Wednesday, September 06, 2006

Night Photography

Night photography can mean long exposure tripod shots, hand held flash photography, or available light photography. Since I do not own a flash (speedlite) I will discuss available light and tripod type situations.

Available light (No tripod):

For low light conditions where you must use ISO 800 and up I tend to
  • Shoot in RAW format- in fact I always use RAW format. It just gives you more options later as far as white balance and exposure are concerned.
  • I sometimes process noisy RAW files using DPP (canon's software) instead of Camera RAW . Sometimes there is a world of difference in the quality. The output(saving to 16bit uncompressed tiff) of DPP seemed significantly less noisy then the output of Camera RAW. (IMHO, others may disagree)
  • Shoot manual (M)- Use a fast lens like a 50mm f1.4 or f1.8. Also, I find the 20D's ( I shoot with a 20D but it is mostly still true for the 350D) light metering is too conservative with a 50mm f1.4 . I will take a couple test shots and adjust shutter/aperture until the histogram looks "acceptable".
  • Use the middle focus point only. (the lens with "hunt" less)
  • Converting to B&W can improve the look of a photo since it removes colour noise. Also converting through the red channel can help with complexions. (You have to balance this with a loss of detail)

What can you take photos of at night anyway? Well everything you photograph during the day of course expect maybe the sun. Also with the lack of light during the evening it is easy to play with slow shutter effects like panning

Street motion

Long exposures (You have a tripod):

I shoot most of my night photography around the full moon. Since we are now using a tripod a fast lens is not so important. I enjoy using a wide lenses at night like the 17-40 f/4 but sometimes fall back on the 50 f/1.4 depending on the available light. However, when the moon is in the frame I have found the 17-40 f/4 has less lens flare then the 50 f/1.4.

A solid tripod is a must for long exposures. I shoot in RAW format, auto white balance, ISO 100 and use manual for everything else. The lower the ISO the less noise you will have. The best nights are when the moon is (close to) full. With a full moon and a wide lens you can stop your lens down to f/10 ish for a more or less infinite DOF. For example at 17mm f/10 the hyperfocal distance is about 2.6 meters. So setting the focus to 2.6 m means everything from 1.3 meters to infinity is in focus. Although this can be difficult to achieve in practice with the scale on your lens. Another trick (I have heard) is to shine a laser pointer on the object and adjust your focus until the dot looks the sharpest. You could also bring a flashlight.

The exposure time depends on where you are. If there is little ambient light then I usually start with a 5-6 min exposure and then adjust accordingly. In the city you can get backlighting and ambient lighting issues. However, they can sometimes provide interesting shadows like the trees did in this photo.

Martello Tower

I have not used canon's in camera noise reduction function. My longest exposures to date are about 14 mins. To get exposures longer then 30 sec use the bulb setting on your camera and it helps to use a remote to prevent camera shake. This shot is about 14 mins and since there was no moon I had the lens wide open at f/4.

Star spiral

In the above photo the star trails are of course caused by the rotation of the earth. A rough estimate at exposure time when star trail will become noticable in the photo is 600/(focal length) seconds.

One more thing that adds to nightshots is moving clouds. Over a long exposure their streaks provide texture to the sky like in this photo:

Against the flow

Now get out there and take some photos...


Blogger martin said...

I already take lots of those, but reading all these writeups has made me think about writing up what I do. There are a lot of similarities, but also a lot of differences, especially in the workflow. :)

10:36 AM  

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