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Originally Posted by greencreeper
Ah right. So at night you need a higher ISO.
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You got it!
Quote:
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Originally Posted by greencreeper
That screaming you hear is just my brain cells throwing themselves at the insides of my skull  |
Sorry...it get more confusing......feel free to ignore this too...
If you think of the experiment you might have done at school where you make a pin-hole camera...light passes though the hole and falls onto the paper to make the image.
So you could say that the paper needs 'x' much light to make the image right? Well the same is true of film and digital sensors too, where 'x' much light equals a correct exposure.
So there are several way to get 'x' into the camera. One is to use a wider aperture (if you look at the front of your lens you will likely see an 'F' and a number next to it). F is the aperture size, or the size of the hole to let light through. If you have a large aperture (small F number, like F/1.8) then you let in more light than a small aperture (big number such as F/36), so you can have a shorter shutter speed (the duration the shutter allows light in for).
You can also change the shutter speed to get 'x' through the lens, longer shutter speed = more light. And finally you can increase film speed, or ISO.
Which you use will depend on your camera, and what you're taking photos of. If you use a large aperture (big hole, small number), then you get less 'depth of field' - or in other words only the bit you focus on is in focus. So if you want a shot of your partner standing in front of a building - you focus on your partner, the building is out of focus. So what you'd do there is use a smaller aperture (bigger F number), bringing both into focus, but you'd need a longer shutter speed as the hole is smaller, and lets less light through.
If you're taking photos of fast sports, then you'd probably want the faster shutter speed, which would mean that you might need to use a wide aperture and/or a faster film speed/ISO (larger number). Higher ISO numbers mean more noise or graininess - which can sometimes be a good thing.
So all three are totally linked, there is a mathematic equation as to how they interact with each other but a) your head would explode and b) I still can't remember what it is! But in essence if you double your ISO speed, you halve the amount of light you need. The same goes for opening up the apperture by a full F/Stop (1 number does not equal 1F/Stop...go figure!) and the same for shutter speeds...if you double your duration of the shutter, you're letting in twice the amout of light.
Or of course you could just use the AUTO setting, wondering why half your shots are not what you thought they'd be!!!
Oh and if you're still confused, don't worry....it took three professionals explaining it in different ways for the penny to drop for me...but it's a good bit of knowledge to get your head round if you can!