How to verify that Nikon SB-28DX AF-assist is working?

Question

I have a Nikon SB-28DX which I am using with an F5. I understand from the instructions how to turn the AF-assist illuminator off. But, how do I verify that it's working? Does it still work with the flash in standby? If no, how do I ensure that the unit will perform AF-assist only, and not fill flash?

In case it makes a difference, I'm activating AF using the AF-on button (that is, custom function 4 is set to 1).

Asked by James Youngman

Answer

Try it in a very dark room. If you can focus, and there's no flash, it's working.

I haven't used an F5 (only much more primitive SLRs), but I assume it will let you shoot with no film loaded so you're not wasting anything.

You've edited the question to emphasize the part about ensuring the unit will perform AF-assist only, which is pretty different from the question of verifying if it is working. From the manual (note the DX and non-DX are identical for film cameras), this flash does not appear to have a mode that does what you want — activate the AF assist light but not actually flash. Some flash makers call this "Spot Beam mode"; Nikon, for flash units that have it, calls it "AF-Assist Illuminator only" (AF-ILL ONLY) or, somewhat confusingly, "Firing canceled". I don't have an SB-28DX, but since the manual doesn't mention this as an option, it's probably not. You can still verify this with the test mentioned above.

Answered by mattdm

Check more discussion of this question.