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The 400mm f / 4 DO IS II USM, which replaced an earlier version of the same lens in 2014, [3] is one of only two Canon lenses that make use of diffractive optics (the other is the EF 70–300mm f/4.5–5.6 DO IS USM). The use of diffractive optics allows the lens to be significantly lighter than it might otherwise be.
A self-contained infinity mirror used as a wall decoration. In a classic self-contained infinity mirror, a set of light bulbs, LEDs, or other point-source lights are placed around the periphery of a fully reflective mirror, and a second, partially reflective "one-way mirror" is placed a short distance in front of it, in a parallel alignment.
A very complex dielectric mirror can reflect up to 99.999% of the light incident upon it, for a narrow range of wavelengths and angles. A simpler mirror may reflect 99.9% of the light, but may cover a broader range of wavelengths. Almost any dielectric material can act as a perfect mirror through total internal reflection. This effect only ...
The Mangin mirror was invented in 1874 [1] by a French military engineer named Colonel Alphonse Mangin as a substitute for the more difficult to manufacture parabolic reflecting mirror for use in searchlights. Since the catadioptric design eliminated most of the off-axis aberration found in parabolic mirrors, Mangin mirrors had the added ...
The mirrors are arranged in a matrix and have two states, "on" or "off" (digital). In the on state, light from the projector bulb is reflected into the lens making the pixel appear bright on the screen. In the off state, the light is directed elsewhere (usually onto a heatsink), making the pixel appear dark. Colours could be produced by various ...
Dielectric mirrors are also used to produce ultra-high reflectivity mirrors: values of 99.999% or better over a narrow range of wavelengths can be produced using special techniques. Alternatively, they can be made to reflect a broad spectrum of light, such as the entire visible range or the spectrum of the Ti-sapphire laser.
The best mirrors of this type can reflect >99.999% of the light (in a narrow range of wavelengths) which is incident on the mirror. Such mirrors are often used in lasers . In astronomy, adaptive optics is a technique to measure variable image distortions and adapt a deformable mirror accordingly on a timescale of milliseconds, to compensate for ...
The switch has two settings on most lenses: Mode 1 and Mode 2. The newest IS Mark II versions of certain EF super telephoto lenses (the 300mm f/2.8L, [6] 400mm f/2.8L, [7] 500mm f/4L, [8] and 600mm f/4L [9]), plus the 200–400mm f/4L IS [10] and 100–400mm f/4–5.6L IS II, [11] have a third setting, Mode 3. Mode 1 is normal mode, used for ...