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Old Aug 9, 2004, 8:47 AM   #1
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Please excuse my ignorance/inexperience but what do you guys mean when you say that a camera has noise? Are you referring to the picture that is taken?


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Old Aug 9, 2004, 9:04 AM   #2
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Noise refers to electronic interference that you notice when you look at the print. As you increase the sensitivity of the CCD/CMOS (higher ISO numbers), you increase the liklihood of noise, particularly in shadow areas. It becomes even more noticible as you increase the size of the image. Different camera manufactures and even models have varying thresholds regarding when noise becomes apparent. It can be removed to some extent using post processing tools. It is similar to what is known as "grain" in film.
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Old Aug 9, 2004, 9:13 AM   #3
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There is no such thing as a dumb question.

When people refer to noise, they are talking about artifacts found in their photos. High noise is a bad thing. Generally, the higher your camera's ISO setting the more noise you will get.

In 35mm cameras, you change your ISO by using faster/slower speeds. You can get ISO 100 (daytime), ISO 200, 400, 800, 1000+ films. The faster speed films will give you grainier photos. This is due to the emulsion layer, and how it was manufactured to be more light sensitive. Thus, faster ISO allows you to take photos in lower light conditions, but with a penalty in photo quality.

Well, with digital cameras, if you select a higher ISO, all this does is make the photo sensor more sensitive to light. This is done electronically. If you go high enough in your ISO settings, you will get signal interference, etc, that will show up as grain on your digital photo much like 35mm film.

Thus noise = grain.

People select higher ISO so that they can get acceptable shutter and aperture speeds in low light conditions. Some digital cameras are better at low light photography then others. This is due to several issues. The electronics, the size of the photo sensor area, and the programming used that operates your camera. Some cameras have noise removal features. Some work by doing it as you shoot, others work by taking a second photo with the shutter curtain or mirror down, thus allowing it to remove the oddnoisy pixels by using the black second frame as a guide.

Hope this helps.
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Old Aug 11, 2004, 6:54 AM   #4
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Just to add, increasing ISO on a digital camera is like turning up the volume on a radio tuned to a poor quality station...you not only increase the signal but you also increase the static.
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