ISO part 3 of the magic triangle of exposure

Exposure in photography is controlled by 3 elements, I call this: 

The Magic Triangle

They are:

1. Aperture
2. Shutter speed
3. ISO setting

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Your ISO setting is an invaluable tool in your creative armoury.  


Why?


Q Have you taken photos at a party and discovered they were all blurred, not just because you had downed several beers?


Q  Or think a newborn's eyeballs would melt if you use flash?


This is why you need to understand ISO because it can get you out of some sticky situations. 

Warning: I'm not going to make this technically hot, just simply understood. 

ISO controls how much data or light your sensor records.  

Low ISO = accurate detail

High ISO = less detail (warning-may produce NOISE)

NOISE = made-up pixels to fill in the gaps that your sensor missed=not great

Settings ISO 2500 4 s f8

The colours were changing every few seconds, so to catch the image I wanted I set a high ISO of 2500, I still needed a tripod because it was a 4s exposure.

Note New cameras have sensitive sensors so you can shoot fantastic detail
at high ISO, and if you need this, they are worth every penny.

This Auricula was being buffeted by a stiff breeze.  You couldn't tell.  To freeze the image and get everything in focus I set the ISO to 640 the aperture to f16, the camera set the shutter speed to 100 s, rendering the shot perfectly.  This set is going to be featured in The Garden 2015.

Settings ISO 640 aperture f16 100 s

Note: Digital ISO is loosely related to film speed.  Fast films=high ISO=grain 
Grain is good, noise not so much.

Let me recall one final story for you. I was tutoring a photography group shooting summer flowers outdoors.  It was a gusty day, not ideal. Fred, was frowning at a beautiful rose.  He had set his ISO to 100-great for crisp, detailed shots, but impossible in a force 4.
  
Me:    'Why don't you increase the ISO?'  
Fred:  'Because, you don't get really detailed shots.'  
Me     'How many shots are you getting now?'
Fred   'None' 

The lesson: Ignore ISO at your peril.

Photography is a balancing act.  But now you know better.  Enjoy practicing, it really does make perfect.