Click on the 'For Gary!' title to go to an indepth view on the subject and more at Luminous Landsape.
Gary - PLEASE COMMENT ON CONTENT AND OR QUESTIONS AND I WILL ATTEMPT TO ANSWER THANKS.
All Lenses you place on your camera have the ability to change their aperture size. Or the hole that lets the light in.
The more light allowed in through the lens that is allowed to reach the sensor (the part of the camera that captures the image) then the faster the shutter can operate.
Example 1
If you are hand holding your camera to take shots then you will require a fast shutter speed so as to avoid 'camera shake', (blurring). Often you require a way of being able to produce false light so as to keep the shutter speed fast...yes you guessed it....a Flash! of course a flash can be used to create lots of different effects on an image but for now thats close enough!
Lets look briefly at aperture (the hole in the lens)
when using your camera in the green square Mode (Fully auto) it will control all aspects i.e.:
shutter speed
aperture size
flash control
ISO - i'll explain later!
This is fine but you wont learn much in this mode if you choose it all the time so....
turn the dial anti-clockwise one notch and you are in 'P' mode....dont panic!
in this mode you get to set your own aperture setting and the shutter speed will compensate for you. to change the aperture number use the wheel just behind the shutter button. as you do this looking through the viewfinder you will also notice the number to the left of the aperture number you are changing also changing, this is the shutter speed reference, it is compensating for the amount of available light in the interest of keeping the exposure of the shot correct.
You also get to choose whether you want to use the flash or not.
As far as aperture is concerned, the lower the number, the bigger the hole in the lens.
So...with this in mind, what do we expect the number to be when the hole is small?....yes, correct! larger!! well done Gaz!
Now this is where it could get sticky so just trust me when i say that when the hole is small (large number) the camera can get alot more of the view in focus at once. if the hole is Large (small number) the camera only sees a small amount of the scene in true focus.
The amount of any scene that is in focus on an image is called...'Depth Of Field', or DOF.
Different types of image require different DOF. if you were to be taking a photo of a landscape and you wanted to capture as much detail in focus as you can, from the forground right in to the back, you would choose a small aperture, a larger number, maybe 20 upwards. A tripod will be useful here as the shutter speed would be slower due to the lack of light allowed in to meet the sensor.
or if you were taking a photo of a person, a portrait, you might want to blur out the background especially if the scene behind the person was cluttered or full of colour. In this senario you would choose a small number anything less than 3.5.
GARY - DON'T FORGET TO COMMENT!
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