Your Camera’s ISO Settings

Your Camera’s ISO Settings

by William Lulow

I wrote this article back in 2013 and I finally decided to publish an update of it. Your camera’s ISO settings are really the starting point for any digital image you make these days. This number actually determines HOW SENSITIVE YOUR CAMERA’S CCD (SENSOR) WILL BE TO THE LIGHT THAT HITS IT DURING AN EXPOSURE!

Most people know these days that the sensitivity of your camera’s CCD is now measured in numbers decided by the International Standards Organization. In the days of film, the sensitivity to light of a film’s emulsion was decided by the American Standards Association (ASA), hence the ASA rating. You will remember that a “fast” film was rated at around 400ASA and a slow film, like Kodachrome was rated at 25ASA. You could “push” a film’s sensitivity by boosting its ASA. But you would pay for it with extra graininess caused by the underexposure and overdevelopment.

In the digital age, CCDs are much more sensitive to light than film emulsions ever were. Now, ISO ratings of 25,000 are not uncommon. The good news is that higher ISO ratings do not have to be accompanied by grainier images. It is true that high ISOs do result in some extra “noise” in the images, but in many cases, that extra noise is tolerable depending on how the photographs will be used. One has to realize that by setting the ISO rating higher, you are still underexposing the image and you may have to alter it somewhat “after capture.” Occasionally, I have had to increase the contrast on these types of images. You also need to keep in mind the end use of your images. Most images are used on websites or posts these days, so you have some leeway in terms of how much enlargement they will use.

So, keeping all these things in mind, you are able to alter an image’s exposure by adjusting the ISO setting, the aperture or the shutter speed.

Here are a couple of images captured with an ISO setting of 2000 – 2500:

This image of famed guitarist Peter Calo (worked extensively with Carly Simon) was made in a very dimly lit nightclub. For all intents and purposes, the “noise” or “grain” of this shot is acceptable for most uses of photographs like this. They probably won’t be blown up to billboard size and will, most likely, be used on a website of some sort. So, for the purpose this shot was intended, not only is it acceptable, but it is really pretty sharp. Look at the clarity of the microphone and the wrinkles on his face. Here is another example:

This is a shot made in another nightclub, with a bit more light. The subject is the well-known singer/songwriter, Paula Cole. Exposure was ISO 2000, f/7.1 @1/125th of a second. Notice the clarity of her teeth, hair and the bracelet on her arm. Everything is pretty sharp without a lot of noticeable grain. This image could probably be blown up to around 30×40″ without suffering very much loss of quality. I have to add that these images were made with the camera mounted on a monopod to help minimize camera movement.

Recently, I wanted to do some images of my granddaughter’s 4th birthday party. I knew I would be making 8×10″ prints at the most, so I decided to photograph the event using fairly high ISO numbers and no extra lights beyond the available. This day, I was shooting mostly at ISO 1000. Here are a couple of results:

The kids were in a gym, running around and climbing on all the equipment. I couldn’t really set up any lights and, as mentioned, I didn’t want to use much flash. So, I decided to just push the ISO setting to where I could get some acceptable images.

The most clear images are obtained with ISO settings around 100 or so. That’s what I use in the studio with my normal studio lighting equipment, and it’s the setting I use most for my scenic photographs. Obviously, the lower the ISO number, the clearer your image will be. But, as with everything in the art and science of making images, you have to decide what is most important in producing the images you want. Sometimes, the ISO sensitivity can be pushed to a certain point where the image quality won’t suffer that much. You have to remember always, that when using high ISO numbers, you are really UNDEREXPOSING your images and the price you pay is that the images are not always tack sharp. But, they may be sharp enough for the intended use.

If you leave your digital camera on FULL AUTO mode, it will pick an ISO for you depending on the lighting conditions. It will also adjust your aperture and shutter speed as well. I always recommend taking your camera off of the automatic setting and to experiment with higher ISO settings on MANUAL mode. This way, you can see more clearly how changing ISO settings affects the image. You can almost tell just by looking at these images, that the ISO was higher than normal. They have a kind of “rough” look to them. By this I mean that the differences between the highlights and shadows are more defined and less smooth. Here is another example:

In this image, everything looks sharp, features are all visible with good detail, but it is still a bit “rough-looking.” There is good background blur because I made many of these images with my 85mm f/1.8 lens. On my crop sensor camera it was acting more like a 135mm lens. For me, the detail and quality here would not be acceptable for a studio shot, but it served the purpose for making the kinds of images I was making that day.

I always teach that photographers really have to make a number of decisions whenever they undertake to shoot a subject with purpose, that is, with an idea in mind of what kinds of images are wanted, needed and are acceptable. Without the necessary thought involved, these would just be snapshots you could obtain with an iPhone or any point-and-shoot camera. In this instance, however, the medium telephoto lens gave me the background blur I wanted and the higher ISO setting gave me the ability to shoot at a higher shutter speed to capture some action.