One of digital photography’s largest advantages over film is the ability to change ISO settings on the fly. For those new to the game and not familiar with the idea, a roll of film was set to the same ISO and once loaded, typically was not removed until all 24 or 36 shots were done (or 10 or 20 shots for most medium format backs). This meant if 100 speed film was in the camera and you went inside to shoot in low light, it was hard to get decent results.
With the advent of digital sensors, the ISO setting, which represents the sensor’s sensitivity to light, became adjustable image by image. It was a boon for those of us who might hit a lot of different lighting scenes in the course of a day. Bright light, low light…it didn’t matter. Just take a second to adjust the ISO before shooting and presto! No worries about blur!
Take that one step further and it seemed like utopia had been discovered when Auto ISO was unveiled. It was something of a holy grail; now here is the chance to forget about ISO settings and concentrate on the scene at hand.
But hold on before you get too excited. Auto ISO has its limits. The main detracting factor for Auto ISO is the camera’s propensity to use it without consideration for the consequences. You see, your camera doesn’t care about noise in images, but your image viewers probably do. And if you care about your art, chances are you don’t like noise in your shots either.
And for a while this was the way it was. A camera might have an ability to obtain an ISO 3200 setting but do you really want to use it often? For those of us who answered, “No” we were stuck with setting our ISO and making it one more consideration before shooting. Until the manufacturers picked up on the feedback from the field.
I’m not sure who introduced the ability to limit Auto ISO first, but I’m inclined to tip my hat to Nikon as most of their cameras have the ability, with other manufacturers finally catching on. Who was first really doesn’t matter, because now that most manufacturers are adding in the ability to limit Auto ISO to future generations of cameras, we all win. I have come across enough students in my teachings that did not know this feature even existed that I hope more people will benefit from this post and start improving their photos by not letting ISO get too high.
Noise from camera sensors typically starts making itself known around ISO 400 or ISO 800. It’s different for different cameras depending on sensor size and manufacture. For those unfamiliar, noise is not grain, as in the days of film. Grain can be appealing, but noise is almost always considered ugly. It looks like the image below and typically shows up in darker areas. The first image is ISO 100 while the second is at an extreme of ISO 12,800. Click on each image for a larger zoom.
This is why it is important, if you use Auto ISO, to limit the setting. Nikon and Canon menu listings can be seen in this post and it’s beyond the scope of this post to point to every camera model’s exact location. Refer to your owner’s manual for more information on how to set the Auto ISO maximum.
Curious about what to set for your maximum Auto ISO? This is a subjective matter and will depend on your likes and dislikes. Take some sample images at different ISO settings in different lighting situations. My typical suggestion is nothing higher than ISO 400 for Auto ISO. If you want a higher ISO because the situation calls for it, then make the conscience choice to raise it.