item #NikonFlashNo36. item #nikonflashSB20No25. Nikon Autofocus SB-20 Speedlight. Introduced to supplement the F501, the autofocus flash SB-20 was designed originally as a companion flash unit for the second Nikon AF SLR camera, the F-50. In many ways, although it was designed as an AF flash, but most of its features can also be use on any of the TTL or non-TTL Nikon bodies. As the flash has an standard ISO-type flash foot, and during its introduction, Nikon F3 was still a flagship model in the Nikon SLR lineup, so it needs a flash coupler such as AS-4, AS-7 (TTL coupler AS-17) to bridge for the Nikon F3. For other Nikon bodies that has ISO-type accessory shoe, the connection is direct. The battery terminals are clean. Tested. Condition 9-.