Photographing the nesting of the Leatherback Sea Turtle was a once in a lifetime event (for me, not for the turtle). It was also quite a photographic challenge.
All of this nesting activity took place in the dark. The illumination was from street lights quite a distance away. My initial attempt to capture an image was with my iPhone camera, as that's what I had with me when we discovered the nest. The iPhone produced an image that was almost totally dark. There was nothing in the image that looked like anything.
I ran back to the room to grab my "big guns", my Canon 7D, my fastest lens and a tripod. I quickly found that there was so little illumination that I couldn't focus the camera by looking through the viewfinder. Heck, I could barely even make out the subject through the viewfinder.
Although I could have easily used a flash, I didn't want to disturb Momma Turtle during this important activity. The last thing I wanted to do is to "spook" her, sending her back to the sea before she was done.
With the low illumination, almost no available light, I focused by taking an image, looking at the playback, magnifying the focus point, and adjusting focus accordingly. Then repeat. Fortunately, sea turtles move rather slowly.
I also used the "live view" feature of the Canon 7D to adjust the focus point. This worked pretty well, but was also time consuming.
The combination of a very fast ISO setting (3200 & 6400), a fast lens (50mm f-1.8), long exposures, a sturdy tripod, shooting in RAW format and using DXO Optics Pro image processing software made these images possible. The EXIF data is available for each image for all of you photo geeks to see. I hope that Momma Sea Turtle approves.