I have a rule. Always know the state of your camera. I went up to Cape Neddick, Maine just to get out in the fresh air. Below is an image of the Nubble Light. I wanted to play with a wide angle shot. It was pretty busy there and this seemed to be a good location to get a different image than what I usually shoot here.
Since it was a bright sunny day, I decided to try an old school technique from the film days. If you forgot your light meter, the saving grace was that on a sunny day, you could set the lens to f/16 and the shutter speed to 1/ASA number of the film. For example if the films ASA number is ASA 100, you set your shutter speed to 1/100 of a second. You will get a perfect exposure.
So since “I know” how my camera is set up, I’ll just put it in manual, set the aperture to f/16 and the shutter speed to 1/250 sec.
Well, that’s a bit blown out. So much for the Sunny Sixteen rule.
Wait a minute. Look at the metadata.
Doh! I violated my rule! I didn’t know the state of my camera! It was set at ISO 320, not 250!
Okay, let’s take the exposure down by 2/3rds of a stop. That’s better. That’s pretty close to what the shot looked like.
Now what the heck was I doing with my D600 set to ISO 300? Crap! It must have been set that way back when were were in Arizona.
New rule. Check over you gear so you can follow rule #1!