HDR explanation

A few weeks ago when I posted some HDR photos of Long Point State Park I mentioned that the photo was a merge of 5 shots.  A friend of mine was confused by this so I thought I would offer a better explanation.

HDR stands for high dynamic range.  In laymen’s terms your eye can see a lot more levels of light than your camera can.  So when you’re shooting a scene that has areas of light and areas of darkness it’s difficult for the camera to show all of those various levels.  This is where HDR comes in.  By using a tripod to minimize camera movement you can take an overexposed picture of the darkest darks (+2.0 EV in photographer speak)

Notice how the water is overexposed but the rock formations are exposed pretty well (perhaps a bit underexposed still but for our purposes we’ll say they’re good).

Then take an underexposed picture of the brightest brights (-2.0 EV)Now the water is well exposed but the rock detail is completely lost in shadow.

And finally a perfectly exposed shot (0 EV) or so your camera thinks.The perfectly exposed shot is pretty good – water is not too bright, some detail is lost in the rocks but it’s not terrible.

But now if we blend all three shots together and add some contrast:

There is still some darkness in the rocks that personally I am not happy with.  If I chose I could now load this blended shot into PS Elements and use a layer mask to bring out more of the overexposed (top photo) rock formations.

Hopefully this is a better explanation of what an HDR shot is.  I still have a lot to learn about this process but I find I am more and more often bringing my tripod along with me so I can create this sort of shot.  So expect more of these in the future!!


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