What exactly is ISO in respect to digital cameras?

Question

I'm looking into getting the Canon A700, and when looking at sample shots from http://www.steves-digicams.com/2006_reviews/a700_samples.html the photos in ISO800 and 400 are very grainy/noisy- why is that?
Is this something that I should look past, or take into stronger consideration?

Answer 1

ISO ratings determine shutter speed and lens openings.

They are basically regualted by sensor limits and in the case of high ISO numbers sensor elements could be paired or even qudrupled (which means a drop in resolution).

ISO is senstivity to light.

It used to be called ASA.

It's eqivalent to a half or full "f stop" of light.

It's basically, to a digital camera, what a volume control is to a walkman.

A low ISO (100, 64) is like turning down the volume (senstivity to light).

While a higher ISO (400 or 800) is volume (senstivity) full on. This means you can take pictures in lower light, such as inside a building withouyt flash or on the streets at night.

A very high ISO (1000 or 1600) can mean a reduction in resoutltioni becaue 2 or 4 pixels are used to boost the light gathering power.

In photographic film ISO is directly related to the size of the grains of silver. Larger grains are more senstive to light, while smaller grains are less senstive and provide finer detail, especially in enlargments.

The CMOS/CCD sensor of a digital camera has both an upper and lower threshold. The ISO setting is like a volume control.

At ISO 1600 you may have problems shooting a beach or snow scene in daylight, because the camera can't stop down the lens or make a fast enough shutter speed.

At ISO 100 you can't shoot in lower light, such as in a house with house lights.

A higher ISO makes the shutter speed go faster (for action) and a lower ISO makes both the shutter speed slower and the lens opening (F stop) larger. This is for low light.

Answer 2

For a customary element and shoot digital camera (not DSLR) taking photos outdoors in brilliant sunlight you may choose your ISO placing as low as ought to correctly be reckoning on the digital camera. some bypass as low as sixty 4, or 80, or one hundred. As mild receives dimmer you develop ISO placing to both three hundred, or four hundred. As a minimum of one answerer stated because a digital camera's ISO volume is going to 1600, it really is all hype. it will be a ineffective shot at that volume, fairly blurry. some cameras, yet not very many enable you to shoot larger than a four hundred ISO, yet frequently do not bypass over four hundred on a level and shoot digital camera. So, ISO is your digital camera's sensitivity to mild.

Answer 3

ISO is exactly that: the quality of the captured image on digital "film"; no different from camera roll film. ISO of 400, generally, is the "all-purpose" exposure setting--purportedly suitable in BOTH natural and artificial (flash) lighting.

ISO 800 is for your images in darker settings, best used with a tripod and remote shutter release.

ISO 100, in my opinion, is the best setting: it's to be used with flash lighting. With a tripod, you can take a picture WITHOUT a flash, and get a pretty decent/perhaps dark--but clear non-grainy image.

Answer 4

Came here expecting to answer the question but it seems "Earl D" has said it all. He absolutely spot on. Follow what he says.

As a thumb rule, use higher ISO settings for low light conditions but avoid anything greater than 400 unless absolutely necessary.

Answer 5

Speed of film settings. The film for the film cameras came with varying settings. 64, 100, 200, 400, 800 ,1600. 200 thru 800 is for general purpose. 1600 is fast film while 100 is slow. It is useful in different situations depending on light and conditions. If you are into effects, it helps.

Answer 6

ISO Denotes is how sensitive the image sensor is to the amount of light present. The higher the ISO, the more sensitive the image sensor and therefore, the possibility to take pictures in low light situations.