SB-28 keep it?

Sell it. It won't work as a wireless slave like the SB-600 or SB-800. I see a new lens in your future.

Bob

 

With a peanut slave attached to the bottom of it, you can get it to fire wirelessly with your SB800 as your main ight source. I have one and have done it that way. You won't be able to control it's output with the SB800 though. You'll have to set it's power manually.

 

Steve is right of course but it will only be a matter of time before you wish you had another SB800. I would sell it now while it still may be worth something.

 

Hey, if you're just using it as an accent light,

Why not put it to good use? I have to disagree with Gordon on selling it "while it still may be worth something". It's not "worth" much now, and won't be worth much later either.
What you need to do anyway, is use your onboard flash, turned down to 1/16th power, to fire your SB800 off cam, anyway. Your main should be WAY off your camera to look best, say 20-45 deg off camera, to prevent flattening out the features of the subject's face, to maintain desirable shadow modeling. You could either use your onboard flash for fill and your SB28 for an accent light, be it a hairlight, background light, kicker, or whatever.
Are you going to be using these for portraits, or what? You never said.

 

A man of few words :-/

So, what do you think about my suggestions?

 

I am with Steve on this one you can never have enough slaves around and running the flashes in manual is still the best way in some situations.

Martin