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ISO, What is ISO...

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  • ISO, What is ISO...

    Whilst looking at a way to describe what ISO is, within a cameras operations, I came to the discovery that I do not actually know what ISO is an acronym for, and upon researching this, it became quickly apparent that a lot of photography websites I've looked at, do not elaborate on what ISO actually stands for.

    ISO is the acronym for the organization that sets standards internationally. There name is the “International Organization for Standardization”. The reference of ISO has been around since the 1980s after it superseded what prior to the 1980s was known as DIN. For the entire story on the history of ISO, please view the following wikipedia article, which is extensive and quite complex.

    So what is it? We now know it's just a word that represents an organization that sets standards, but what standards did they set, and why reference them in the world of my cameras digital software? The standards that are set by the organization are the levels of sensitivity that an image sensor works. Within most cameras today, you'll often expect to see the following as your levels.. 100, 200, 400, 800, 1600.

    The effects of setting the ISO levels on your camera, are that you'll be making the image sensor inside either more sensitive or less sensitive, which in return can effect the speed of your camera. The question that you really need to think of though, is why would you need to adjust such a sensor? Well the affects are different to what you'd get if you adjusted the aperture and shutter speed, because with the ISO being set to 1600, your aperture could be set to 2.8 and your shutter speed to 1/16th of a second, but if you have your ISO set to 200, then this will reduce your shutter speed, and possibly make it 0.5 seconds.

    Here's an example of when I'd use it. I'm at a concert, and I'm not allowed to my flash so I have to think of another means to get the image I want. I have set my aperture to 1.8 so that I can only focus on the singer, and I've got my camera to 1/100th of a second for shutter speed, but it's way to dark, and the only way I can get the image exposed enough, is by setting the camera to 1/4th of a second, but this is causing issues, because the singer is never standing still, and my photographs are blurring. What can I do? I'd drop the aperture to 800, or 1600 and then theoretically the shutter speed should be faster, as the sensor is being exposed to light just that bit more to create a difference.

    This sounds great doesn’t it, but there is one very big negative to having a high ISO setting, and that is the intrusion of noise within your image. Noise alone is enough to destroy and image if you're planning on printing it on large scale, but it also make the camera almost look as though it's not functioning to well, to anyone who is not adept to the photography world. If you're asking yourself, what is noise, then don't worry, there should be a tutorial on the website somewhere.