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Old Feb 6, 2007, 3:54 PM   #1
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I'm pretty new to digital photography and have only used point and shoot digital cameras. Years ago, I have taken a couple courses years ago, but that was strictly film. (actually I don't even know if digital photography existed) In doing my homework to by a new camera (I've pretty much decided on the Canon S3 IS), I came across noise. I know noise is often "off" colors of things like the sky or tree lines, but most explanations don't include great shots of noise. So, does anyone here have some good examples of noise in pictures? Is there a really good web page that points out these problems an offers ways to avoid them?

Thanks in advance.


Greg
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Old Feb 6, 2007, 4:16 PM   #2
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noise is pretty much the equilalent of grain in film photography. It really doesn't have much to do with colors other that the fact that it shows up more in darker areas of the image.
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Old Feb 6, 2007, 4:22 PM   #3
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Ok, I can see that. That would also explain why it is mentioned more at higher ISO settings.

I've also seen some articles about getting a purplish color in the sky and calling that noise. Would that be something a bit different?
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Old Feb 6, 2007, 6:03 PM   #4
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fritz,

There are different types of noise in digital pics. Basically, it shows up as specks. Here are some examples:

http://www.dpreview.com/reviews/fuji...00fd/page6.asp

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Old Feb 6, 2007, 8:58 PM   #5
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fritz, if you want to minimize noise, shoot at the lowest ISO you can by with, avoid long exposures (say, 1/15 sec. and under) and try not to underexpose.

Of course, even doing all that, you'll still get some noisy photos -- everyone does -- which is why there are noise-reduction programs. Some, like Neat Image and Noise Ninja have free versions that are somewhat limited over the purchased version but give excellent results.

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Old Feb 10, 2007, 12:35 AM   #6
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Fritz,

The best way to minimize noise is to not have it in your picture at all in the first place. (Harder said than done) While some computer programs can take away the noise that may occur in your photos, a noise free picture the first time is much better and here's why.

Noise occurs when there is not enough light for the camera's CCD sensor(kinda like a digital film chip) to "see" what to take, so it increases the ISO, or sensitivity, so that it can take a picture that is bright enough. Thus, one of the only places most people see grain and noise is in dark settings like at night or in a dark room like at a party, and in most cases, any ISO over 200, grain is noticable. The good news is that there are two ways to fix this:

1) Use the Flash

By creating more light for the CCD chip to "see," the decrease of ISO is no longer needed.

2) Increase your Expose Time

By increasing your exposure time, that same CCD chip has more time to take in more light, like leaving the shutter open on a traditional film camera that you're used to. Any exposure over 1/60 of a second without Image Stabilizer or a tripod could have blur, so be careful.

:-)Let us know how everything goes! :-)

-=Greg=-
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Old Feb 10, 2007, 9:21 AM   #7
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Here's a b/w shot with noise; I think I actually added some noise in pp because I liked the look:



Here's a pretty noisy color image--lots of noise; I turned off all NR in post production as part of a test of a developer; the yellow noise is particularly problematic:




Got the idea?

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Old Feb 19, 2007, 5:56 PM   #8
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Sorry I didn't reply quicker to this. Work has been pretty hectic over the past 2 weeks.

Thanks for all the information on noise. I'll keep some of the techniques in mind for avoiding it in the first place. I usually don't mind using a flash for indoor pictures, so that's not a problem. I've also found that over all, the S3 seems to give some pretty natural looking skin tone when using the flash, so that's also a plus.

I really appreciate the pics with the noise. They really point out exactly what you are talking about. It looks like the darker parts of the picture, like shadows under the chin, tend to get a lot more noise. I'll have to play around with some software in case I get a particularly noisy shot.

Thanks again.

F_M
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Old Feb 21, 2007, 2:22 AM   #9
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I should emphasize that that image is a 100% crop out of a larger image, so you're unlikely to notice noise that bad in an ordinary shot.


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