What The Fudge Does ISO Do?

Joosh · Low User Joined: 13 Oct 2006 Posts: 41

On my compact, there are 5 ISO settings and i was wondering if someone could help me as to what they did

Auto - im guessing fairly self explanatory
50
100
200
400

they have always been there and i have played but i dunno what they do...

thanks,

Joosh

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duncan_g · Posted: Fri Oct 13, 2006 4:28 pm Post subject:

My small knowledge is that if the ISO is low it is best for bright daylight type things. And a high ISO is best for darker, but it will be grainy.

Joosh · Low User Joined: 13 Oct 2006 Posts: 41

ok, but what does it actually alter?

i mean i would rather understand what it did and then use it than just know that its good for daylight/nighttime

not a dig btw

Joosh
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Henry · Posted: Fri Oct 13, 2006 4:59 pm Post subject:

Its started with how sensitive the film was, you can buy different grades of film, and it has translated into how sensitive the sensor is on digital cameras.

Joosh · Low User Joined: 13 Oct 2006 Posts: 41

ah ok, so is it kind of the higher the number the more light the film absorbs?

Joosh
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Henry · Posted: Fri Oct 13, 2006 5:27 pm Post subject:

No the quicker it absorbs it. I normally leave my ISO on 200 for day to day, and always use 200ASA(like ISO) film.

Joosh · Low User Joined: 13 Oct 2006 Posts: 41

ah ok i will play about

thankyou all

Joosh
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dandantheadminman · Posted: Fri Oct 13, 2006 5:59 pm Post subject:

yeh, most of the time, whooting biking (in the forest) I have it on 200 cause trees block out some of the light,

it depends on the camera as to what iso you can get away with without it getting too grainy.
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Roo · Forum Master Joined: 16 Aug 2006 Posts: 442

Yeah, as explained above, ISO/ASA is just an international standard number to show the speed of a film, or the equivalent sensitivity of a digital sensor.

50iso is not very sensitive, therefore you need a larger aperture or slower shutter speed, 3200iso is very fast so you take take pictures with a fast shutter speed even in low light, but the faster the ISO, the more grain/noise you will see (the multicoloured dots in coulour pictures)

fozzybear · Posted: Fri Oct 13, 2006 6:17 pm Post subject:

ISO is the rating assigned to how sensitive the sensor is to light..

the higher the iso the more sensitive the sensor is to light, the higer the iso the more "noise" is produced during the process of taking the photo... if you want an explination of why and how post again and i can dig out a full scientific explination.

Hamish · Forum Veteran Joined: 29 Sep 2006 Posts: 1011

As the others have said the ISO is basically the film sensitivity.

The exposure (i.e. amount of light needed to get a photo looking correct and not too bright or dark) depends on only 3 things - aperture, shutter speed and ISO. I could explain it all but it'd take ages and I cant be bothered. I'd suggest that you look up a tutorial on exposure and it'll explain it all.

this might be a bit much but it'll give you an understanding:

http://www.luminous-landscape.com...g-series/understandexposure.shtml
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dandantheadminman · Posted: Sat Oct 14, 2006 11:01 am Post subject:

nice link Hamish, thnx for that

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