# What is Camera Noise?



## Buszaj (Jun 20, 2007)

Hi everyone,

I've come across this phrase a lot in the forum. What on earth is "camera noise"?

Thanks a lot


----------



## Seefutlung (Jun 20, 2007)

"Camera Noise"? Maybe the sound the shutter makes when it is released???

Just plain ol' "Noise" in digital photography, typically is associated with higher ISO ratings. When one increases the ISO, (increasing the ISO makes the sensor more sensitive to light ... the greater the sensitivity the less light is required for a proper exposure), one of the trade-offs is a lowering of Image Quality (IQ) in both contrast (higher) and noise (more). Noise looks a lot like "grain" in film photography.  The higher the ISO the larger and more visible the noise (grain).  Noise is also visible in under exposed images or in the shadow areas of properly exposed images.  

Cameras handle noise differently. Canon's 1D series, 20D, 30D and 5D seem to be the best at dealing with noise at elevated ISO and in the shadows. Sony CCD sensors in particular seem to do a poor job with noise and I know a few people who won't use their Sony Sensors at ISO 800 or higher (some Pentax and Nikon users).

Noise can also be attributed to hardware design. The 10MP XTi has more noise at elevated ISOs than the 8MP XT ... due to cramming in more pixels in the same sized space. This "pixel cramming noise" is especially noticable in P&S cameras which generally have an even smaller sensor size than cropped sensor dSLRs. The converse example of this is the 5D, a full sized sensor (same size as a 35mm film frame) which has one of the lowest noise ratings of any digital camera.

Remember that noise effects IQ, the greater the enlargement the more prevelant the noise. 

Gary


----------



## Big Mike (Jun 20, 2007)

That's right.  'Noise' has to do with the quality of an image.  Noise is visible as specs of color that shouldn't be there.  It can be compared to film grain (grainy photos).

Digital noise could be a result of a bunch of different things.  For the most part, it become more visible when you use a higher ISO setting.  This is because when you turn up the ISO, the camera amplifies the electronic signal...which causes distortion...which becomes the noise we see in the image.

This is why it's best to keep the ISO as low as possible.  However, it is sometime necessary to turn up the ISO...mainly when the light levels are low and we want to get a faster shutter speed to help freeze camera or subject movement.  Shooting fast moving subjects (even in brighter light) is another time when turning up the ISO may be a better choice.  

Typically, it's easier to deal with noise than a blurry photo.

There are ways to remove or reduce noise in digital images.  Neat Image and Noise Ninja are two good programs.

I just found THIS article.


----------

