Pixean
Nov 28, 2018

Time-lapse photography involves the stitching together of several images to form a video. It has the ability to depict an entire event in a much shorter duration of time. However, as we all know, the video is not actually sped up. So how is this achieved? Well, time-lapse photography involves certain parameters like time interval and number of shots. The time interval is the interval between two successive shots. For example, if you are shooting a time-lapse with an interval of 10 seconds between each of your shots, you have the ability to depict a minute of action with just 6 shots. This calculates up to 4 minutes of action with 24 shots. When you place these 24 images in a 24 frames per second video sequence, it gives you a 1 second video. Thus you are actually depicting 4 minutes of action in just 1 second! This is what speeds up the video. When you are playing a set of 24 images continuously, all of them need to have the same exposure. Otherwise, slight changes in exposure can actually catch all the negative attention of your viewers. This is what we call the time-lapse flicker. Let us try to understand the concept of time-lapse flicker and the ways to rectify it.

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Image courtesy RE:Vision Effects

Time-lapse flicker: The exposure changes in some images can be easily noticeable in the form of exposure jumps when a set of hundreds of images are played successively at a high speed. This is one of the biggest challenges in time-lapse photography.

Reasons for time-lapse flicker: For example, you are shooting a time lapse video of a sunset. You have your camera in manual mode with a specific set of exposure triangle parameters. During a sunset, changes in lighting are quite common. These changes in lighting conditions will affect the exposure of your images since you kept the same exposure parameters for all the photographs. When you playback these images later, you will find several exposure jumps in the video.

Solutions to the problem: There are a few ways to fix this time-lapse flicker problem.

  1. Exposure settings in your camera: You should always try to get things right in the camera itself. The exposure settings in your camera must be perfect in order to capture a perfect set of images. The mode in which you need to shoot will differ from place to place. There is no single proper mode to shoot time lapses in. In case you are shooting a time lapse indoors, check out for the lighting conditions. If you are using artificial lights for the shoot, then the chances of having changes in lighting conditions are minimal. Here you can use the manual mode to shoot the time lapse. Adjust your exposure settings in the camera and get some test shots. Once the histogram of your shot seems appreciable, you are ready to start the process. Let us consider the same case during an outdoor shoot in partly cloudy conditions. The sun normally appears for a few seconds before being hidden by clouds again. This means there are frequent changes in lighting conditions. If you shoot in manual mode, you cannot change the exposure settings midway through the shoot sequence. Hence the camera will not be able to adapt to the changes in exposure. Therefore, it is advisable to shoot in aperture priority mode. In this case, you only need to set the aperture and the camera will decide the shutter speed. You can also keep the ISO at auto. However if you are keeping the ISO at auto, there are chances that the camera will boost the ISO too much, thereby introducing noise in the images. Keep an upper limit of the ISO value as per the maximum usable ISO of your camera body so that it cannot be boosted beyond this. Keep the aperture at around f/8 while shooting landscapes. The changes in lighting conditions will thus be taken care of, by the camera which will keep adjusting the shutter speed and ISO to achieve consistent exposure. You can also eliminate the flicker by shooting in slow shutter speeds like 1/10th of a second or slower. You may require a neutral density filter for the same.

 

  1. Post processing: Time-lapse flicker can be eliminated in post processing too, thankfully! In case you failed to achieve consistent exposures in the field, post processing can help you get there by simple tweaking of a few exposure sliders. Import the images in Adobe Lightroom or any other post processing tool. Playback the images to locate all the exposure changes. Adjust those by simply adjusting the exposure related sliders like, brightness, highlights and shadows. Sync your settings in all the images you need to and you have already achieved the required consistency. There are several other de-flickering tools too like GBDEFLICKER, TLTOOLS etc. that can handle the flickering efficiently.

 

  1. The hardware way: This may not be advisable for all but this is certainly a technique used by some. The digital cameras these days control the aperture of the lens digitally, and hence there are chances that the size of aperture opening is not exactly perfect every time you shoot an image. You can rotate the lens a little to disconnect it from the electrical contacts of your camera body, after having pressed the depth of field preview button and shoot that way. This will convert your electronic lens into a manual one with the size of aperture opening remaining fixed for all your shots. If the camera fails to detect the lens, you can use tapes to connect the electrical points. However, this is not advisable for all.

 

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Image courtesy granitebaysoftware.com

 

Time lapse photography has its own set of challenges. The flicker is one of the most annoying challenges to counter. With the above tips, you can get your settings right, in the camera itself. If not, there is post processing to help you achieve a certain level of consistency in your time-lapse videos. You can always playback the video and check for exposure jumps and correct wherever necessary.

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