I dont really understand about noise

Maybe some one can explain in very simple terms, what noise is and why it occurs, I know it occurs when the ISO (do you say I S O or eyeso?) is higher, it was 500 for this shot with my nifty fifty and 30d., the light was poor and I had a fast moving kitten so it seemed like a good idea to up the ISO. I shoot manual mode with : Exposure: 0.025 sec (1/40) Aperture: f/2.8 Focal Length: 50 mm ISO Speed: 500 Exposure Bias: 0/3 EV Flash: Flash did not fire

In this picture the noise /graininess is much more apparent in the back ground, I assume this is because the cat is textures, how ever the basket handle is fairly smooth and does not appear grainy. Is the amount of noise in my picture acceptable? when i view at 100% i dont think it looks good)

I am going to be buying the book understanding exposure in the near future, which should stop me asking silly questions!

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I'm new around here, but I would also say that camera shake comes into play here looking at your EXIF data. The 30D is a crop body so if u have a 50mm lens on there you should probably only shoot at 1/80 or above

My take on it is that it's the focus point... Several areas are in perfect focus, others are not - but that has more to do with the focal length, I believe, than "noise".. nice pic though.

That is one cute pic!

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In this picture I don't see any noise at all, just the for/background blur due to the shallow Depth of Field.

Hermeto wrote in post #5481283
In this picture I don't see any noise at all, just the for/background blur due to the shallow Depth of Field.

The nifty fifty provides great bang for the buck,but isn't known for the creamiest bokeh.
I agree with Hermeto.
It's a nice capture, don't pixel peep what isn't the focal point of the photo.

Ok thank you, Im still learning, so its hard to know whats good and whats not, I am saving for the 50mm 1.4 does that give smoother brokeh?

What is the actual cause of noise?

For a given camera, the better the exposure, the less noise you'll see which also means that the darker areas will usually show more noise than the lighter ones.

ISO 1600 EXIF is included in:
The Johnny Headband Band

Gavin shoots a lot at high ISO & provides fun captions as well.
The week's sporting events in images...

ISO 3200 EXIF is included in:
Barbara Payton @ ISO 3200

Barbara Payton & Her Band @ ISO 3200

rachelsne wrote in post #5481664
What is the actual cause of noise?

AFAIK the camera boosts the power to the sensor when you boost the ISO a lot, which can cause artifacts to appear. They're more apparent in darker areas of the photo as that's the part that's usually boosted more.

Different cameras of course can handle higher ISOs better. My SIL's Canon S3 was horrible, the 5D is the tops

The actual cause of noise is the quality (or lack of quality) of the semiconductors used in the various parts of the camera.

Cameras are a combination of analog and digital circuitry The analog circuitry is the first thing the "image" passes through. All analog circuitry has a background noise level inherent to that particular circuitry. (Think of this as the background hiss in a radio, which is where the term "noise" comes from.) Better circuitry has less noise, which is the biggest single reason that less expensive cameras have more inherent noise than the more expensive ones.

ISO (usually pronounced as three letters: I-S-O) is effectively gain. When you increase gain, you increase the level of the inherent noise in the circuitry. This is why high ISOs have more noise than low ISOs.

Various things affect the amount of inherent noise in a circuit. Temperature is probably the most obvious. The higher the temperature, the greater the noise.

Light also affects noise. The greater the average light falling on a sensor, the greater the noise level of that sensor. It is fortunate, therefore, that bright areas tend to mask noise (just as a loud passage masks the background hiss of a radio). A sensor with a high average brightness, however, will show increased noise in its darker areas.

^ Yeah... what he said

rachelsne wrote in post #5481011
the light was poor and I had a fast moving kitten so it seemed like a good idea to up the ISO

It was a good idea, it's a nice image, and the noise is not objectionable. (I don't see it at this size even )

It might show up at 100%, but I doubt it would show up in print.

That's a great pic. It may look better printed out than on a computer screen. I don't see any noise (or very little anyways)

Rachel, I think your cat shot has two things going for it.

First, it is a good exposure, and has relatively little noise. I agree with those who say it will probably look much better printed that it does on screen.

Second, and, in my opinion, far more important, it is an excellent composition. A good composition can easily "save" a picture that may not be technically perfect. The reverse is definitely not true.

My problem is that my pictures were usually technically perfect, but lifeless. That is why I am not a photographer. I have no eye. Don't have much of a soul, either.

Give me a picture that lives any day of the week!

20droger wrote in post #5481919
The actual cause of noise is the quality (or lack of quality) of the semiconductors used in the various parts of the camera.

Cameras are a combination of analog and digital circuitry The analog circuitry is the first thing the "image" passes through. All analog circuitry has a background noise level inherent to that particular circuitry. (Think of this as the background hiss in a radio, which is where the term "noise" comes from.) Better circuitry has less noise, which is the biggest single reason that less expensive cameras have more inherent noise than the more expensive ones.

ISO (usually pronounced as three letters: I-S-O) is effectively gain. When you increase gain, you increase the level of the inherent noise in the circuitry. This is why high ISOs have more noise than low ISOs.

Various things affect the amount of inherent noise in a circuit. Temperature is probably the most obvious. The higher the temperature, the greater the noise.

Light also affects noise. The greater the average light falling on a sensor, the greater the noise level of that sensor. It is fortunate, therefore, that bright areas tend to mask noise (just as a loud passage masks the background hiss of a radio). A sensor with a high average brightness, however, will show increased noise in its darker areas.

Just wanted to add a couple of things to this: in simple terms, when you push the power to the sensor, you increase the chance of a false reading by each of the sensor dots. These false readings are where a sensor records red, but actually that part of the image is black (for example). This is the noise.

I pronounce it as a word: eye-zoh.

In some pictures, fine noise appearing as speckles can enhance the picture. I use Noise Ninja, and it's awesome, but as I say, there are times where I think that the noise actually contributes to the art of the shot. But if it's appearing as blotches, get rid of it.

Finally, if I were looking at your posted picture (at its posted size), I probably wouldn't be moved to run it through Noise Ninja.