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A varifocal lens is a non-fixed focal length lens where the focus changes with focal length. This is in contrast to true zoom lenses, which retain correct focus throughout their focal length range. True zooms have a constant maximum aperture at all focal lengths (as in a 28-70mm f/2.8 lens), while varifocals have maximum apertures that increase (in number, but decrease is size!) as the focal length increases (as in a 28-70mm f/3.5-5.6 lens, which has a maximum aperture of f/3.5 at 28mm, that becomes smaller in size as the focal length increases until it reaches a value of f/5.6 at 70mm).
Varifocals are easier to design and build than true zooms which explains their ubiquity in the camera market. Note that they are commonly, but erroneously, referred to as zoom lenses by users and manufacturers alike.
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What are progressive glasses?
Ones with varifocal lenses.
What kind of CCTV camera is used in banks?
used varifocal box cameras.this for better in banks
When was zoom first invented for cameras?
For cameras, about 1902. Production of the patent from that year did not take place until about 1932 and was used in 35mm movie cameras as the first true zoom (meaning the focal plane did not shift appreciably when the lens was zoomed). The concept was first invented for telescopes around 1834, but it was a varifocal lens, in that it did not maintain focus when zoomed).
What are some nine letter words with 1st letter V and 5th letter F and 7th letter C?
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 2 words with the pattern V---F-C--. That is, nine letter words with 1st letter V and 5th letter F and 7th letter C. In alphabetical order, they are: varifocal venefical
What are some nine letter words with 4th letter I and 5th letter F and 6th letter O?
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 8 words with the pattern ---IFO---. That is, nine letter words with 4th letter I and 5th letter F and 6th letter O. In alphabetical order, they are: califonts coliforms cuniforms latifondi manifolds pisiforms unciforms varifocal
What are the advantages and disadvantages of a three dimensional monitor using a varifocal mirror with a stereoscopic system?
A three dimensional display utilizes a varifocal vibrating mirror which reflects the screen on a CRT. The varifocal mirror is vibrated at a rate synchronous with creation of frames on the point plotting CRT. A video source is utilized of the type having red, green and blue outputs utilized for normally creating color display. However, the coding is such that what would normally be interpreted as red, green and blue outputs of the video source are instead interpreted as x position, y position and intensity information for a CRT accepting x, y and i signals. A depth or z coordinate is implicitly encoded in the video source at the position within a single frame of the video source where the corresponding (x, y and i) values are stored. This position can be the relative position on a magnetic or optical disc, or position around a magnetic drum. In one embodiment of the invention a raster graphics system utilizing a frame buffer is utilized. The frame buffer is divided into buckets, and the particular bucket within the frame buffer where an (x, y, i) display point is stored corresponds to the z value or depth coordinate of that point. Techniques are disclosed for interactive modification of three dimensional displays utilizing the look-up tables and registers in a standard raster graphics display system for achieving image rotation, transformation, scaling, spatial windowing, intensity windowing, cursor control, cursor inking, and blinking.
What are some nine letter words with 3rd letter R and 4th letter I and 7th letter C?
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 13 words with the pattern --RI--C--. That is, nine letter words with 3rd letter R and 4th letter I and 7th letter C. In alphabetical order, they are: abricocks acritical apricocks juridical mirifical pericycle pyritical soritical thridaces variances varifocal veridical virilocal
What are some nine letter words with 3rd letter R and 6th letter O and 8th letter A and 9th letter L?
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 10 words with the pattern --R--O-AL. That is, nine letter words with 3rd letter R and 6th letter O and 8th letter A and 9th letter L. In alphabetical order, they are: acrosomal baritonal horizonal paradoxal pericopal pyridoxal torsional varifocal versional virilocal
What's the difference between a varifocal lens and a zoom lens?
A telephoto lens is a camera lens that is typically used for taking photographs of subjects that are a distance away such as a landscape. They are also used for subjects that the photographer can not get close to such as wildlife, and sporting events. A zoom lens allows the photographer to get very close to the subject matter and then zoom in.
What are some nine letter words with 1st letter V and 2nd letter A and 3rd letter R?
According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 36 words with the pattern VAR------. That is, nine letter words with 1st letter V and 2nd letter A and 3rd letter R. In alphabetical order, they are: varactors varguenos variables variances variating variation variative varicella varicosed varicoses varicosis variegate varietals varieties varifocal variolate variolite varioloid variolous variorums variously variscite varisized varistors varityped varitypes varletess varlettos varnished varnisher varnishes varooming varsities vartabeds varvelled varyingly
Can you buy new eyeglass frames to fit old lenses?
Yes but only if the frame is in quite good condition. If the frame is weak or has been damaged, it may not be able to take the stress of having new lenses fitted. It also depends on the lens type. For example, you might not be able to have a pair of reading glasses fitted with varifocal lenses. If your precription has changed dramatically or the frame previously belonged to someone with a different prescription to yours, you may also have difficuties fitting new lenses. You Optometrist will be able to advise you further. It is impossible to give a definitive answer without knowing your precription and seeing the frame.
CCTV stands for what?
CCTV (closed-circuit television) is to monitored, primarily for surveillance and security purposes. CCTV depends on strategic placement of cameras, and observation of the camera's input on monitors somewhere. as a result of the cameras communicate with monitors and/or video recorders across non-public cable runs or wireless communication links, they gain the designation "closed-circuit" to point that access to their content is proscribed purposely solely to those able to see it. There are different types of CCTV Cameras • Dome Camera • C-mount Camera • Bullet camera • PTZ Camera • Day/ Night Camera • Thermal image camera • Network Camera • Varifocal Camera • HD Cameras
