Nikon AS4 AS-4 FLASH COUPLERS

NIKON FLASH UNIT COUPLERS AS-1-2-3-4-5-6-7,10 & 11. Nikon Flash Unit Couplers provide direct electrical connection between a Nikon camera body and an electronic flash unit when the mounting foot of the flash does not fit the camera's built-in accessory shoe. The flash then can be used without a sync cord. Six types of Flash Unit Couplers are available according to the type of camera and flash combination

Nikon Flash Couplers' Compatibility Graph
Flash Unit Coupler	Coupler	Camera	Electronic Flash Unit	Remarks
AS-1		Nikon F and F2 Series	Nikon Speedlight SB-15, SB-16B, SB-19, 20, SB-21B, SB-22, SB-23, SB-24, and other electronic flash unit with ISO-type mounting feet.	*1
AS-2		Nikon F5 and F4 (with DP-20, DA-20), F3P, F3H, F801, FA, FE2, FM2, FM2n, F-501, F401, F-301, and other cameras with ISO type hot shoes.	Nikon Speedlight SB-7, it permits flashes with F or F2 sockets to be used on F/F2 cameras with ISO hot shoe.
AS-3		Nikon F3 Series	It permits flash units designed for Nikon F and F2 to be used on Nikon F3. Examples, older BC- units or SB-7E etc.
AS-4		Nikon F3 Series	it connects flash WITHOUT a cable attachment functions but with a ISO-type hot shoe. Other newer units also usable Examples:- Nikon Speedlight SB-15, SB-16B, SB-19, SB-20, SB-21B, SB-22, SB-23, SB-24, and other electronic flash units with ISO-type mounting feet.	*1, *2
AS-5		Nikon F2 Series	It reverses the usage of Nikon flash designed for the Nikon F3 special flash foot to be used on older Nikon bodies such as Nikon F and Nikon F2 models. Nikon Speedlight SB-12, SB-16A, SB-17, SB-21A	*3
AS-6		Nikon F5 and F4 (with DP-20, DA-20), F3P, F3H, F801, FA, FE2, FM2, FM2n, F-501, F401, F-301, and other cameras with ISO type hot shoes.	It works in principle as the AS-7, where Nikon Speedlight SB-12, SB-16A, SB-17 or special unit such as SB-21A designed for the Nikon F3 to be used on Nikon bodies with a standard ISO-type hot shoe.	*3, *4
AS-7		Nikon F3 Series	This was specifically designed for Nikon F3, Where all ISO-type hot shoe Nikon flash can be mounted and used on the Nikon F3.	*5
AS-8	See Nikon SB-16 A/B	Nikon F3 Series	Basically the base module of the connecting part of the SB-16A, designed with a Nikon F3 flash foot.
AS-9		Nikon F5 and F4 (with DP-20, DA-20), F3P, F3H, F801, FA, FE2, FM2, FM2n, F-501, F401, F-301, and other cameras with ISO type hot shoes.	Basically the base module of the connecting part of the SB-16B, designed with a any Nikon SLR with an ISO-type hot shoe.
AS-10			The module has a direct connections for additional flash (off camera), it is used with sync cords such as SC-18 TTL multi-flash connecting cables. It has a tripod socket for independent use with a separate flash.
AS-11