This adaptor has an internal lens to maintain focus to infinity. The effect of this is to increase focal length of the base lens by about 20%. Used with digital SLR's having a sub-35mm size sensor, this combines with the 1.6x magnification to give approx a doubling of the focal length.

 The adaptor should be used with the camera set to aperture priority auto (Av). The shutter speed will adjust automatically depending on the aperture set on the lens. The adaptor incorporates a ring which enables you to view at maximum aperture and then take at any aperture pre-selected on the lens. At this pre-selected aperture, the viefinder image will be darker than at full aperture. To fit the FD lens to the adaptor, you must ensure that the aperture ring is not set to the 'A' position.

This adaptor is not suitable for full frame digital cameras or 35mm film bodies when using an FD lens with a focal length of greater than about 200mm. It will likely produce a vignetted image.