Aperture & Shutter Speed


APERTURE
A space through which light passes in an optical or photographic instrument,
especially the variable in which light enters a camera.

SHUTTER SPEED
Is the length of time a camera’s shutter is open for, when taking a photograph,
the amount of light that reaches the cameras is proportional to the exposure time.


Photography is all about light, light controls what you see in a photograph, because natural light changes constantly we need to be able to control this, and use this to our advantage.

Aperture
In photography the aperture is the opening behind the camera’s lens that permittes varied light through, depending on the adjustments made by the photographer. The aperture uses these things called aperture blades also known as f-stops to limit the light passing through. The light permitted by these blades is measured within the focal ratio, more commonly known to photographers as f-numbers.

Focal Ratio
This is the measurement between the size of the lens of a camera in relation to the diameter of the opening between the apertures f-stops. These measurements are used for the adjustments of the aperture, allowing a photographer to identify how wide the aperture is to how small the aperture is. Most modern cameras use a one-third f-stop type aperture range, bellow is the f-numbers that most modern cameras range from…

f/1.0, f/1.1, f/1.2, f/1.4, f/1.6, f/1.8, (f/2.0 Large Aperture) f/202, f/2.5, f/2.8, f/3.2, f/3.5, f/4.0, f/4.5, f/5.0, f/5.6, f/6.3, f/7.1, (f/8.0 Medium Aperture), f/9.0, f/10.0, f/11.0, f/13.0, f/14.0, f/16.0, f/18.0, f/20.0, (f/22.0 Small Aperture)

As the numbers go up the smaller the diameter of the aperture gets, the smaller the amount of light is permitted through. And as the numbers go down the larger the diameter of the aperture gets, allowing a larger amount of light through. Here is a diagram that shows exactly what I am talking about.

aperture2(f/2.0) Wide apertures reduce the depth of field and blur the background, this allows the photographer to focus on the subject you are taking the photograph of. A wide aperture would need a faster shutter speed to freeze the action.

wideaperture

(f/22.0) Small apertures increase the depth of field and allow for great land scape shots, smaller apertures allow for a slower shutter speed, this allows for creative motion blurs and really nice light trails on a night-time.
small



Image Sensor & ISO

The image sensor is a tool located to the back of the camera, this sensor captures the optical images using the light permitted through from the aperture and then converts them into digital images. Image sensors are sensitive to light, the sensitivity of an image sensor is measured by ISO.

ISO is measured in numbers that double depending on the sensitivity of the image sensor, the lower the number the lower the sensitivity, the higher the higher the sensitivity, this can be adjusted on a camera. As the ISO measurement goes up the previous number doubles, but the same happens with the sensitivity. Most cameras has a set base ISO Nikon: 200 ISO, and some cannons: 100 ISO. Below is scale showing how the ISO goes up,

100 – 200 – 400 – 800 – 1600 – 3200 – 6400 ect…

Higher ISO settings are generally used for darker optical images, you are able to take a photograph without using the flash in the dark, the only problem is that there will be grain/noise in the digital image, so the lower the ISO the finer the grain in the image will be. It’s always best to just use the set base ISO when taking pictures. As the ISO goes up, so does the sensitivity, this means it takes less time to take an image.

iso

below is a scale I came across online that shows exactly that.
ISO Speed Example:
ISO 100 – 1 second
ISO 200 – 1/2 of a second
ISO 400 – 1/4 of a second
ISO 800 – 1/8 of a second
ISO 1600 – 1/16 of a second
ISO 3200 – 1/32 of a second

Say your camera needed 1 second to capture a photograph at ISO 100, by switching the ISO up to 800 you could take that image in 125 milliseconds.


Shutter Speed
Is the speed in which the shutter of a camera opens and closes, it is the control of light permitted to the image sensor at that moment. The speed can be adjusted, the slower the shutter speed the more light is permitted through at that time creating a more blurred image, down to prolonged light exposure to the image sensor. A faster shutter speed creates a sharper still image, because it’s a lot faster it captures a limited amount of light at that time, the photograph was quickly snapped. As you can see from the photograph below, the photo on the left is a slower shutter speed and the photo on the right is a faster shutter speed.
shutterShutter speed is measured within fractions of a second, so fast shutter speed would be 1/500th of a second, and a slower shutter speed would be 1/60th of a second.


References:
http://digital-photography-school.com/iso-settings/
http://www.steves-digicams.com/knowledge-center/how-tos/digital-camera-operation/how-is-shutter-speed-measured.html
http://www.digitalcameraworld.com/2012/05/16/apertures-photography-cheat-sheet-when-to-go-small-and-when-to-go-wide/
http://en.wikipedia.org/wiki/Aperture
https://photographylife.com/what-is-aperture-in-photography

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