Apertures in cameras vs confocal microscopes
Question:
In a normal confocal microscope, a pinhole is used to get the image of only a thin slice through the specimen, eliminating light from all points which are not in focus.
In a normal camera, a small aperture is used to get a large depth of field, with a sharp imaging of objects both close and far away from the camera.
Why does a small hole give rise to these apparently opposite effects?
Answer (I think):
In a confocal microscope, the pinhole is in the focal plane, and the light reaching the sensor is actually "out of focus", whereas in a camera, the film (or digital sensor) is in the focal plane, while the aperture is in front of the focal plane.
Comments?
In a normal confocal microscope, a pinhole is used to get the image of only a thin slice through the specimen, eliminating light from all points which are not in focus.
In a normal camera, a small aperture is used to get a large depth of field, with a sharp imaging of objects both close and far away from the camera.
Why does a small hole give rise to these apparently opposite effects?
Answer (I think):
In a confocal microscope, the pinhole is in the focal plane, and the light reaching the sensor is actually "out of focus", whereas in a camera, the film (or digital sensor) is in the focal plane, while the aperture is in front of the focal plane.
Comments?
1 Comments:
I think you can actually view the planes at which the aperture is as oppisite. In a camera it is at an 'infinite' distance from the focus. This can be accomplished by lenses and has the opposite effect of placing an aperture in the focal plan as is the case in the confocaal microscope.
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