NOTE: This post was originally published on the blog, “Simply Horse Crazy”, by Mary Coleman, on November 11th, 2013. She also took many of the photos included, except where credited otherwise. Huge thanks to Mary for letting us post her series here.
So, what is ISO?
Technically, “ISO” stand for “International Organization of Standardization” (to me, I feel like it should then be IOS not ISO but whatever…it’s a European based org). To understand why ISO is called ISO, we have to briefly venture into the world of film photography…
In case you had not guessed, the International Organization for Standardization deals with…well..standards. Before digital photography, when film was the primary component to picture-taking. ISO dealt with the speed of the film (and therefore the ability to take pictures in areas with less light). Today, when film photographers number less and less every day because digital photography is cheaper and easier (trust me on this…developing film is a cool process, but man, is it work intensive!), ISO still applies. In the most basic sense, ISO deals with the camera’s sensitivity to light.
The higher the ISO, the more sensitive the camera is to light.
The lower the ISO, the less sensitive the camera is to light.
ISO on most cameras ranges from 200-3200 (mine goes from 100-6400…some camera can go as low as 50 to even all the way to 204,800), with each increase in value doubling the camera sensor’s sensitivity to light – which means that ISO 800 has double the sensitivity than ISO 400, ISO 400 has double the sensitivity to ISO 200, etc.
How Does This Apply?
Say we are in an indoor arena (let’s apply to something relevant to all of us, shall we?) and it’s pretty dark. The horse and rider are cantering around the indoor and you want to have shots that are in focus so you bump your shutter speed to around 500 (1/500 of a second). All excited that you think you got *the shot*, you look down at the view screen of your camera and you see this:
And immediately you’re like “WTFWHYDIDN’TMYSTUPIDCAMERATAKETHEPICTUREIWANTEDITTO??????”
You go home convinced that it’s impossible to take good pictures in an indoor arena…until your friend shows you the pictures she’s taken indoors:
One of the 3 major keys to this scenario lies with ISO. The first key is shutter speed, which I already explained…the last – and arguably most important – key will have to be saved for another day. If you bump your shutter speed up to 1/500, you CANNOT be taking pictures in low light and expect to leave your ISO on 200. Depending on the lens you have (the last variable we haven’t talked about yet), you might be looking at an ISO of 1600.
Unfortunately, just as low shutter speeds have the side-effect of blur, high ISO values have the side effect of “grain” or “noise,” as seen below:
…and again here below:
The first picture was taken outdoors with lots of light available (probably with an ISO range of 100 or 200). The second picture was taken in a very very dark indoor with an ISO of 6400. Clearly the first is a much better quality picture. There was nothing I could do to salvage the second picture, it was just too grainy.
So here’s the two rules of thumb that I (usually) go by:
- Always use the lowest ISO possible (unless for some reason your going for the “grainy” look)
- Never go over ISO 1600.
How Do I Change My ISO?
It’s simple, really (remember, my instructions are Canon specific…sorry to everyone else!). Most likely, you’ll find a button on the top of your camera, labeled ISO. Pressing that button will bring you to a screen that shows your available options. This screen will allow you to scroll through your ISO values and choose what you need for that shot. You can also choose AUTO ISO, but I’m not a huge fan. If your camera doesn’t have the ISO button easily accessible, here’s where reading your manual comes in handy!
Tune in next time for Part 5!