ISO and shutter speed seem to be the same thing: they have to do with light entering the lens... and what%26#039;s aperture? any good websites that i can learn from?
What%26#039;s the difference between ISO, shutter speed, and aperture?
ISO refers to the sensitivity of the film to light. Each film will need a certain amount of light to give proper exposure.The ISO is used to determine shutter speed and aperature settings.
Shutter speed is a measure of how long the shutter is open. It is measured in fractions of a second. Aperature is a measure of how large the opening is in the shutter. You read it as f stop. The larger the number, the smaller the opening.
Together f stop and shutter speed are set to get the correct amount of light. A number of f-stop shutter speed combinations are possible. The combination you choose would be determined by the need to stop movement or not, and the depth of field needed (how much you need focused clearly)
What%26#039;s the difference between ISO, shutter speed, and aperture?
ISO refers to how sensitive the film or digital camera is to light.
Shutter speed refers to how long the film or sensor is exposed to the image.
Aperture refers to the optical setting that allows the lens area to be reduced to control the intensity of the light striking the film or sensor.
Any time one is changed changing either of the other 2 could be used to compensate. When a combination of the 3 is appropriate for the lighting of the subject that is called proper exposure.
Reply:You have it quite wrong. ISO is a measure of the film%26#039;s (or CCD%26#039;s) light sensitivity. Think of it as a measure of how many photons must land on the film/sensor to form an image.
Shutter speed is just that, a measure of how long the shutter is open in front of the film/ccd. This is a sort of valve that only allows so many photons of light through the lens.
Aperture is a kind of measure of how large the %26quot;valve%26quot; is that lets the photons through the shutter. A small valve (high aperture f number) will restrict the flow of photons requiring a longer shutter duration to allow enough photons to reach the film/ccd to form an image.
Normally one would want to use as large an aperture as possible to achieve the shortest exposure time. This leads to problems though due to the optical properties of lenses. large aperture lenses (low f number) have a small depth of focus, that is, only a short distance in front of the lens is actually in focus. If you want all of the scene to be in focus, one normally chooses a high aperture number, thus requiring a longer exposure or a switch to a faster (higher ISO) film or ccd sensor.
Astrobuf
Reply:Well let me see if I can help explain this to you.
ISO: Is a measurement of the sensitivity to light of the film or sensor. The higher the number the more sensitive to light the film or sensor is. The downside is that you will get more noise or grain the higher the ISO you use.
Shutter Speed: The shutter speed is how fast the shutter of the camera opens and closes. The slower the shutter speed the more light is allowed in to expose the film or sensor. If you want to freeze action you need a fast shutter speed of around 1/250th of a second or faster.
Aperture: The aperture is in the lens. There is a diaphram in the lens that opens up wide or closes down to a very small hole. Much like the Iris in your eye. The aperture does two things.
1. It controls the amount of light that passes through the lens to the film or sensor. The larger the aperture on your lens the faster the shutter speed you can use. This is especially useful in low light situations.
2. It controls the depth of field. Depth of field is the amount of the photograph that is in clear focus. For portraits or macro shots you generally will have a very shallow DOF. Where the person is in focus and the background is blurred. For a landscape you want the opposite. You want the entire photograph in focus. To control the DOF you adjust the aperture. Large aperture (small number) like F1.4 or 2.8 will give you a shallow depth of field. The larger the number the deeper your depth of field.
I hope this helps.
Reply:In digital cameras, ISO is the sensitivity of the camera to light. A higher ISO means you need less light to get a proper exposure, however that may come with a cost in quality, depending on the camera.
The shutter opens and closes when you take a picture. The quicker it opens and closes, the less light passes through the lens. A quick shutter speed, like 1/500 of a second, allows a tiny amount of light in. A slow shutter speed, like 1/30, allows a relatively large amount of light.
The size of the opening in the shutter is the aperture. Small apertures (think of them as small holes, though that is it how it used to be, not how it is now) let in a little light. A small aperture would be say F16. Large apertures allow a lot of light in. A large aperture would be F2.8.
All three of these affect the exposure. If you set you camera to ISO 100 and aperture priority, you notice as you increase the aperture (which means the hole is smaller so less light comes in), the shutter speed gets slower, which means that more light is coming in. Increasing the aperture by one stop decrease the shutter speed by one stop.
You can see then how these two are directly related. Every stop is doubling or halving the amount of light. If half as much light is coming due to a one stop change in Aperture, twice as much light needs to come in due to a slower shutter speed in order maintain the same exposure.
I know that is a lot and confusing. Try this link in wikipedia that talks about exposure
http://en.wikipedia.org/wiki/Exposure_%2...
Reply:After all the technical explanations by the others which some of them are good, let me explain more in layman%26#039;s term.
