The HD DGX 1.4X converters have genuine Gate Array IC (Integrated Circuitry). This means the converter's unique circuitry maintains signal integrity between the camera body and lens. The 3~5-element design made with high quality multi-coated optical glass supplied by Hoya Corporation, the world's largest manufacturer of optical glass. Full AF operation with the TELEPLUS HD DGX 1.4X is possible using a camera lens with an open aperture of F4 or brighter. Please be aware that AF will work properly only if there is enough light and contrast on the subject to activate the camera's AF sensors properly. (Manual focusing may be necessary when using lenses with smaller open f-stop values than that given above.) The TELEPLUS HD DGX converters have updated circuitry to record exif data more accurately.In the exif exposure data (meta-data recorded with a digital picture) TELEPLUS HD DGX converters record the equivalent aperture and focal length of the lens setting plus teleconverter. Optically and mechanically they are identical to the prior high-quality TELEPLUS HD DGX converters. Lens performance has been improved dramatically as compared to the MC4 and MC7 models. The improvement in resolution is especially marked, 180% respectively in comparison to the current models.