Thanks, that is what I suspected. Got to order more and newer speedlights (I just have one SB600) so I can use multiple light sources TTL with digital cameras unless I go through all the trouble of running them manually (which I could do by checking the LCD and adjusting flash output or umbrella distance from the subject until the lighting ratio is what I want).

Maybe as an addition: the flash metering system of the F5 (and other film cameras) is called TTL. The one of the current DSLRs like your D7000 is called iTTL. They work completely different. The SB-600 supports both, TTL and iTTl, so you can use it with your F5 and your D7000 (newer speedlights like the SB-700 and SB-900 only support iTTL). The SB-26 only supports TTL, but not iTTL (it wasn't even invented back then).

You might be able to use the SB-26 in auto mode (metering is done by the flash but does not measure through the lens) and in manual mode.

yes it's different, the only film camera that supports the iTTL is F6

I have a SB-26 flash (from the F5) and was trying to use it TTL (with SC-17 TTL cord) with the D7000 but it wouldn't work TTL, fired full power but no TTL metering. My SB-600 works fine TTL with the D7000 and the SC-17 cord (I know it also works wireless but I was just checking to see if the SC-17 cord was working). Does anyone know why? I wonder if the older film based TTL system is different than the digital TTL system such that you cannot use a SB-26 with digital cameras? Or maybe my SB-26 is malfunctioning?