachment. Unfortunately if you don't sell gear as soon as it is replaced, it becomes redundant, its second-hand value drops off the map. However, one cool way to revitalise your old camera, point-and-shoot or DSLR, is to have it converted to record infra-red images.

Infra-red photography was popular with landscape photographers back in the 80s when IR film, and processing, was readily available. The IR effect is to render all living plant material in incredible white tones, to make blue skies almost black, and to add a surreal, ethereal feel to any scene. To achieve this on film we had to use a near-black red filter over the lens, make the necessary exposure adjustment, re-focus the lens and then pay for specialist IR processing and printing to get the true glowing white effect. Because it was a bit of a pain only dedicated photographers pursued the process.

Unprocessed infra-red file
Processed black-and-white file
 Using a digital camera to shoot IR is far easier:
- No external filtration needed
- Fast exposures
- Instant results
- The same amount of post-processing that you'd add to a non-IR shot
- Spectacular results

There are several specialist companies that provide a conversion service (I had mine done in the US by The conversion entails the removal of the camera's existing protective filter (over the camera sensor). This is replaced with a specialist IR filter. These are available in different strengths, depending on your personal picture making requirements (see breakout box). All IR filters will produce radical visual results. The main difference between the 'depths' of each filter effect is most appreciated at the post-processing edit stage. Some of the deeper IR filters produce better tonal separation between blue and green tones which in turn make selecting skies, for example, faster. This in turn enables a photographer to produce a more dramatic visual effect. Again, sites such as have tremendous comparison examples for each IR filter available.

Creating IR Stop Motion Video
Another fun and creative use for the infra-red images is to create stop motion IR stills. I suppose this is like a poor man's video in that you shoot individual video frames and then assemble the collective images into a video presentation using video editing software. Sometimes the visual effects created are stunning from something that's relatively simple to create.
IR Stop Motion: Tools needed
IR converted camera + suitably calibrated lens
Remote shutter release cable (optional)
Photoshop or Photoshop Elements
Video editing application (Adobe Premiere Pro or Premiere Elements)

Step 01: Find a good location for your scene. Pick a subject that has both moving and static components in it to best profile the stop motion effect.
Step 02: Use a tripod. As you'll be shooting several hundred frames it's vital not to have any camera/tripod movement.
Step 03: Set the camera to shoot low resolution files. A standard 720p video frame is only be around 2Mb - there's no point in shooting 18Mp frames as this slows the camera and fills the card prematurely. JPEG is best.
Step 04: Set the focus to one specific point in the scene. You CAN change focus manually during a shootinge but care must be taken not to shift the tripod.
Step 05: Set the metering to Manual, make a test shot to get an accurate exposure before starting a sequence. Exposure consistency is important. The faster you shoot (i.e. the more frames) the smoother the stop motion effect.
Step 06: Attach the shutter release cable and start shooting. I usually try to shoot one fps, or faster, but this depends on the subject and the light. If the resolution is too high, or the drive too fast, change the settings. Having a 'fast' card (i.e. a SanDisk Ultra IV) helps, as does shooting in a low resolution mode. 
Step 07: Download the entire sequence. If you have shot several sequences it's good policy to separate each into folders. Next step is to crop each frame to fit the format being produced. If you don't the resulting video might come out with black lines top and bottom or left and right of the frame. Which doesn't look so good. This is normally the HD format (i.e. 16:9 ratio). If you have Photoshop it's easy enough to write an Action to crop and save each image. Processing several hundred frames takes little time. If you don't use PS then you might have to crop each image manually (tedious) or just forget it and go with the format that fits the camera frame proportions (i.e. 4:3).
Step 08: Once the cropping is finished, import into your video software. I prefer to use Adobe Premiere Pro. When importing stills it automatically stretches one image over 25 frames. So one second of video. This is too slow. In the program preferences you can easily reset this so that a still image takes only two frames, thus giving you effectively 12fps. This produces acceptable stop motion.
Step 09: To make editing multiple sequences easier Premiere Pro also enables users to select all the frames in one sequence and Nest them - effectively grouping them as if the sequence was one file. This makes it easier to shift an entire sequence (which might consist of several hundred frames) on the Timeline.
Step 10: To finish, Nest or Group the entire production than add any post-production tone enhancements to the sequence you think necessary. I like adding a Tilt/Shift effect that moves the focus plane to create a miniature 'look' to the production.
Render the entire production and export to your favourite format. Typically this might be 1080p or 720p. Have fun!
TIP: Shoot a blank frame at the end of each sequence to make it easier to identify start and stop points once on the hard drive.

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