So, why should you care about the pupils? For me, I don't really need to know the exact position
or size of the pupils, but I do find it useful to understand that the pupils are where the work of the
aperture is accomplished.
Entrance pupil determines:
F-stops/f-number of the lens
Image exposure
Depth of field
Object resolution (how small of object the camera can image)
Center of perspective of the lens - useful for panoramic photography
Exit pupil determines:
Depth of field
Image resolution (how many sharp pixels on the image)
Image exposure
These subjects will be addressed in later sections.
or size of the pupils, but I do find it useful to understand that the pupils are where the work of the
aperture is accomplished.
Entrance pupil determines:
F-stops/f-number of the lens
Image exposure
Depth of field
Object resolution (how small of object the camera can image)
Center of perspective of the lens - useful for panoramic photography
Exit pupil determines:
Depth of field
Image resolution (how many sharp pixels on the image)
Image exposure
These subjects will be addressed in later sections.
The entrance and exit pupils of a lens are a tough subject matter to comprehend. The subject is
even harder to find good simple written discussions on. To start: What are the pupils? To put it
as simply as possible, the pupils are the apparent size and position of the aperture of the lens
when viewed from the front or the back.
When you look at the aperture of the lens from the front or the back of the lens you are seeing
the aperture by way of the intervening lenses. Those lenses will tend to change the size and
position of the aperture in relation to its real position in space. The entrance pupil is the aperture
when viewed through the front of the lens and the exit pupil is the aperture when viewed through
the back of the lens. The entrance and exit pupils can be wildly different from each other in size
and position depending upon the lens construction.
even harder to find good simple written discussions on. To start: What are the pupils? To put it
as simply as possible, the pupils are the apparent size and position of the aperture of the lens
when viewed from the front or the back.
When you look at the aperture of the lens from the front or the back of the lens you are seeing
the aperture by way of the intervening lenses. Those lenses will tend to change the size and
position of the aperture in relation to its real position in space. The entrance pupil is the aperture
when viewed through the front of the lens and the exit pupil is the aperture when viewed through
the back of the lens. The entrance and exit pupils can be wildly different from each other in size
and position depending upon the lens construction.
| The Pupils - an Introduction |