8745-2（23.5＊55.5）Fresnel lens (flaky)

Fresnel lens (flaky):

8745-2(23.5*55.5)

Focal length: 21MM

Distance: 15M

Angle: 180 degrees

The Fresnel optical lens can focus the light passing through the narrow-band interference filter on the photosensitive surface of the silicon photodiode detector. The Fresnel lens can not be wiped with any organic solution (such as alcohol, etc.), and the dust can be used first. Rinse with distilled water or plain water and wipe with a cotton wool.

The current camera focusing screens are frosted frosted glass Fresnel lenses, which have the advantages of bright and uniform brightness. When the focus is not accurate, the image on the focusing screen is not clear. In order to cooperate with more precise focusing, a split-image and micro ribbed ring device is generally installed in the center of the focusing screen. When the focus is not accurate, the subject is split into two images in the center of the focusing screen. When the two split images are combined, it indicates that the focus is accurate. The standard focusing screen of an AF SLR is generally not equipped with a splitting device, but is engraved with a small rectangular frame to indicate the AF area, and some focusing screens are also engraved with partial metering or spot metering areas. When an early AF SLR camera focused in a dark environment, it was often difficult to see the focus frame. It was difficult to determine which point the camera used as the focus point. The focus of the new generation of SLR cameras on the focusing screen would emit light, or focus sound Tips for confirming focus in a complex environment. Different types of focusing screens have different uses, and portraits may be better used as a split-image focusing screen. Focusing screens with horizontal and vertical lines or scales are suitable for building photography and document remake; the middle part has no split-image but only micro-edge focusing The screen is suitable for small aperture lenses, it does not have the disadvantage of split side bright side black. Many SLR camera focal screens can be replaced by users themselves. Also known as a threaded lens.