First, there were 12 for the SAO. Then 3 for the USAF. I thought that was great because I knew of the wherabouts of 12 cameras. But, now, I’ve found out that an extra 2 were built for the USAF. This kind of makes sense as I was pretty certain that there were more than 3 BNCs out there with the USAF-style base. I’m not sure, however, if one of these extra cameras was the slitless spectrograph that Boller & Chivens mentions on their website. So, the search continues…