forestgnome said:
... Another question; doesn't the shutter speed need to be either 60 or 90 to be in synch with the flash?
What we need to know first is that flash synchronization (synch) means the flash will be at its highest power (brightest) when the shutter is fully open to expose the full frame of film or electronic sensor.
There is no universal answer to this question about synch speed. It varies from one camera model to the next. Best advice is to read your camera manual.
(I shoot with one Nikon digital SLR camera that synchs with flash to 1/500 sec; the other camera I use is a newer Nikon model with a top synch speed of 1/250 sec. I do note that in low light conditions both cameras default to a shutter speed of 1/60 sec when I attach a flash unit and turn it on if I am shooting in aperture-priority mode with no other special settings.)
(Older film cameras that use focal plane shutters sometimes have a flash symbol next to the highest shutter speed at which the flash will synchronize. Use that or any lower shutter speed and you will be OK. Most cameras that use leaf type shutters will synch with flash throughout the full range of shutter speeds.)
One thing to remember is that the duration of the flash burst is the primary controller of exposure duration in flash photography. Electronic flash units ("strobes") fire at high speeds -- 1/500 sec or less flash burst duration. The Nikon SB-800 unit that I use fires at a range of 1/1050 sec on full power to 1/41600 sec at 1/28 power. This is what gives flash such great ability to "freeze" moving subjects or negate the effect of camera shake.
But -- and there always is a "but" -- things can become a little more complicated using flash when there is a fair amount of ambient or existing light, and/or you shoot at a high ISO film or sensor setting, and/or you use a relatively large lens opening (low f/number). Any of the three can complicate, but in combination they can complicate matters quite a lot.
In this case what happens is that if either the camera or subject moves, a blurred "ghost" image may appear in the picture. It can be notably distracting in some cases. In other situations it can add a sense of movement or dynamics to the photo. A lot depends on what is blurred and where the blur lies.
I shoot a lot of sports using flash to supplement available lighting, and so blur can be a real problem at times. The most distracting blur has a sharp image with blur leading out of it toward where the pictured action ended. It just looks distorted, distracting and "amateurish." Put the blur behind where the action ended, and you sometimes get a nice effect that helps emphasize the motion / action.
Luckily, many modern SLR cameras have what they call a "rear curtain synch" option which has the flash fire at the end of the time the shutter is open rather than at the beginning. Rear curtain synch puts any blurred existing light exposure behind the action, where it either adds to the effect or is minimally distracting.
Some of these cameras also have a "slow" synch mode in which the exposure is based on rendering the background naturally and the flash is used to illuminate a less lighted subject in the foreground. My camera enables this feature for shutter speeds as slow (long) as 30 full seconds.
Using flash to supplement exisiting light is a powerful technique for producing very striking photographs. I'm not sure it applies much to the forestgnome style of prowling the woods for shots of moose in full dark, but may be useful in a lot of other outdoor photo situations.
BTW, the latest forestgnome moose appears underexposed, to me. Exposure appears to be better -- and probably the flash control system based its readings on -- the tree in front of the moose. Underexposure also may result from being out of or near the limits of the range for the flash unit's output.
Using flash outdoors at night is tricky, tricky, tricky business. Or has that been said before?
Sorry to ramble on about this. There just is so much to know, and share ...
G.