Aperture and Sensor size question.

[Serithin]

I have a question that might be for beginners. I have Googled but found no answers. The question is.. I assume that the image coming through the lens fills the size of the sensor. Under this assumption. How does the image coming through the lens fill the sensor's physical size if the aperture opening is smaller then the sensor? Is the image being magnified by optics once it passes the aperture opening? To simplify my question I'll ask this, If your f-stop is at f.22 for example, How is the processed image not a small dot or larger dot depending on the size of the opening on the lens? Thanks.

 

[Ysarex]

Think of a projector in an auditorium that is projecting an image onto a large 15 foot wide screen. Consider the size of the projection lens -- 15 foot?. Why isn't a small circle an inch or so projected to the screen? Now just flip that process to the inside of a camera.

Joe

 

[480sparky]

When you look through a lens with the aperture closed, you're looking through a small hole. However, you're looking at it with a 'sensor' the size of your eye's pupil. Now "tumble" the lens in your hand like a slowly-turning childs' top, and you're still looking through the same size hole, no?

So in effect, you're looking through the lens as it transmits light across a much larger area than your eye covers. This is what the sensor sees..... each pixel is looking through the same size hole, but at a different angle through the lens.

 

[Serithin]

So the image shrinks inside the lens then projects back out before it hits the sensor?

 

[Serithin]

Ysarex said think of a projector. A projector has optics that magnify the image, So is that a yes that the image is magnified onto the sensor? Otherwise what is causing the image to project out to fill the sensor?

 

[Serithin]

http://www.rags-int-inc.com/PhotoTechStuff/Lens101/LensDiagram_1024.gif

 

[Serithin]

After hours of searching I found a simple illustration.