I learned a valuable lesson on why you should shoot raw. Today I went to the Tremont area in the Smokies to look for wild flowers. This is my favorite area in the park. I was a little late for wild flowers as they were very sparse. No matter the stream was great and everything was green with fresh foliage. 
I spent the afternoon photographing at various points along the stream without even looking at the metering mode setting on my camera. I assumed I was in multisegment and with my past experience photographing steams this setting nailed the exposure without fail. I was so confident in the exposure I didn’t even check the histogram my camera has for each photo.
It was getting late so I drove home and I knew for a solid fact I had correctly exposed photos. Well I popped the memory card in my computer and ACDSee downloaded the photos on my computer. I quickly noticed that the photos were all dark and very underexposed. Oh no I thought my camera is broke. I grabbed my camera and looked at my settings. It was set on spot metering. I remembered the last time I used the camera I was photographing a scenic in Cades Cove with tricky lighting that required spot metering. With me using multisegment most the time I just made a dumb assumption.
Now spot metering is not bad for streams. Just meter off of something that is medium green or tree bark and you nailed the exposure but if you don't know you are using spot there is a problem. With multisegment you meter the whole scene for your exposure. That means you compose your photo and your meter takes into account everything in the scene. With spot metering the small center circle in the viewfinder which comprises only 3% of the scene is what it will meter. With streams the center circle is usually placed right on the bright white water and your camera will greatly under expose the scene. See the problem.
I am glad I shoot with raw because with raw I can make an underexposed photo correctly exposed easily. If I shot with jpeg I would have deleted all my photos and chalked up the day as a complete loss. As you can see from the photos posted raw format saved my photos. Moral of the story always check your camera settings and never assume. Moral number two is raw is super groovy.
