During a trip to San Antonio, my wife and I decided to visit the Natural Bridge Caverns. Of course, I packed my camera and flash (Nikon SB-900) — but I honestly wasn’t sure what to expect. After all, we would be descending into the ground and light would, at best, be provided by pretty dim lights.
But I figured it’d be a fun test of my equipment.
I started shooting as soon as we entered, and shot pretty much constantly until we again entered the world of light. I ended up with more than 400 images to weed through.
My approach was fairly straightforward: For the most part, I used the SB900 in the hotshoe of my Nikon D300s. I would pull the flash off the camera (relying on the Nikon Creative Lighting System set on TTL) when I was shooting objects that were close to my location.
I initially set my camera on ISO 200 and manual, with the shutter speed locked in at 1/250 of a second and the aperture at f8.
The problem with my settings manifested itself when my flash overheated and shut down. Now, I had read that one of the shortcomings of the SB900 was that it overheated, but I’d never experienced it before. However, in the caverns two factors worked to shut down the flash: 1) I was shooting LOTS of images quickly, and 2) the darkness was forcing the flash to perform at peak power.
After the flash cooled down, I modified my settings by upping my ISO to 400, reducing my shutter speed a bit and opening up the aperture to f4. This would allow for subjects to be recorded with less light. At least that was my theory.
Believe it or not, I could actually hear the difference. At the original settings, the flash would make an audible “pop” when it triggered; the sound of the flash firing was noticeably less after adjusting. The flash did shut down once more, but that was my fault because continued shooting high numbers of images.
What amazed me most, however, was the fact that focus wasn’t an issue. The images were tack sharp, even though I had the autofocus assist light turned off.
What this experience proved to me is that technology has advanced to an amazing level, allowing autofocus to work in extremely dim light. And flashes will put out an incredible amount of light — as long as the photographer works within the unit’s specs.
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