Photography Basics - ISO - mikecphoto

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Canon EOS 70D Digital SLR Camera with 18-135mm Lens

(at time of writing)

Lonely Planet's Guide to Travel Photography

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ISO determines how sensitive your sensor is. By increasing your ISO, you will essentially be adding gain/power to your sensor and allowing it to capture images with less exposure time.

ISO's generally range from 100-12800 (depending on camera), although more expensive cameras allow you to extend this from 50-102400.

There are pro's and con's to using different ISO's which I will go through in more detail below. First though I will explain what image noise is.

What is noise

Image noise is speckles of different brightness and color throughout pixels in an image. It is more noticable when you zoom in close to an image. Often when you print (in small sizes), the noise won't be noticable.

Noise is generally an unwanted aspect in a picture and it's always best to try and shoot so that you get as little noise as possible.

Example of noise

A low ISO is the best way to ensure your pictures contain minimal noise. When shooting in low light it can be hard to keep the ISO low, as well as ensuring images are sharp. Sometimes the only way to keep the ISO low will be to use a Tripod and have long shutterspeeds. See my night photography tutorial for tips.

High ISO

Having a high ISO will be useful for shooting in low light when you can't use or or don't have a tripod. Examples such as bars and busy streets at night are examples. Also on a cloudy dark day you may also need to increase the ISO to a higher number.

By having a high ISO you can shoot at higher shutterspeeds, but the negatives are that you may get image noise in your image, which may be ok if you're not printing your images in large sizes or selling your images.

Sometimes even if it's a bright day you may want to increase your ISO so that you can get even faster shutterspeeds for shooting things such as flying birds, vehicles etc.

Recommended Settings

I will generally always keep my ISO at 100, especially when shooting at night on a tripod. If I need a faster shutterspeed and I don't want to increase the aperture, or there just isn't enough light for a faster shutterspeed I will also increase the ISO. Sometimes I also set the ISO to auto but with a limit on the camera so that it doesn't go too high such as a max of ISO 1600. I shoot with the Canon 6D which has this option. Not all cameras will have this feature though.

One thing to keep in mind if you're taking taking pictures for yourself (ie not for clients), is that if you can't get a sharp picture without increasing the ISO, then it's best to increase the ISO and have a noisy picture than not get an image at all.

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