# Tag Info

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Angular Field and Angle of View Lens makers use the term “angular field”, which is the angle as measured from the center (axis) of the lens. Thus, a lens with an angular field of 20° to the photographer will be an angle of view of 40°. TV sets are sold by their corner-to-corner (diagonal) measure because this is the largest dimension of the rectangular ...

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Then why aperture for APS-C has to be 25mm? Because the f-number is a measure of focal length divided by the diameter of the entrance pupil. That is, the focal length of the lens divided by how wide the aperture looks when viewed from the subject's position in front of the lens. But its a fact APS-C lenses are cheaper than FF lenses, so they must have less ...

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The lens' angle of view (AoV) is the same regardless of what camera it is on. The system's AoV is the combination of the lens' AoV and the sensor's AoV. "If we talking about manual focus lens from FF camera i can use it on APS-C camera then i will get different field of view so about 33% of outer side of the lens will not be used?" That part is ...

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The difference in angle of view is due to the smaller image sensor size, not the lens or it's aperture. APS-C lenses can be made cheaper and smaller because their image circle only has to cover the smaller image sensor on APS-C cameras.

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The block diagram for your lens appears to be a variation of the Zeiss Tessar design created by Dr. Ralph Rudolph. Roger Cicala, in one of his excellent blog entries at lensrentals.com says: Literally dozens of today’s excellent lenses are simply modifications of the Tessar: Leitz Elmars, Zeiss Sonnars, Kodak Ektars, Schneider Xenars, Voigltander ...

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The only way to get your lens to focus to infinity, is to move the lens further from the film/sensor plane, to where it was designed to be. I assume it can be made to focus if i change distance between lens elements? What elements i need to space out to restore focus ability, can correct spacing be figured out mathematically? What is the basis of your ...

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Why using 50mm lens on FF gives more DOF than using 50mm lens on APS-C? As others have already answered in greater depth, because the magnification ratio from the two sensors is different if we want to view both images at the same display size. Some blur that is just barely small enough to still look like sharp points to our eyes when magnified less can be ...

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Lens designs, even in the olden days, are highly optimized for sharpness and several kinds of optical aberrations. Even small changes, including distance between elements, are bound to degrade image quality. So, usually, you don't want to tamper with the existing design. Instead you add lenses, either in front (fish eye lens) or between lens and camera (...

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This is exactly what a telecompressor/focal reducer/"speed booster" is for. It can be bought as a ready made unit with a choice of mirrorless camera mounts on one side and a choice of SLR/DSLR mounts on the other. Since these devices are more expensive than normal adapters, it can be worth buying strategically in case you have multiple legacy ...

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Introduction The depth of field on a digital camera is a delicate subject because there are two different approaches. The first, which has no equivalent in the field of analog photography, corresponds to the best possible image taking into account the characteristics of the sensor, i.e. the optical image on a sensor of a point in the scene must be smaller ...

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It is due to magnification/enlargement... a smaller sensor/negative requires more magnification/enlargement in order to create the same sized output image; so a point of blur will be enlarged more and therefore be more apparent (less DoF). I.e. a 36mm wide FF sensor has to enlarged ~7x to make a 10" wide print, whereas a 24mm wide APS sensor has to be ...

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It has to do with the circle of confusion, that is, a spot of light that looks acceptably sharp. Smaller sensors have a correspondingly smaller circle of confusion for an acceptably sharp image which is why the DOF is different between full-frame and APS-C sized sensors. DOF ≈ 2u²Nc/f² Where u is the distance, N is the f-number, c is the circle of confusion, ...

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Focal reducers convert both the focal length and aperture of the lens. You can think of it as multiplying by 1 = 0.7/0.7. Your 50/2 lens will behave like a 35/1.4 (= 50×0.7 / 2×0.7) lens when used with the focal reducer. Although DOF and background blur tend to be inversely related (minimizing DOF will maximize background blur), they are different concepts. ...

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The combined lens (50mm f/2 and a 0.71x speedbooster/telecompressor) will act like a 35mm/f1.4 lens in all regards (Same applies to teleconverters, in the other direction. lens designs exist that consist of a teleconverter or telecompressor behind a main lens, eg many 100mm macro lenses are 50mm macro lenses with a teleconverter in the back...). DOF will be ...

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We measure the potential “speed” of a camera lens using the f-number system. The f-number is derived by dividing the focal length of the lens by the working diameter of the lens aperture (iris). As an example, a 50mm focal length lens with its aperture set to 25mm is operating at f/2. If we wish this lens was faster, we can mount a “speed buster”. What ...

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