What The F/ Stop?
"I'm just going to take it down a stop or two" is something that most photographers utter every time we take an image, but just what are we talking about? What is a stop?
OK guys and girls, time for a little refresh I think.
We have already found out how camera's really work, so this will serve as a little reminder and a nudge in the right direction.
So, just what exactly is a stop? And why would we want to "take it down a stop or two"?
A stop is merely halving or doubling the amout of light during an exposure. And that is basically it, my friends!
So, when a photographer says "take it down a step or two" What he or she really means is, he will be halving the amount of light during an exposure.
And if he is taking it up a stop or two, it means doubling the exposure.
Now, if you were paying close attention to How A Camera Really Works, and if you were'nt, then you should go henceforth to the naughty step, but if you were paying close attention, and I know you were, then you will remember what three things give us an exposure, ISO, aperture and shutter speed.
So, if your working at ISO 200, with a shutter speed of 1/125 and an aperture of f/5.6, and the scene is too dark, you might want to take it down a stop or two. Using the shutter speed means it goes from 1/125th down to 1/60th.
Or you could just up the ISO from 200 to 400, that would make the sensitivity more sensitive.
Or you could increase the aperture from f/5.6 to f/4, either way, it is a full stop's worth of light entering the camera.
Take the above settings again, and say we want to take it up a stop, we will either go from a shutter speed of 1/125th to 1/250th, or ISO 200 to 100. or f/5.6 to f/8. Either one of these will give you a full stop's worth of light during an exposure.
So there you have it, that's all Stops really are, and like everything else in photography it does make sense in the end.
I do hope I am explaining all this clearly enough to you guys and girls out there, but it is important to clearly explain what all these things mean, and photographers using and talking about stops is a common occurence,
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