ISO and what does it mean for cameras?


What exactly is ISO and why is it important in photography? ISO is an “indication of how sensitive a film was to light. It was measured in numbers (you’ve probably seen them on films – 100, 200, 400, 800 etc). The lower the number the lower the sensitivity of the film and the finer the grain in the shots you’re taking” (Rowse). The numbers themselves are also significant. Each time you double the ISO number, you need 1/2 as much light (assuming the same aperture/shutter speeds). The Nikon (camera manufacturer) website provides the following example: “So if you had a shutter speed of 1/250 at 200 ISO, going to 400 ISO would let you get the same exposure at 1/500 second (providing the aperture remains unchanged). This is why high ISOs are so often used indoors, especially at sporting events. Needing a fast shutter speed to stop action, photographers regularly choose ISO 1600 or above” (Nikon).

Rowse provides 2 example photos of the same object at 100 and 3200 ISO settings. I have modified these pictures to create a side-by-side comparison with the ISO speeds in white text.

Notice how the 3200 ISO has an increased “grainy” quality and that it appears to be brighter than the 100 ISO equivalent. The increased sensitivity to light on automatic settings will allow for recalculations on aperture and shutter speed. According to Rowse, “When you do override your camera and choose a specific ISO you’ll notice that it impacts the aperture and shutter speed needed for a well exposed shot. For example – if you bumped your ISO up from 100 to 400 you’ll notice that you can shoot at higher shutter speeds and/or smaller apertures” (Rowse).

As a general rule of thumb, ISO is one of the last things you will want to adjust when taking pictures. Think of a film camera, the photographer wouldn’t change out rolls of film with every shot! When we use our digital camera, we need to keep in mind: “When you increase the ISO setting, you’re not really making it more sensitive to light, you’re simply amplifying the light values it’s managed to capture…Usually, you don’t see it because it’s faint compared to the light falling on the sensor, but when you increase the ISO, you amplify it, and it shows up as a kind of random speckling. The higher the ISO, the worse the noise” (Meyer). A good rule of thumb is to try different aperture settings and shutter speed settings before adjusting your ISO sensitivity.

Works Cited
Meyer, J. (2014, February 18). What is ISO: Camera sensitivity settings (and the best ways to use them) | Digital Camera World. Retrieved March 11, 2015, from

Nikon. Understanding ISO Sensitivity. (n.d.). Retrieved March 11, 2015, from

Rowse, D. (n.d.). ISO Settings in Digital Photography. Retrieved March 11, 2015, from

Rowse, D. ISO Settings in Digital Photography. Retrieved March 11, 2015, from


Samuel Sanfratello

Samuel Sanfratello

My name is Samuel Sanfratello (Sam). I am a NY state dual-certified Mathematics and Special Education teacher and a nationally certified Consulting Hypnotist. I am also the proud owner and operator of two companies: Monroe Hypnosis and Rochester Analytics. I am a 2nd generation Spiritualist (American Spiritualism) and a certified Medium with the Plymouth Spiritualist Church (the mother church of modern spiritualism). I am an organizer of the Rochester Paranormal Researchers, founded in 2007 and a lead investigator for the Paranormal Science Institute’s F.R.I.N.G.E team. In my spare time, I give back to my community by doing volunteer work for my church and for my local chamber of commerce. I became interested in the paranormal when I spoke with a spirit in my grandmother’s house in the early 1980s. I enjoy reading publications and scientific articles about the fringe sciences and I enjoy sharing these understandings with others.
Samuel Sanfratello

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