Explain aperture to me please?

Madweasel wrote in post #9061133
I know I'm late to the discussion, but one way to think of the reason for 'faster' lenses (e.g. f/1.4 over f/1.8 ) costing much more is to draw an analogy with fast cars. Why does one that can do 180mph cost so much more than one that can do 120mph, when most of the time you're only going 50mph? That higher performance costs: in the case of lenses there is more glass in the faster lens, there are stonger aberrations to overcome in design, and manufacturing tolerances are going to be tighter. A good example is to look at the prices of the 3 current non-macro 50mm EF lenses; f/1.8, f/1.4, and f/1.2. They go up geometrically, even though the differences in speed are comparatively small (one stop covers the whole range).

hard12find wrote in post #9041057
The aperture is located only in the lens, the camera controls it electronically in the newer digital camera's. Aperture is one of four things used in combination with one another to control how much light reaches the sensor. The 4 things are as follows in no particular order;
1. ISO - This setting controls how sensitive the sensor is to light with lower numbers being less sensitive and upper numbers being more sensitive. So in bright daylight you would use lower number ISO settings Like 100-200, where as if you are shooting in a dark room and dont want to use flash, then you would want to set higher ISO settings like 400, 600, up to and in excess of 6400 on some cameras.

Shutter speed- the shutter is like a window shade that covers the sensor so no light gets to it, until you press the shutter release. Shutter speeds control how long the window shade stays open. Shutter speed also controls how you view objects that are in motion relative to the camera. A fast shutter speed will "freeze" motion, so if you shoot a spinning airplane propeller with a fast shutter speed it might look funny because it looks like it is standing still. and conversely a slow shutter speed is good to convey motion, I'm sure you have seen waterfall or stream photos where the water looks creamy and flowing...that is due to a slow shutter speed, leaving the shutter open for a longer time to capture the movement of the water.
Aperture- aperture is basically the size of window you are allowing the light to flow through, inaperture it is important to remember that the smaller numbers F1.4 are a larger window than the bigger numbers like F22 being a small window. Aperture controls how much depth of the picture is in crisp focus. (depth of focus) A large aperture opening will have a small area that is in focus and most of the foreground and background will be out of focus (callled Bokeh). A large aperture has the advantage of allowing more light to fall on the sensor in a shorter time so in low light situations, you can get faster shutter speeds allowing you to get better photos handheld without blur. Conversely if you are shooting a portrait of someone with a distant mountain in the background and you want the subject and the mountain to be in crisp focus then you will want to set a smaller aperture such as F22, but will get a better photograph if you are on a tripod because the shutter will have to stay open longer to allow the same amount of light to fall on the sensor.
4. added light- self explanitory . auxillary light can work with the other three settings to change ISO needed, Shutter speed needed or aperture needed for any particular exposure.

If you really want to get a handle on exposure I would reccomend reading as much as you can on the subject. Many folks on here reccomend Bryan Peterson's understanding exposure, and I know John Hedgecoe has a few good beginners books.

Rekd wrote in post #9061279
First of all, please move over to the right lane if you're going to do 50 all the damn time. :twak:

Roy Mathers wrote in post #9061506
He comes from the UK, so you wouldn't really want him in the right lane!

Roy Mathers wrote in post #9061506
He comes from the UK, so you wouldn't really want him in the right lane!

Rekd wrote in post #9061279
...the comparison would be more accurate using a car that does 180 vs a car that only does 170. Those cars are high performance and at that level of performance, every extra mile per hour costs considerably more than the one before. Many cars can do 120, so your comparison would reflect an f1.4 lens vs a 2.4, not a 1.8. And if you want to do 180 and not spend the money for a Z06 Vette, why not just spend 1/6th the cost and buy a busa that will do more than 180??

Madweasel wrote in post #9062492
You're saying my analogy was not so helpful after all. I only picked the numbers out of my **** - I'm sure you knew what I was getting at.