ISO settings Vs shutter speeds

Think I've got to the bottom of this 'ISO' thingmebob.

Excuse my stunning examples but it's persisting it down so I only went as far as the back door.

Anyhow - first up I took two pictures of a dog bowl. The first shot was ISO 200 & the second ISO 1600. The shutterspeed for both pictures was 1/160. At that speed the extra 'sensitivity' of ISO 1600 has produced a lot more light.

ISO 200 @ 1/160


ISO 1600 @1/160


The second example is pretty much the same. The first shot is ISO 200 and the second is ISO 1600. The shutterspeed this time is 1/100. Again the ISO 1600 has produced a much 'lighter' picture.

ISO 200 @ 1/100


ISO 1600 @ 1/100


Then the penny dropped (took a while I know) and I realised I needed to take four pictures not two. Bare with me coz i'm trying to get this straight in my own head.

I pointed at the plants and took two 'pairs' of images.

First I tried an ISO 200 shot and a ISO 1600 shot at a quicker 1/400 shutter speed.

At this shutter speed - the ISO 200 is not getting enough light but the ISO 1600 is.

ISO 200 @ 1/400


ISO 1600 @ 1/400


Then I took an ISO 200 shot and an ISO 1600 shot at a much slower 1 second shutter speed.

At this much slower shutter speed the ISO 200 is getting an OK amount of light but the ISO 1600 is getting far too much.

ISO 200 @ 1 second


ISO 1600 @ 1 second


What did I learn ?

A higher ISO enables you to get the same result as a lower ISO but with a faster shutter speed. - that's why we used to buy higher ISO rolls of film for 'action' shots

Please tell me i'm right



.

Yep good tip

Higher ISO = more light (so good for pics where lighting is poor)
Longer Shutter Speed = more light (so again good for pics where lighting is poor)

However,

Higher ISO adds a bit of noise, so the higher you go the more noise you'll get
Longer shutter speeds do not add noise, however, if things are moving, you'll get blur - as the shutter is open longer (so ideal for 'static' shots such as landscapes, and creative ones like softening the water in a waterfall, cityscape shots with cars lighs blurred etc)

I hope I am right too

Very good Azz

Super examples Phill

bumped for a frequent guest who asked me.

Get them to join up Phil

Now what is the general rule? the ISO should be more than the max mm of the lens ?

I can't remember.

Bazza

Nope thats your shutter speed
Generally you need a faster shutter speed than the focal length to avoid camera shake.

ISO allows you to use that faster shutter speeds in dark situations by increasing the cams sensativity to light

HTH

For still subjects - use a tripod. Tripods allow you to use far longer shutter speeds than your focal length. With slower shutter speeds (no shake) you don't have to crank up the ISO settings for shooting in low light.

Thanks K. I was having a senior moment and just couldn't remember which was which.

Bazza

I find this a helpful topic, but please can someone tell me what 'noise' is in photography terms?