Focal Reducer Mount Adapter for Pentax K PK Bayonet Lens to Sony NEX Mount 5 6 7 Camera

In common lens adapters, cropping effect occurs in all APS-C digital cameras with 1.5x magnification. This adapter reduces focal length to 0.72x , to adjust the image size to near 1:1 so that the focal length of the image is close to actual focal length of the lens, e.g. 50mm x 1.5 x 0.72 = 54mm. It helps to increase the maximum aperture to 1 stop, and you can use it faster by 1 stop. Blue spot will occur if lens is shot to sunlight or lamp directly.