Sync speeds and intimate concerts

As some of you may know, I've been spending some time over at my friend Darren's place aka the Cave of Comics.  Darren has found a gig that gets several good folk music acts into his basement every month or so and as a result, I get to take pictures.


Over the weekend, I got to borrow my friend Tracy's D90 so I could have both a wide and my zoom lenses going at the same time.  I mistakenly thought that since the D90 has the same sensor as my D300, most of the rest of important bits would be the same too.  Oops!  The flash sync speed is slower on the D90 than it is on the D300! Pictures available at http://photos.davidporterphotography.ca/sean-cotton

Normally, when I'm shooting in Darren and Cathy's basement, I use a few flashes.  I nuke the walls using a red gelled flash pointing behind Sean at about 1/4 power and a second flash at about 1/32 power bouncing off the ceiling in order to get a white light hitting the artists no matter where they move while singing (People were complaining about yellow and red skin, go figure).  I sit in the back row taking pictures, where I can't adjust the angle or the power levels of the flash without interrupting people.

Why do you care about sync speed?  Well, on most CMOS SLR's, the shutter closes either from the top or the bottom (go figure).  Roughly put, the sync speed is the fastest shutter speed that all the light from your strobe can reach the sensor.  Strobist has a really great article on this.  Also, whether the shutter closes from the bottom or the top depends on the model.  The D90 shutter closes differently than the D300 and they have the same darn sensor and share a lot of other bits too.  If the settings on your SLR are making everything black except what you paint with a strobe, you get a dark band on the bottom or top 1/2 of your frame (left or right if you hold it vertically).  While David Hobby and Chase Jarvis can do some really cool things with this in day light, if you set the exposure to be black where your strobes aren't hitting, it matters a great deal!

Why do I care?  I had to crop a bunch of photos prior to posting them today in order to get rid of the black band on the bottom of the frame (see the smaller picture below).  No real harm done and lesson learned.