ISO, shutter speed, and aperture all has to do on how much you are letting the light in to expose a film or sensor.
ISO - the brighter the environment the lower the number
ISO of 200 in a bright sunny day or even 100. 400 when it get a little bit darker around dawn or higher at night. For fast images like sports you can use 400 or higher to help freeze the images. However, the higher the ISO 400 and up the grainier it gets or in digital term it%26#039;s called %26quot;noise%26quot; not the sound but the look. Here%26#039;s a site to explain it more and samples:
http://www.cameratown.com/guides/iso.cfm
Shutter speed - refer how fast or slower the shutter open and close to let lights in the camera. Ideally 125 or higher is good for freezing images or even %26quot;prevent%26quot; blurs from shaky hands. Here%26#039;s a website for more explanation and sample:
http://www.ephotozine.com/article/Camera...
http://www.mir.com.my/rb/photography/fot...
Aperture: if the opening of your lens inside - like the iris of our eyes, it gets smaller when it%26#039;s brighter and bigger when it%26#039;s darker, same principle. Aperture also will determine your Depth of Field - how blurry or clearly your background could be. Here%26#039;s a site about aperture:
http://www.mir.com.my/rb/photography/fot...
Reply:http://www.fredparker.com/ultexp1.htm
Heres a good website.
As stated by others the ISO is the sensitivity of the film. The numbers, if you%26#039;ll notice, will double and halve from the previous number (50, 100, 200, 400, 800, 1600, 3200, etc...). When you halve or double the ISO you move one full stop (see my link for a more consice explination).
Shutter speeds are obviuosly the speed that the shutter opens and closes. You will see that a full stop will be either double or half of its previous stop. The link I gave only deals in full stops but many cameras will let you select half or third stops (seemingly only to confuse someone who%26#039;s just trying to figure this stuff out).
Now aperture is a little different. It doesnt jump by doubling the number. It has its own scale. It would be good for a beginner to learn the apertures. f/1.4, 2.0, 2.8, 4.0, 5.6, 8.0, 11, 16, 22, 32. Once you learn them you can use them. When refrencing lenses some will call a lens a %26quot;fast%26quot; lens. This has nothing to do with how fast the lens reacts to the camera, its more about how fast the lens lets the camera shoot. A f/2.8 lens is considered fast, anything with a lower number is faster, anything with a larger number is slower. Lenses that state that they go from one number to another mean that at the wide end of the zoom they are this fast, and at the tele end of the zoom they are this fast (a stop or so %26quot;slower%26quot;).
With the advent of the digital camera you can now more actively control the ISO. With film you had to change the roll and that wasnt convenient, now you just push a few buttons.
Reply:ISO is a measurement of the sensitivity to light of a light sensitive surface, whether film or digital sensor. The lower the number the less sensitive; the higher the number the more sensitive.
Inside the lens there is a diaphragm which is made up of thin movable blades which can be opened or closed to form the aperture or f-stop. The smaller the number the bigger the opening. So f1.2 would be very large and f22 would be very small. The aperture controls how much light is admitted so f1.2 would admitt all the available light and f22 would admit very little.
The shutter speed controls how long the light is allowed to expose the light sensitive surface. It is controlled by both the ISO used and the f-stop chosen. The shutter speed also has a role in stopping action. The faster the shutter speed the more likely that a runner or moving car will be %26quot;frozen%26quot; with no apparent blur.
Here is a hypothetical example to show the ISO-aperture-shutter speed relationship. For our purposes we%26#039;ll be shooting on a clear, sunny day*.
ISO 100
f2 @ 1/8000
f2.8 @ 1/4000
f4 @ 1/2000
f5.6 @ 1/1000
f8 @ 1/500
f11 @ 1/250
f16 @ 1/125
ISO 200
f2 @ 1/16000
f2.8 @ 1/8000
f4 @ 1/4000
f5.6 @ 1/2000
f8 @ 1/1000
f11 @ 1/500
f16 @ 1/250
As you can easily see, our shutter speed decreases as less light is admitted by the smaller f-stops. f2.8 admits 1/2 as much light as f2; f4 admits 1/2 as much light as f2.8, etc. Since less light is admitted our shutter has to stay open longer to allow the light to expose our film or sensor.
* This example is based on the time-honored %26quot;Sunny 16 Rule%26quot; which states: %26quot;On a sunny day, set your f-stop to f16 and your shutter speed to 1/ISO.%26quot; So if you%26#039;re using ISO 100 your shutter speed at f16 is 1/125. It was created back when shutters were mechanical. Today%26#039;s electronically controlled shutters are, in effect, %26quot;stepless%26quot; and can actually achieve a shutter speed of 1/100 or 1/200 when needed.
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