#High f stop how to#
Next, we learn how to numerically describe aperture diameter using the term f-stop. In this analogy, the iris is the diaphragm composed of aperture blades, the pupil is the aperture, and the retina is the image sensor.
This is essentially the same way a camera records an image. The retina then converts the light it has received into neural signals that ultimately allow the brain to construct an image - the image being what the eye is looking at. When light passes through the pupil, it hits the retina at the back of the eye. The iris of a healthy eye automatically controls the amount of light passing through the pupil by widening and narrowing the diameter of the pupil. In the center of the iris (the colored part of an eye) lies the pupil, which is the small black hole in the eye that allows light to enter. By adjusting the aperture size, the photographer can control the amount of light hitting the camera sensor, and ultimately the exposure of an image.Ī classic analogy that is often used to explain aperture is the iris and the pupil of the eye. The amount of light entering the lens decreases as the aperture diameter is reduced. Technically we may even be better at making tiny apertures than huge fast lenses there is just no practical need for them.Figure 3. There may be some desire for motion blur (slow shutter speed, small aperture setting) but any kind of extra reduction can be compensated for with an ND filter. Practically speaking, ambient sunlight never really gets bright enough to warrant some extremely small F/Stop for a somewhat "standard" exposure.
On a similar note, generally speaking, photographers have always wanted faster lenses to allow the use of higher shutter speeds (and possibly slower film/ISO speeds) in low light. Thus a quite sizable front element is needed for say an F/1.2 50mm lens while an F/45 500mm lens can be achieved with a relatively easy to machine hole size and modest diameter front element.Īlso for the record, that Zeiss F/0.33 lens never actually worked. Keep in mind that since F-Stop is calculated in comparison to the front (entrance) element as well as the focal length. The Cooke PS945 can stop down to a whopping F/90 and appears to still be in production.
With that in mind a lot of their more modern H-System lenses have similar specs. However all of these lenses are currently out of production. The 350mm Tele-Tessar, 250mm Sonnor, 120mm and 135mm S-Planar could also be stopped to F/45. The Hasselblad 500mm Appo-Tesar made for the V system could be stopped to f/45 (and is the smallest aperture in my collection and the smallest I have come across). That depends if by production you mean in production now, or has been in production in the past and I will generally reference lenses for typical photography applications.
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