Just bought one of this little gem to try out.  Got it today, still not too sure.

Cost me $126 US plus $30 US express shipping...don't really think it was express as in express though since it relied on Aust Post via EMS took six days than the standard Fedex or DHL which usually take 2 to 3 days at most or you can opt for $10 US for normal shipping which probably takes about 10-14 days. 

Oloong SP-690 Speedlight for Nikon. 

Here's the specs. 

It has the following characteristics 

Here's my pics off a mobile phone comparing the sizes of the speedlites..

The Oloong SP-690 seems slightly taller with one notch angled..as you can see center is the SB-900 and right is the SB-600

The back of the speedlites almost looked identical in comparison to the SP-690 and SB-900

Though this pic from my mobile phone (horrible as hell lol) shows the Oloong to be larger well, it's not really. Physically it's the same size head and height. 

The Oloong's like Yongnou or Nissin 866 (about 260US) or Meike speedlites or speed lights on the market today with iTTL or eTTL for the Canon's or TTL for others like Pentax, Minolta, Sony and so on. 

OK, on the camera (d3s nikon) TTL does function as TTL should but forget about having the TTL-BL mode if you looking to have something close to the Nikon SB-900.. TTL is all you get as in ON-CAMERA TTL!

You get two slave modes.. I've not played with it much (actually less than 5 mins) and back in the bag..  The slave modes according to the manual confused the living daylight what it's trying to say.. lol Don't even bother, makes no sense what is S1 or S2 mode exactly.  Got to play with this to get a better understanding, maybe it's good if all the flash was one brand and maybe the slave or master mode works at it's best.  But if you are using say the SB-900 as the master and the rest as slaves.  The Oloong's behaviour seems to be just manual mode and trigger off when the flashes fired but of course the SB-600 will still function in TTL mode and what group it is set to or EV set accordingly.  

For the Oloong nupe, nothing, zilch! all it does is fire and fire and fire like a remote triggering flash with no CLS advantages or TTL at all or any smarts (manual setting only). The SB-900 as master will not communicate with the Oloong and though there was high hopes for it, nupe.  Suppose if you like to just trigger it and manual setting the SP-690 then no problem there, works like a charm there.  

But if you can't afford an original TTL flash with similar power head as the big 580ex or sb-900 or the larger flashes equivalent in other brands, then I suppose it would be a cheaper investment.  It's definitely a lot bigger flash than the sb-600 or the 430ex. 

The refresh/recycle rates sucks though, the sb-900 or sb-600 almost instantly but the Oloong a tad slower, so a bit of care if you thinking of firing off like mad, it just won't keep up as fast.  Otherwise I still think the flash is pretty awesome and reckon it's definitely be a good backup flash or an alternative flash if the branded flash top end is something you can't afford or justified and still get the bigger lights. 

If you want full CLS (creative light system) from the Nikon's I suggest you buy the Nikon's speedlites a definite advantage when it comes to multiple flash with some awesome features or the similar from other brands of camera flashes like Canon 580ex.. 

I'm also interested to know your views if this would work with pocketwizards flex TT5, mini TT1 and the AC3 zone controller.  As I'm about to embark to buy some soon and including the extra sb-900's, if the flex TT5 would trigger this sucker Oloong in TTL mode I would be damn surprise and could be an excellent cheaper alternative..and use the AC3 for zone controlling instead. :)

Here's a copy of the flash manual for those interested.. 

Oloong SP-690 English Manual.pdf

Definitely an interesting flash to have.. :)