NEWBIE: Shutter speed, aperture, exposure and iso in relation to each other
This is a discussion on NEWBIE: Shutter speed, aperture, exposure and iso in relation to each other within the Exposure (ISO, Shutter Speed, Aperture) forums, part of the Photography Tips category; So, I just bought a Canon 5d and I'm attempting to get into photography. The hard part, learning the camera settings and what combination of ...
So, I just bought a Canon 5d and I'm attempting to get into photography. The hard part, learning the camera settings and what combination of settings produce what results. Where to put the shutter speed, aperture, iso, etc... for different conditions. Does anyone have a link or great article that could help me grasp this concept? Or, can any one of you explain this in a detailed way? I'm just confused where to set the shutter speed, aperture, iso, etc... in relation to one another.
Am I making sense?
06-01-2010 10:16 AM
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I've read a few, and I keep going back to this one.
“Try and penetrate with our limited means the secrets of nature and you will find that,
behind all the discernible concatenations, there remains something subtle, intangible and inexplicable.
Veneration for this force beyond anything that we can comprehend is my religion.”
Well, in a nutshell:
When you double the ISO, you half the shutter speed, so:
ISO 100 2 seconds
ISO 200 1 second
ISO 400 0.5 seconds and so on.
Aperture stops I am not too sure about though, but there is definitely a way of working them out
I guess like in most schools you should start with the "sunny rule" so you can get used to change the parameters for a determinated light condition ( day light only ) thenread about sorts of light ( daylight, artificial, reflected, direct, temperature of the light...and so on ) And finally google some about "The reciprocity rule" wich explains how to keep the exposuere compensated .I learn all this in my basic course at school , in this order, hope it guides you , cheers
Here is a good way to understand how each of the parameters inter-relate.
Think of the the desired exposure as tub of water. You don't want it to be too deep or it will be over exposed. But you also don't want it to be too shallow, or it will be under-exposed.
Think of the aperture as the faucet
Think of the shutter as how long you leave the faucet on.
Now there are also set standards for tub sizes set up by the International Organization of Standardization. These people like to sit around and put arbitrary sounding numbers on everything. They decided that a larger number denotes smaller tubs that fill up more quickly, these tubes are more "sensitive" to exposure than larger tubs with smaller ISO numbers. As a result, it is easier to use small tubs with larger ISO (like ISO 800) where the flow of water is less and big tubs with smaller ISO (like ISO 100) where the flow of water is more - that way you don't need to wait forever to fill it to the right depth. But the important thing for this example is that larger ISO numbers mean smaller tubs.
Lets say you will need to fill the tub exactly with 5 inches of water to make a proper exposure. How long will you leave the faucet on in any given sized tub depends on how fast the water flows through it.
So let's pretend that the faucet is marked with these funny numbers that don't mean much. They are technical information about the faucet itself and how much water it can push through at any given setting. But what we do know is that when it's all the way open it says f/2.8, which is a gushing torrent, and that the next number, f/4 runs half as much water through the valve and at it's lowest, f/22 it's hardly a trickle at 1/128th (i think) the flow.
Well, we don't want to be here all day, something could go wrong with the exposure if we did, so we'll start in the middle at f/5.6. Estimates from our exposure meter say that at f/5.6 it will take 10 seconds to fill the tub to a depth of five inches. But even that is a bit too long and something could happen in the meantime.
We have a choice now. One could increase the flow or finding a smaller tub. If we increase the flow by one "stop" to f/4, the water would be flowing twice as fast into the tub. It now fills in five seconds instead of 10. f/2.8 would fill the tub in just 2.5 seconds.
But if you liked how everything looked at f5.6 you'd need to adjust the size of the tub by setting the ISO. Above you were using an ISO 200 tub, which measures 20x20". It's pretty big and takes too long to fill. You could get an ISO 400 tub, it measures half as much at 10x10" and would take half as long to meet the 5" depth that you need. And a ISO 800 tub would be 1/4 the size at only 5x5", and wouldn't take much time at all to fill.
In fact if filling the tub quickly is vital, say for some reason the tub and the faucet and everything else is moving all around, you'd want a small ISO 800 tub and a fast faucet! So at f/2.8 and ISO 800, you'll get a proper exposure in just 1/8 of one second! If that still isn't fast enough, you'll need to contact the water company and have more water flowing through your faucet...
In case you haven't quite figured it out yet the water itself represents light, and the water company would then be your local hardware or camera supply store, getting more water would require more light, so you'd need a flash or some other light source to make the proper exposure at the desired shutter speed.
Anwway, I hope this helped. It might take a few read-overs to get it, but basically the principle is that they are all directly and linearly proportional to another. Twice as much light will require half as much time to get a proper exposure. Twice as much sensitivity will require half has much total light hitting the sensor over the length of the exposure. Everything has a drawback, however. DOF is decreased with increased aperture. Noise is increased with increased sensitivity. Motion blur in increased with increased exposure time. But it doesn't matter what equivalent exposure you choose, it will end up properly exposed, weather it's f/22 8s or if it's f/2.8 1/30s it does not matter.
bear with me. i don't have an escape button...
Originally Posted by Grandpa
Its very good - I have it too. Explains the relationships in simple terms together with some basic exercises in the first few pages.
Also, if you are in the UK, there is a very good article on Resolution Vs Depth of Field in this weeks Amateur Photographer; well worth the read.
check out this site:
not much reading involved, but a simulation of how different exposure settings interact with each other.
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