Why use 1/4 or 1/2 power with 105 strobe?

Never one to fear asking a dumb question - Why/when would you use less than full power from a strobe? My Nikonos offers full, 1/2 and 1/4 power options. I'm guessing it's to use the strobe as sorta fill flash with available light??? How do you know which to use? And what's this business about using a a strobe manually??

I'm still a newbie, but from what I know you pretty much hit it right on the head. Sometimes you just don't want all that light. Especially if you are doing a near far shot (check this one out: Image by iflyprops (Copyright) posted at ScubaGallery) where you only wish to light something in the foreground. Also sometimes if you are shooting against sand, or something more reflective it is really easy to wash your subject out. Also take into consideration ambient light, depth, etc. If I screwed anything up anyone let me know !

I shoot full manual and bracket the exposure with the flash. I shoot digital and if the exposure isn't right I change my F stop and shoot through the strobe settings again and repeat if necessary.

Joe

Big Sky Dave:

Never one to fear asking a dumb question - Why/when would you use less than full power from a strobe? My Nikonos offers full, 1/2 and 1/4 power options. I'm guessing it's to use the strobe as sorta fill flash with available light??? How do you know which to use? And what's this business about using a a strobe manually??

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TTL works great for macro, but not so well for wide angle. Many wide angle shooters determine a manual setting for their strobe at f8 from a distance of 3 feet and manage ambient light with shutter speeds. For 100 speed ISO setting or film speed, a Nikon 105 should be set full power at f8, 3 apparent feet. Reduce strobe power by half when shooting from 2 feet. I don't think there is a 1/2 power setting, but adding the diffuser reduces output by a stop. By shooting manually, you don't rely on a subject filling the frame to let TTL work (a TTL shot of a small object in the foreground will overexpose). If you have a close focus lens, such as a Nikon or Sea & Sea 15mm, you can focus to 1 foot. Take the diffuser off and reduce power to 1/4 for close focus (1') wide angle. The purpose of a strobe in wide angle is to provide color to the ambient light, as no strobe can "light the ocean" in wide angle photography. See http://claycoleman.tripod.com/id96.htm for an example of a touch of strobe in a wide angle shot to add color and depth. -Clay

What I'm trying to do right now is crawl around in shallow 1-3 foot deep trout streams and capture shots of trout. So far I have some great shots of mating crayfish! Those were taken macro. The shots of I've tried of trout come out almost black. I'm using a Nikonos and 35mm lens for those. The ambient light of course is not black. I've been using TTL. Am I likely to have more realistic looking shots if I switch to 1/4 power. Most of the fish appear about 3 feet away. Any other ideas appreciated. Thanks.