aperture and shutter formula

Started Dec 26, 2010 | Discussions thread
mothman13
Contributing MemberPosts: 925Gear list
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Re: aperture and shutter formula
In reply to adichik, Dec 26, 2010

adichik wrote:

hi..
i'm beginner for using new dslr Nikon D3100
it's awesome when i'm using it..
so..i want to ask..

can you give me some formula for shutter and aperture
when i capture landscape what shutter and aperture can i use it..

or when i capture some potrait with someone run behind it what shutter and aperture can i use..

thanks....

Greetings adichik, and welcome to the wonderful world of photography!

Each exposure depends upon three components: shutter speed, aperture and iso setting.

The shutter speed is how long you allow light to hit the camera sensor during the shot. Aperture is the size of the opening within the lens through which light passes on its way to the sensor. ISO setting is how much the circuitry inside the camera amplifies the signal from the sensor.

Shutter speed:

Normally, this is in fractions of a second, like 1/125, 1/500 and 1/4000. Frequently, we refer to the shutter speed by using only the denominator number, 125, 500 and 4000. Just understand that because we are referring to the value in the denominator, the larger the number, the smaller the amount of time. Remember, 1/4000 is much smaller than 1/125 so if we said the shutter speed was 4000, this is a much smaller amount of time than 125. Bigger number, smaller amount of time.

Aperture:

The size of the opening in the lens through which light will pass is controlled by the F/stop setting of the camera. F/stop = (focal length of lens) / (aperture). Again, notice how the "aperture" part is in the denominator, so the larger the number here, the smaller will be the resulting F/stop value. Smaller F/stop number means bigger opening. Bigger F/stop number means smaller opening.

ISO setting:

Every sensor has a "base" ISO value. This is the starting point. When light strikes the sensor, the circuitry in the camera will turn those photons into your picture file. Each time you increase the ISO setting above the base value, you are telling the circuitry to amplify the result more and more. This is like tuning in a faint radio station. When you turn up the volume, you not only amplify the signal from the station, but also the noise. Keep turning up the ISO setting and you'll amplify both the true signal from the sensor as well as the noise in the resulting picture.

Normally, for landscape photographs, you want everything to be in focus, from close to far distant objects.

But for portraits, you want to isolate the subject from the foreground and background.

You control how much of the photograph is in focus by controlling the aperture size (control the F/stop setting). The smaller the F/stop setting (and therefore the larger the aperture size) the smaller the depth of field. Small F/stop setting means small depth of field.

For landscape shots you might want to use something like F/8 to F/11 or even F/16 to get as much in focus as possible. For portrait shots, you might want to use near the smallest F/stop setting as your lens is capable of giving. You'll usually get the sharpest results by decreasing the minimum F/stop setting just a bit ..

I have a few beginner tutorials at my website you might want to take a look at, like the one for exposure:

http://www.texasmothman.com/tutorials/exposure.asp

See the rest listed on the main page:

http://www.texasmothman.com

Good luck!

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