True at the time of writing: human eyes can handle high contrast much better than cameras. Even the latest professional cameras can't "see" as well as the average human when it comes to photographing scenes where both very bright and very dark objects are present.
I live in Arizona, a land of many contrasts, so I know this first hand. How many times did I find myself trying to capture a cave surrounded by glowing sandstone cliffs while at the same time wanting to show some of the interior of that cave, with all its nooks and crannies? The answer is it happened many, many times. Just this past weekend I visited one of Arizona's most popular attractions, the Tonto Natural Bridge, the largest natural travertine bridge in the world.
So what to do when you encounter such a great location, but the sun is almost shining in your face and darkness is all around you? You either avoid the high contrast scenes altogether, change the composition or wait for the right time of day when the contrast is lower... But then you are most likely going to lose those nice colors and great light, and going to end up with a dull image you don't even want to take.
How do you like this image, where the arch walls are properly exposed, but everything else is either too dark or just washed out? And how do you like that white hole in the center of the image?
There are the photography purists who say that you should be bound by your camera's limitations, be creative and stick with it. But then there's the other crowd (and I'm part of it) who says that photography is a craft, cameras are just tools and you should be free to capture the image through whatever means available, be it on a smartphone, the latest 100 Mpix medium format camera, film or digital, you name it.
With that in mind, HDR comes to the rescue! (H)igh (D)ynamic (R)ange is, simply put, a way to capture more than your camera natively can, by means of taking multiple pictures at different exposures and then mixing them to obtain the desired exposure.
That's exactly what I did: I captured two more images, one underexposed and one overexposed compared to the original image. Now each of those extra images gets parts of the scene properly exposed. You can now see the sky is blue and water is streaming down from the top -- what a great view!
The third image is overexposed, however it makes all dark areas visible again.
Now I have all the "ingredients" that I needed. It's up to me to decide what is bright and what is dark in my final image, the overall mood based on my artistic preferences and my vision of the subject, not based on the limitations of my camera. I can make it all dark and moody, a sunny day at the beach or anything in between! This is what I came up with by using HDRsoft's Photomatix, one of the best HDR tools out there:
Indeed, the sky is blue and the arch walls are partially lit. I like a bit of contrast in my images, so the final image has a bit higher contrast and slightly more saturated colors but the overall result is a pretty close resemblance to what I saw that day. The main gain in the final image vs. the normal exposure is the arch's opening which reveals the blue sky and waterfall, but that's just my vision, yours could be totally different!
Regardless of how you like your images one thing is certain: using HDR you have the option to compose the image however you like it. A single shot of the arch above would simply not have all the information to produce a true-to-life image but, more importantly, would limit your creativity and vision.
Of course, one can go crazy while using HDR and many do. I, however, like the more moderate approach to HDR, usually called "exposure fusion" which attempts to keep things real, close to what a human eye would see if present at the time when the photo was taken. Many applications such as Adobe Photoshop CC and Corel PaintShop Pro offer exposure fusion as an included option and it works reasonably well. But if you want the best results then get a dedicated tool that only does HDR.
The future is coming fast. We're getting very close to the time when digital cameras will be able to handle high contrast just like we humans do. That will save us some time and effort but, in the end, it all comes down to the photographers' vision.