Monday, March 14, 2011

Neil vN Tests Nikon's Boosted 1/320 Sync Speed

One of the cool things about the Nikon D300, D300S, D700 and D7000 is that they can boost the flash sync speed above their normal sync speed of 1/250 to a third of a stop higher to 1/320.  The manual (at least on my D300) cautions that using this 1/320 sync speed will cause a reduction in the effective flash output but it is still more efficient than high speed sync (which has a 2-stop penalty).  It was always a mystery to me as to how the boosted sync speed works, and what the power loss was.
 
Neil van Niekerk just posted an article that tests the 1/320 sync speed and compares the result with 1/320 high speed sync, all using manual flash at full power:
 
I'm amazed that the reduction in effective flash output with the boosted 1/320 sync speed is not as significant as I thought.  It's certainly far more efficient than high speed sync.
 
Neil does note the slight darkening along the edge of the frame and for that reason would prefer not to use 1/320 sync.  In my case, I usually use high sync speeds in bright ambient conditions, and the darkened area would normally be illuminated by ambient light anyway.  So for my purposes, I would definitely turn on the 1/320 boost option.
 
On a related note, David Hobby found out that the D7000 can fooled into syncing at 1/400 (up to 1/4 manual power) and 1/500 with some darkening of the frame: http://strobist.blogspot.com/2011/03/nikons-d7000-sync-dial-goes-to-eleven.html  (His rationale for going all the way to 1/500 despite darkening is the same rationale I have for turning on the boost option.)  I'll test out the 1/400 sync speed on the D300 as well -- it may just work.