The Ins and Outs of ISO Speeds

Posted on 12 December 2011 by MatthewBamberg
In the old film days it used to be that before a shoot, you’d decide what kind of film to use: that is, choose the film’s sensitivity to light. While in those days the choices were ISO 100, 200, 400 and 800, today’s digital cameras have a wider choice in ISO settings with many cameras capable of taking images at ISO 6400 and beyond.

In terms of values, ISO speeds of 100 is considered slow. At ISO 200 the sensor is twice as sensitive, which means that the shutter can open and close faster, giving you less blur from camera shake.

When possible it’s best to shoot at the lowest ISO speed. You’ll obtain brighter, bolder colors and an image that is sharp without any noticeable noise at 100 percent resolution on the computer screen. Images are required to be noise-free and sharp at that resolution in the stock/microstock photography business.
When you use a tripod, go with the lowest ISO speed at which your camera can be set (usually ISO 100). If light conditions are poor shoot at a higher ISO.

If a surface of an object(s) is lit by sunlight, I shoot at ISO 100. On cloudy days and in shady spots, I shoot at ISO 200-400 and at the break of dawn, the last of dusk and anywhere indoors, I shoot at ISO 800.

Mandalay puppet show shot at ISO 1600.

Image by Matthew Bamberg

Setting any digital camera to a film speed greater than ISO 800 or shooting with film that’s over 400 ISO and scanning the prints or negatives/positives sometimes results in noise (referred to as pixilation in the digital world).
When I was in Mandalay, Myanmar, I went to the main attraction, the Mandalay Puppet Show. The theater is dark but there is enough light on the stage to get a decent image for the web, but not for print.

At 100 percent resolution, images shot at high ISO speeds can be soft and noisy.

Image by Matthew Bamberg

The image was shot at ISO 1600 with a Digital Rebel. At 100 percent resolution there is noise and some softness, which disqualifies the photo for any large magazine spread or for stock/microstock purposes.
Images
On the other hand, an image of a modern house I shot at 100 ISO is free of noise and remained sharp at 100 percent resolution. This is because I used a tripod.

Image at 100 percent resolution shot with a tripod.

Image by Matthew Bamberg

Another thing to keep in mind regarding ISO speed is the size of the camera’s sensor. The small sensors of most point-and-shoot cameras are more susceptible to noise at high ISO speeds because the pixels are smaller and can’t receive as much light as those that are bigger, like in the mirroless cameras and the dSLRs.

Finally, you can consider the make of the camera. For example, even though the Canon 5D Mark II has a 21 MP sensor, the images it takes at high ISO speeds are inferior to those taken with the 12 MP Nikon D 700 I’ve found that images taken above ISO 800 For the most part, Nikon has more advanced sensor sensitivity technology than Canon has.
Cameras are constantly being upgraded to shoot at high ISO speeds, but no matter how good they get, they’ll never beat the sharpness and clarity of a photo that is shot with a tripod.

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