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Basics of Time-lapse Photography
After seeing some of the beautiful time-lapse movies of the night sky by Bernd Pröschold, I decided to try myself. Thankfully, Bernd published an article in Interstellarum titled "Bewegter Himmel" ("sky in motion") where he gave many valuable tips and described in detail how he did it with his DSLR.
- Tripod + Ballhead
- External power supply
- Lens heating
- Timer remote controller
- Memory card
There is one major problem if you want to record a time-lapse movie over night in a remote location: power supply. As exposure times are long at night (my default value is 25 second exposures at 30 second intervals) the shutter is almost constantly open for hours! So your camera's battery won't last long. Even a battery grip does not help much. And, you may not be near your camera all nicht long to change batteries.
Bernd used some heavy lead-acid-batteries (or similar haeavy types) to power his DSLR via external power cord. These batteries give you 10 Ah or more, but, weigh several kilograms. Too heavy if you want to take your equipment on a hike. I found a leight-weight alternative which seems to be quite a recent development: A lithium-polymer-battery. It is not cheap, but, gives you 10 Ah at 12 V and weighs only 860 grams. Mine is manufactured by Austrian Hellpower Industries and can be obtained via M3Shop.com.
This battery enables me to do at least two 17 hour runs without recharging, so 34 hours altogether.
Preventing Dew Formation
In damp locations it usually is a big problem to prevent dew from forming on your lens over night. As power supply is already limited in a remote location using electric heating via resistors is out of the question. Bernd recommends using fuel powered pocket warmers (mine are from Peacock). These are totally safe if handled properly and provide heat for up to 12 hours.
Attaching these (e.g. two) to the lens is a bit problematic and you probably need to make a proper mounting. I have not yet found the best solution in my opinion. Currently I use aluminium foil. It is very light-weight and easy to carry. I wrap it around the lens including the warmers. This nicely insulates the lens from the surrounding air and keeps it warm (above the ambient dew point). This assembly really passed the test in a foggy night in Tasmania when camera and tripod were totally wet the next morning (probably need to cover the camera somehow next time!). The lens, however, was dry.
Timer remote controller
To take photos at certain intervals, you will likely need a timer remote controller for your camera. I use Canon's TC-80N3 for my 40D.