Saturday, March 26, 2011

Night Trees

the burning sky
reddens treebark and branch—
city of nights

restless night walk
with camera and tripod,
passerby exclaims:

"Is that a camera?"
a favorite time for photos

My mood personally apocalyptic. The end of my rope coming on like a derailed train, sparks flying off the rails. Wander out for solace, for distraction, to make night photos as a way of making art, to get out of the house where I've been stewing too long in my own juices—but the sky too is full of the end of the world. Sodium vapor streetlights make the world seem yellow-orange, the clouds reflect red. Older mercury vapor lights made things green and blue. The tree-edges move in the breeze, blurring. My hands deep in my pockets, stiff with cold. Frost on the bridge rails. Thrum of tries against the cold road. Water flowing under cold black and at flood stage. The mind clear, for the moment, of everything not related to making images. The confocal nature of redemption. Circles of light under the streelights, against the traffic's tide. Murderous flash of light, sky streaked with unmarked helicopters eggbeatering by in a hurry. Time to walk home on cold feet, to go in, light the fireplace, try to sleep.

Restless, unable to sleep, a few nights ago I grabbed a camera and tripod and walked the quarter-mile down to the bridge over Turtle Creek. I took several time exposures, working for a long time in B&W, with the winds blurring the tree-edges and clouds on longer exposures. Then I switched to color near the end, using my flashlight and laser to paint the trees and path while making more photos.

This is a kind of night photography work which I first began to do almost 20 years ago. I've become expert enough in its techniques to have taught a class in night photography a few times. A tripod is required, and weights if it's a windy night. Your camera needs to have Manual settings capability, so you can control the exposure time and the aperture. Automatic cameras or settings are incapable of this kind of photography, with their ignorant insistence on using flash and short exposures: you'll get a lot of empty black frames.

The aperture, of f-stop, is the setting for how open the lens is to let light in: the higher the f-stop number, the smaller the opening, or aperture, and the smaller amount of light that gets in. This also controls, however, the sharpness of the image, and the depth of field. The smaller the aperture, the greater the depth of field; with a very small aperture, virtually everything in foreground, middle- and background will be in sharp focus.

Exposure times are inversely proportional to aperture size: If you have your camera stopped down to a high f-stop, or smaller aperture—effectively letting in less light—you will need a longer exposure time. As a general rule of thumb, the exposure time usually doubles for every f-stop you click down.

I almost always prefer to do night photography on an ASA rating, or film speed, of 100 ASA. This keeps the film (or in this case, digital CCD) from getting too grainy. Higher film speeds allow you to capture more light faster, being by definition more sensitive to light; but they also get grainer, or in the case of digital cameras, noisier. Most digital cameras will allow you to shoot up to ASA 1600, but you'll see a lot of pixel noise in your image. So to get a smooth image without grain or noise, you need to use the lowest ASA speed you can, even though that will mean very long exposures at night under some conditions.

For example, in astrophotography, or photography of the night sky, such as the Milky Way, exposures longer than an hour are not uncommon. I have experience working with exposures up to about 30 minutes long. For night photography, with the f-stop set at f32, it's not uncommon for you to have to do a two-minute exposure at ASA 100.

It was cold out at night. I bundled up in my heavy fleece coat, and still got chilled by standing next to the tripod while the camera counted through 4- and 8-second exposures. It was cold enough that the camera started to flash its low-battery alert warning; batteries, when they're too cold, lose power, suddenly dropping to zero. Once or twice I took the camera off the tripod to warm it against my chest, under my jacket, before remounting it and continuing to make photos. A common winter problem when outdoors making photos.

This was an 8-second exposure, with the foreground tree splashed with the light emitted from my handheld flashlight laser. That's what makes the red streaks on the branches.

With longer exposure, a handheld flashlight, or flashgun, or a laser, as here, can be used to illuminate part of a composition, for special effect.

This is two separate exposures layered in Photoshop. One of them used a handheld flashlight to splash light on the tops of the trees in the background, while the other exposure used the laser to splash lines on the foreground tree.

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Anonymous Danny said...

I used to love doing this kind of photography! It's been a while.

11:20 PM  

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