ISO

19 Dec

What is ISO?

ISO is an international standard of sensitivity to light. Your camera’s sensor “sees” more light as the number goes higher. You will see more light at ISO 3200 then at ISO 100. The dark side is the fact that you will get more digital noise in your images at higher ISO. I don’t pay much attention to digital noise since I want my image. The audience will see the emotion or moment rather than the digital noise. You also have to be careful since higher ISO will cause a softer (not as precise and defined) looking images.

Why would you use a higher ISO?

You need a higher ISO to “see” more light inside and during sporting events to freeze subjects movements. Higher ISO in possible because the electrical current that passes through your sensor is higher and make the sensor more sensitive to light. You need to keep your shutter speed at a minimum of 1/125th of a second to proper achieve portraits. For landscape and architectural photography, I would strongly suggest to use a tripodand use longer exposition.

ISO 160

ISO 2500

How can you hide digital noise?

You can either use software to reduce digital noise if it’s unacceptable. Adobe LightRoom 3 is a great software for file editing and noise reduction.

TIP

To hide digital noise, insure that you use proper white balance and that you over expose your images by at least 1/3 of a stop. Improper white balance can cause you to underexpose your images by a full stop. Overexposing the images by a small amount gives you the latitude to bring the exposition down while editing your images hence hiding the digital noise.

Both the following images have been taken at ISO 2500.

Overexposed and corrected via LR3

underexposed and corrected via LR3

You need to learn about your best ISO to use the performance of your sensor to it’s limit. In a Canon DLSR you want to use 160, 320, 640, 1250, 2500, 5000, 10000, etc. For a Nikon DSLR, you want to use 200, 400, 800, 1600, 3200, 6400, 12800, etc.

I hope you enjoyed this little learning post. If you have questions, please feel free to write them in comments.

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