What Does ISO Mean? How Does it Affect my Photos?

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JGaulard

JGaulard

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I am going to keep this post short and sweet. ISO can end up being a huge topic and for a beginner, people tend to talk about a lot of stuff you have no interest in knowing. I'll keep what I write limited to the basics.

To start off with, I'll tell you that ISO is an acronym. It stands for the International Organization of Standardization, an organization that has to do with camera sensors and their measurements. It's an old acronym that's been carried over since the good ol' days of film. You don't need to know any of this. It has no impact on your photography.

What you do need to know is how ISO affects the photos you take. In general, low ISO values on your camera are good. The lower your ISO setting (100-200), the more normal your camera sensor's sensitivity. The lower the sensitivity, the less noise or grain in the resulting photo. As you increase your ISO value, noise or grain is introduced into your photos as small specks or tiny little dots. You don't want this. Noise is bad.

Why would you want to go from a normal sensor sensitivity to a higher one? Well, if you're taking photos in bright daylight, your camera's normal sensitivity is fine. There's tons of light to enter through the lens and you don't need to compensate for anything. It's only as you enter darker, lower light environments that you may need to crank up the sensitivity. Say you're in a dark room and your photos are coming out underexposed (dark). If you increase your ISO value, the sensor will become more sensitive to light (like an amplifier), which will, in turn, brighten up the photos. This brightness comes at a price though. That price is grain. So there's always a trade off. Just remember, the lower the ISO number on your camera, the better.

I've written a few posts on the blog that have to do with ISO, what it means, and how it works. Take a look at them by clicking through below. I was quite thorough, so they may be very helpful if you're interested in leaning more about this topic.

Understanding Basic Camera ISO Settings
When Should I Change My ISO Setting?
Photography Basics: Shutter Speed, Aperture & ISO
 
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mariah

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Thanks for explaining ISO beautifully. So what you want to say is that the lower the ISO the better my camera is. Does ISO have to do anything with lens? or the camera itself?.
 
JGaulard

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mariah said:
Thanks for explaining ISO beautifully. So what you want to say is that the lower the ISO the better my camera is. Does ISO have to do anything with lens? or the camera itself?.
Hi - ISO is a setting inside of the camera, not the lens. all it does is make the camera's sensor more or less sensitive to light. In general, using a lower ISO can garner higher quality photos, but not all the time. I recently took some star photos at night and was forced to use an ISO value of 400 because if I didn't, the shots would have come out too dark. I would have loved to have used an ISO value of 100, but if I did that, I would have had to slow down the camera's shutter speed, which, in turn, would have caused some star trails, which I didn't want.

So adjusting ISO value isn't an indication of how good your camera is. It's more of an exposure tool that you can use to moderate between the aperture and shutter speed.
 
What Does ISO Mean? How Does it Affect my Photos? was posted on 02-12-2020 by JGaulard in the General Photography Talk forum. Click to visit our most recent posts or return to the photography forum homepage.

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