On Fri, Oct 12, 2012 at 10:51 AM, Darren Addy <pixelsmi...@gmail.com> wrote:
> On the other hand it is worth remembering that you aren't touching the > surface of the sensor itself, but a filter that is in front of it. I > wonder how sensor cleaning works on cameras with no anti-alias filter. > Is there still a hot-filter in front of the sensor (for IR)? When the D800E came out, there were diagrams of its filter arrangement, e.g.: http://photographylife.com/nikon-d800-vs-d800e In the normal D800, the arrangement is something like this: [ AA - ] [ IR ] [ AA | ] [ Sensor ] The AA filters are made of birefringent material, which splits an image in two, depending on the polarization. One AA filter doubles the image with a slight displacement in the horizontal direction, and the other doubles the image slightly in the vertical direction. There is an IR-blocking filter between them. In the D800E, the arrangement is: [ AA - ] [ IR ] [ AA - ] [ Sensor ] That is both AA filters operate in the horizontal direction, but in the opposite sense--the first filter splits the image, and the second recombines them, so the net effect is as if there were no AA filter at all. I presume that they chose this method because the filters all have some refractive power; by using the same number and composition of filter layers, they can keep the camera mechanically identical (i.e. with the sensor and filters the same distance from the lens mount). If they removed the filters, they would have to adjust the sensor position slightly. It's sort of like the "mandatory" clear filters in lenses that take internal rear filters. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
