What is ISO in relationship to a digital camera?

My kodak z612 has an ISO of auto; 80, 100, 200, 400 and 800 manual. What do those numbers mean?

Its realtive to film ISO levels. If you havent noticed all film have an ISO level. The higher the number, the more sensitive it is to light. The lower the number the less senstive it is to light. How ever for digital it depends on how big the sensor is that will determine the imagine quality. The larger the sensor the less noise there is at high ISO levels. But yours is small so I dont think pictures will be usuable at 800 ISO.

how much light the camera lets in
the lower numbers give sharper pictures

In the days of film the ASA was the sensitivity to light. 200 was half as sensitive as 100 and so on. A common range was 80 - 800 some films even had 25 or 6400 however. now in the days of digital the ISO is the equivalent of ASA. The disadvatage of a high ISO is lots of noise the higher you go. most cameras look acceptable up to 400 or even 800. after that the noise isn't what atypical photographer wants. so if you can't get the shutter speed/ aperture where you want it you might haveto sacrifice noise to get a fast speed or high aperture in the 20's or 30's esp. in low light like theatre's. hope this helps let me know if you have any more q's.

the ISO is related to the sensitivity of the sensor to the light ... higher ISO # leads to increase the sensor sensitivity to light and consequently leading to improved results in dim light conditions which is something essential in low light photography....... the drawback of high ISO is the noise((grains)) which is very annoying especially if u have a camera with high noise level associated with higher ISO ....

ISO on a digital camera is meant to mimic 35mm film ISO.... in a sense.

For film, the ISO is the amount of light required to fully develop the picture onto the film. The lower the ISO the most light it takes to develop the image.

A higher ISO allows for faster shutter speeds for motion shots etc, but there is a considerable about of grain in the pictures. There are some programs which can help to remove this on digital pictures, but it will never be perfect.

The better the digital camera, the more features it will have of a 35mm SLR. (Cheapest camera just takes the pictures, the better the camera the more customization you can have in your pictures). This is why the better camera offer the ISO options. The sensor will become more/less sensitive to light just as the film does. Static noise is still however a side effect.

I always shoot on the lowest ISO possible (100 for me (Nikon)). I rarly go higher unless it starts to get dark.

So for your camera, stick to the 80-200 range for best image results for normal conditions.

Higher ISO numbers are used for action photos and low light conditions at a lower mega pixel range.

ISO is the sensitivity level of the sensor.

Higher number = more sensitivity.

"Auto" means when you're in auto mode, the camera will choose the sensitivity it thinks is best. It will select from 80 up to 400.

"Manual" means if you want 800, you'll have to select it manually.

This is usually because you'll get an unacceptably high level of noise at this setting and the camera doesn't want to take the blame ;-)

Hope this helps.