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circular aperture

A circular polarizing filter is functionally the same as a linear polarizing filter as it only passes light vibrating in a certain direction. However, the light passing through a circular polarizing filter differs from light passing through a linear polarizing filter in that the vibrational locus rotates in a spiral pattern as it propagates. Thus, the effect of the filter does not interfere with the effect of half-mirrors: allowing normal operation of TTL-AE and AF functions. When using a polarizing filter with an EOS camera, be sure to always use a circular polarizing filter. The effectiveness of a circular polarizing filter in eliminating reflected light is the same as that of a linear polarizing filter.

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circular aperture

A circular pan is a shot in which the camera rotates 360 degrees around a fixed axis.
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circular aperture

A polarizing filter reduces reflections from non-metallic surfaces and darkens the sky. SLR cameras require circular (rather than linear) polarizers to prevent focusing and metering problems associated with the camera s beam-splitter.
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circular aperture

Converts linear polarized light waves to circular polarized light waves. Required whenever polarizing is desired using autofocus cameras and cameras that have semi-silvered reflex mirrors.
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circular aperture

Certain Canon lenses feature a new Circular Aperture diaphragm unit, which uses curved aperture blades to provide for a more rounded opening as the lens is stopped down. It s especially effective at rendering out of focus background highlights as natural rounded shapes. In lenses such as the EF 70-200mm f/2.8L IS lens, the lens opening is virtually circular from f/2.8 to f/5.6. These lenses retain all the benefits previously available with Canon s Electromagnetic Diaphragm smooth and consistent stop-down operation (even at up to 10fps with the EOS-1v), near-silent aperture control, and total absence of mechanical levers or switches in the lens mount.
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