External AF Assist Illuminator Contacts

If you have the SC-29 flash TTL extension cable, then two metal contacts on the SB-800 enable the unit to function with the Wide Area AF Assist Illuminator. Basically, these two contacts match up with the SC-29 cable so you can activate or deactivate the AF Assist function. The SC-29 has a lever switch on the front that allows you to turn off the SB-800 AF Assist lamp and use only the AF Assist lamp at the other end of the cable, mounted on the camera body (figure 5.64).

Figure 5.64 - The AF Assist contacts allow you to use the SC-29 cable for auto focusing in dark rooms.

Why would you do this? Let’s say you have the flash mounted to the TTL cable but you are bouncing the flash off the ceiling or a wall. In this situation, the flash will emit the AF Assist pattern onto the ceiling or wall, not at the subject. But if you purchase the SC-29 cable, you can still use the AF Assist pattern function because there is an additional AF box that mounts on the camera body. Problem solved!