Crank Up the ISO for Night Shots

For those of you who don't live in New England (or watch TV news) we had a bit of a blizzard here this past weekend. Considering that nothing (at least nothing I know about yet) blew off my house and the snow was powdery and easy to shovel, it was actually kind of a fun storm. The wind howled mercilessly and at times I thought the entire house was going to get lifted off its foundations and dropped in a snowy Oz. It didn't.

It was too cold and windy to go out shooting the day after the storm, but by that night I was really restless to shoot some pictures. I noticed the little spiral tree on my front lawn looked pretty from my office window (on the second floor), so opened the window and tried to get a shot. There was a small bookcase in the way, so I couldn't get a tripod close enough to the window to frame the shot I wanted. There was also a roof overhang in the way, so I actually had to lean out of the window (keep in mind it was about 15 degrees out and the wind was still howling) to get this shot using a 70-300mm Nikkor zoom on my D90 body. But the only light was from the tree and so, without a tripod to steady the camera (the lens has no image stabilization), I had to use the max ISO of 3200. I have rarely had to use that speed before, so it seemed like a good experiment anyway. But even at that top ISO speed, I had to shoot at a shutter speed of 1/60 second (at f/4). And trust me, steadying the camera on a snowy window sill with the wind hitting me at 40 mph was still an adventure. Luckily I don't think any neighbors were watching in the middle of the night.

I think the quality of the shot is pretty good considering the high ISO. I can see noise pretty obviously in the snow at the bottom of the frame, but it's not a distraction. And the colors in the lights themselves are pretty true to their real colors. So, while I would probably not use such a high speed as my first option, when the situation calls for it, it's nice to know I can go there. Of course, some cameras claim a top ISO of 100,000 these days (for shooting what exactly--bats in a cave at midnight?), but 3,200 did a good job here. The next evening I went outside and shot the same tree (from street level) on a tripod at ISO 200 and that shot is posted below--you can tell me if you see much of a quality difference. (It is better, no question--but the question is: by how much?) I'm going back out tonight to shoot it from the street with a longer lens--I'll play some more then!

Raise the ISO Speed in Low Light

Virtually all digital cameras have a flash that provides instant light in situations when the existing or "available" light is very low. Flash is handy, but it's rarely very attractive. The reason is simple: the light from a built-in flash is coming from the same place that you're standing and it provides a flat, often over-powering light that pretty much erases the mood of the ambient lighting.

Fortunately digital cameras provide an alternative to using flash and that is the ability to raise the ISO speed when you encounter dim settings. The ISO setting is merely a rating of a digital sensor's ability to respond to light and the higher the ISO, the more sensitive it becomes to low light. In the film days you had to buy separate rolls of film for different situations: a low ISO film speed for bright daylight and a faster one, such as ISO 800, for darker surroundings. But digital cameras, bless their little microprocessor hearts, have an "adjustable ISO" that lets you change the ISO speed from frame to frame.

In other words, if you were photographing the exterior of a cathedral in bright sun, you could use a relatively low ISO, such as ISO 100 (the typical default speed of many digital cameras). If you then wanted to move indoors, where the light is extremely low and flash is not allowed (or very desirable), you could raise the ISO high enough so that you can shoot at a safe handheld shutter speed. To photograph the candles in Notre Dame in Paris, for example, I raised the ISO to 1600 (the maximum for my Nikon D70s camera) and was able to shoot handheld at 1/60 second without any need for flash. Had I used flash the candle light would have disappeared and I would have gotten a great deal of glare from the votive glasses.

Incidentally, the benefit of using lower ISO speeds when light allows is that the images are free from digital "noise" which is the grainy-looking appearance that higher ISO settings often create.

Many cameras have an automatic exposure mode (usually the green "A" mode) that continuously adjusts the camera's ISO setting as the light intensity changes. Read your manual to see how your camera handles setting different ISO settings. Knowing how to adjust that setting will provide a lot more flexibility in changing lighting conditions. There is a more detailed explanation of ISO speeds on my main site.