Attached Link: http://www.renderosity.com/mod/tutorial/index.php?browse§ion_id=31

Here is my second attempt. The light is nature at work and selective exposure.  I saw these fine clouds with early evening sunlight piercing through and adding much contrast...so, take some photos! 

I used "spot metering" so the camera would not average the etire scene but would take a selected part at representing middle gray then work out the rest from there.   About all the post work was a touch of saturation and resizing to post.  I saw the beams of light through the clouds and that made it a must shoot for me.

In 2007 I put up a tutorial on "spot metering" here at Renderosity and you are certainly welcome to download it (.pdf file).  The link will get you there if you want to take a look. Scroll down the page a little to find the tut. 

You folks have some very creative, fun and fine "light" shots here.  TomDart.