I am a newbie from England who just discovered your forum. I have a D80 and love it. I encountered a frustrating episode (gap in my knowledge!) when trying to take pictures in underground cave at the weekend. There was zero light and I had the camera on Auto. The flash popped up and the iluminating light came on and the camera would try to autofocus but because the rock had very little definition for the autofocus to latch on to, the shutter release would not fire and so I couldnt take a shot. Please could someone explain what I should do in this situation?
One is to manually focus, but being that the light level is low and the detail is minimal, that will also be difficult. Another method is to just estimate the distance and set the focus on the lens using the distance scale and selecting an aperture that will allow for a margin of error with the DOF. Unfortunately Nikon no longer includes a distance scale with newer designed consumer lenses (what were they thinking!!!).
Another suggestion I read is to carry around a flashlight (I believe you Brits call it a torch). Just shine the flashlight on the rock to attain and lock focus, then recompose and shoot.
Also the focus assist light on the camera has a limited range, using a hot shoe mounted flash such as the SB700 would allow a greater distance with its IR based focus assist lamp.
I rarely venture into manual modes but sounds like I have an excuse to do so. Unfortuately I am a hundred miles away from the cave now but I will practice in the house when it gets dark tonight to see if I can master the technique.
Welcome to Nikonians! Depending on the size of the chamber, the built in Speedlight might not have enough power to light a large chamber. Adding one or more Speedlights to your kit and maybe a tripod will allow you to get creative with the lighting. Good Luck and Enjoy your Nikons!
You can set the camera to ignore the achieved focus status.
An SB-600/700/800/900/910 or SU-800 used IR to create focus marks and many times can achieve focus when the white focus assist light can not.
If the camera can not auto focus, then you will have to manually focus the camera. There should be a M/A switch on the camera body and lens.
With more understanding of DOF, Depth of Field, you could set your camera to f8 and then select the DOF distance to include the area you are interested in. You should be able to get an image with an acceptable range of focused image.
Thanks Marty, thanks George. Plenty of things for me to try out. Would have loved to have the time to experiment with tripods and flash guns but we were in a disused lead mine having floated down an underground river - it was a spur of the moment visit - next time I will be prepared!