Time-Lapse Photography
by Dennis Allen

I've been doing time-lapse for a couple years. You can see my current collection by clicking here. If you want to duplicate my attempts at time-lapse, first get a digital camera with a 12-50mm lens and set it on a tripod. Set the camera on manual, ISO1600 or better, shutter speed bulb (infinite). Camera lens set to manual and focused to infinity. Start off with large JPEG images. Somewhere in your cameraís menus is a dark frame subtraction mode. In other words, after a 30 second JPEG exposure the camera will take a 30 second dark frame. This dark frame is CCD noise and is automatically subtracted from the JPEG image. On my Canon Rebel XSi 450D it is called "Long Exposure Noise Reduction", found in the custom function settings. Turn it on.

Youíll need an intervalometer. That's an external trigger mechanism thatíll take continuous 30 second long shots. On amazon.com I found "Timer Remote Control RS-60E3 For Canon XS XSi T1i XT XTi" for $16.95. Does the same job as an expensive $150 unit. The intervalometer should have three modes: Duration. For my unit, it's set to 30 seconds. Delay. For my unit, it's set to 62 seconds. That's 30 seconds for an image, 30 seconds for the dark frame, and a couple seconds for any shutter bounce (note that some intervalometers don't need duration time added to delay time). Number of Images. Set it to infinite. The number of images will depend on how long you run the camera. With the display screen off, I can get about four hours on one regular battery.

To avoid dew, I'll hit the camera once an hour with a hair dryer between shots. If I know it's a dewy night, I'll wrap the lens with an Orion dew zapper set on low.

After a night worth of images, upload the camera JPEG images to a new folder on your computer. Check your images. If they're too dark, might have to adjust the images to bring out detail. I like to use PhotoShop Elements. Try "auto level" or "auto color" to bring out the Milky-Way. The latest PhotoShop Elements has a batch mode, so once I figure out how to adjust one image the batch mode can duplicate that adjustment for all images. Oh, make sure to save your JPEG images at their highest resolution.

I've been using a copy of QuickTime Pro. From the registered QuickTime Pro, select File->Open Image Sequence, browse to the new folder, select the first image in it, and specify the numbers of frames per second. I like 12 frames per second, but 24 frames a second is pretty standard. Once the images are loaded, youíll have a new window. From there, you can select File->Export. Under Export, Movie to MP4, select the Options button. Set the file format MP4, not MP4 (ISMA). Set the video format to MPEG-4 Improved. Set the data rate to 1024 Kbytes/sec.  Set the image size to custom, 1280x720HD, preserve aspect ratio using fit within size. Set the frame rate to current, the key frames to 12 frames.

Is anyone familiar with these options? My videos are still coming out a little grainy. My 450D camera produces 4272x2848 images, but if I try to save the video at that size I'll get a 12Mb file. I need to figure out is how to reduce the file size, yet avoid the grainy images.

Anyway, that should get you started. Once you're comfortable with the process, you might want to try different techniques to get better results. You could, for example, double the number of shots by simply disabling dark frame subtraction. Instead, create a single dark frame image by taking a single 30 second shot with the lens cap on. Then you can manually subtract this dark frame image from all the other images.

Note: You might want to create a library of dark frame shots for your camera. That is, a set of dark frame images taken with different time lengths and at different temperatures. For example, is you ran a set 30 second images last night and it got down to freezing, you'll need a 30 second/32 degree dark frame.

The next thing to try is shorter exposures with a higher ISO. A 15 second exposure at ISO6400, for example, might be the equivalent to a 30 second ISO1600 shot. A 15 second shot is so short, you wouldn't be a need to subtract a dark frame from it. Which means more than doubling the number of exposures in a given session.

You could try taking RAW images. I understand the software that comes with the new Canon cameras is pretty good. And you'll need to play with RAW images if you want to learn to stack images later on.

You might also want to play with Photoshop Elements. Instead of "auto level", manually adjust levels. I tried to slid the levels scale over from 0, 1.00, 255 to 0. 1.0, 100. Seems to get better images, but I haven't figured out how to do it in batch mode.

I understand it, Apple discontinued QuickTime for Windows. Microsoft discontinued Windows Movie Maker and Adobe discontinued PhotoShop cafe. Well, Adobe Premiere Elements does time-lapse (you can upgrade Elements to Premiere Elements for $120). I also figured out my copy of Nero Video can do time-lapse. In Nero Video, create an express movie. Standard 4:3 screen size. Load the video with your set of images. Highlight your set of images, click duration and set it to 00:00:03. This is roughly equivalent to 12 frames per second. Export this video to file, MP4/MP4-3GPP. Note: If you use advance editing you canít go back to express editing and will lose the ability to change duration time.

If anyone else has any suggestions for settings, software, etc., again, let me know. You can see my current collection by clicking here. For other attempts at time-lapse photography, see Randy Halverson's Milky-Way masterpiece or see the work done from the VLT in Chile. When I learn more techniques, I'll update this article.

Note: In a couple of my time-lapses, the star field remains stationary and the earth rotates. For this effect I used Picture Window Pro, composite tool, two point shift/alignment, operation registry. I used the first image as an anchor, shifting all subsequent images on the same two stars.


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