Make It Your Own, ISO
I want to continue the Make It Your Own series by talking about ISO. We have covered Shutter Speed and Aperture as being two parts of the exposure triangle. The third part is ISO. Simply stated it is a measurement on how sensitive the camera’s image sensor is. The lower the number, the less sensitive the sensor is. The normal range for today’s cameras is 100 – 1600 . DSLR cameras with interchangeable lenses can go 12,800 or faster. The higher the setting, the faster the sensor is. What is the effect on the final image by changing the ISO. The main reason to use a high ISO is to be able to capture a low light image. The trade off of high settings come with a price as “noise” or “grain” is introduced into the image. The processors in today’s cameras are very good at reducing this effect, however we need to keep this in mind as the final image will be affected.
I took two different images of my Brownie camera. The one on the left was taken at ISO 400 . The one on the right was taken at ISO 4000
They look pretty close, but lets enlarge them.
You can see the grain in the image on the right. It is taking away from the quality of the photo, but may be the best shot to get in a low light setting.
Some General Guidelines
You would want to use a low ISO in bright situations (like sunlight) and a fast ISO in low light areas ( indoors / night ). The range starts at 100 and each time you double or halve the ISO, the exposure changes by one stop. So if you double it to 200, you would have to speed up the shutter or close down the aperture by the same one stop if you want the exposure to stay the same.
example: ISO 200 , 1/500 sec, F 5.6 = ISO 400 @ 1/250 sec. , F 5.6 ISO 800, 1/250 sec, F 8 = ISO 400 @ 1/250 sec , F 5.6
You need to take into account what you want the final image to portray. To capture action, you will want to keep the shutter speed high. As a result you will need to use a higher ISO, a wider aperture or both. In a low light setting, you will need to slow the shutter speed while keeping the aperture wide.
“Remember to Make it Your Own”