Wednesday, October 16, 2013

Seeing In The Dark

How well your camera is able to see in the dark may be of interest to you if you do a lot of night shooting, or plan to. It can be a tall order, demanding high ISO values, low noise, a lens that shoots well wide open, and shutter speeds that can be hand-held, unless you've always got a tri-pod with you. In this case, I would favour digital SLR's, because film simply can't reach the high ISO values needed, especially for colour - a tri-pod is essential. A lot of DSLR's can fall down on the job at night too, especially when you need to under-expose the shot... there are two reasons to under-expose at night... 1) to make it look like night, because modern DSLR's can reach such incredibly high ISO's they can literally turn night into day, and 2) under-exposing can help you reach shutter speeds that can be hand-held. Conventional wisdom for shooting a digital camera in daylight is to "expose to the right" (over-expose) slightly, to avoid adding noise during post-processing. It works this way because most of the 'data" in your RAW file is held in the brighter values, and so the brighter you can shoot, without blowing out highlights, the more plentiful, and cleaner is the data you have to work with.

All of these night shots were taken with my EOS 5D Mk-1 with Canon's low cost EF 40mm f2.8 (the Pancake) lens, wide open at f2.8, with the camera set at ISO 3200, which is as high as it will go, and under-exposed by two stops.






In post-processing, I dialled up the exposure a bit, to recover shadow detail, and enhanced the Local Contrast in both the shadows and highlights, but not the mid-tones. This raised some noise, for which I applied a touch of noise reduction, because I didn't want to remove all the noise - just enough to remove the digital looking "speckle", but also to keep the noise that looks like film grain. It is surprising how much detail is available in a RAW file that can be raised back up above the noise floor, so to speak. In fact, I might have gone a little too far in raising the brightness here, as these pictures are much brighter than what my eye was actually seeing.

This time of year in the Northern climate lends itself perfectly to night shooting, with the night falling at around 7:00 PM. When you go out to give it a try, remember these steps - 1) shoot RAW if you have it, 2) select the highest ISO possible, 3) open your lens aperture to it's widest value, and 4) adjust your Exposure Compensation or Shutter Speed to get your camera's light meter to show around -1.5 to -2, and verify that your shutter speed is hand-holdable, like 1/20 or better (or minimum 1/5 if you have Image Stabilization).

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