I understand that Aperture impacts how much light hits the sensor and depth of field, and I take this into consideration when planning pictures, but I don't really understand how making the aperture hole smaller can let less light hit the sensor without impacting how much of the image is on the sensor. If when the hole closed down less of the image was on the sensor, like a black circle around it, then I would understand, but how it can have the same size of image hit the sensor, but with less overall brightness with a smaller hole just doesn't compute in my mind, but I know it must be true.
Anyone have any sites that explains this part of aperture?
aperture works in the same way our eyes work when it is dark we need more light to see so our pupils widen when it is bright we need less light to see so our pupils get smaller, the size of the pupil does not effect the size of the image we see, we do not have a dark vignette around what we see in bright light. and the same is true in the camera aperture it is just there to widen the area that light can be captured and has very little to do with the size of the image captured that is all taken care of by the lens
the eye is definitely much more complex than an aperture but it works in pretty much the same way where photographs do differ from the eye is not one of image size but of image clarity, when the aperture is small the angle of refraction is shortened so you get a clearer image as light is focused on the sensor but when the aperture is wide onen the angle of refaction is lengthened and the background becomes fuzzy this is the depth of field
this may shed a bit of light on things as I am not really great at trying to explain http://www.cambridgeincolour.com/tutorials/depth-of-field.htm
narrowing the eyelids (squinting) gives us a greater depth of field just as raising the aperture does. I still think our images should be circles instead on rectangles (remember the feeling of getting that widescreen television? you felt like you've been missing half the movies.
It's because all the rays of light coming from all edges of the environment converge on our eyes at (pretty much) a single point, so it lands on the retina - our lens (and cornea) are responsible for bending the light and making the rays converge.
It's the same with the camera - the lens has curved glass, which grabs all the light rays from the environment and bends them so that they all converge on the sensor.
And, to add to that, it doesn't matter how wide or narrow the hole (pupil or aperture) is, because the light is converged at the point where it passes through!
@mallocarray The diaphragm, which opens and closes to create the aperture, is close enough to the lens that it does not block any part of the film or sensor.
The illustration below might help.
It is a rather simple diagram, but I hope it helps.
Side note: Though the DOF continues to increase the smaller the opening, the quality of the shot may degrade. For many lenses, the sharpest image comes about f8 or f11.
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this may shed a bit of light on things as I am not really great at trying to explain
http://www.cambridgeincolour.com/tutorials/depth-of-field.htm
It's the same with the camera - the lens has curved glass, which grabs all the light rays from the environment and bends them so that they all converge on the sensor.
The lens sits just behind the iris of your eye :)
The illustration below might help.
It is a rather simple diagram, but I hope it helps.
Side note: Though the DOF continues to increase the smaller the opening, the quality of the shot may degrade. For many lenses, the sharpest image comes about f8 or f11.