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Photography tips

A journey in Photography and sharing of how I go about taking various types of photos. Discussions include software and camera equipment and how to make the most of your equipment in a given situation.

HDR to extend Dynamic Range

10/11/2008 03:36

Over the last few years you have probably heard about and seen some HDR or High Dynamic Range photos.  There is basically 2 types of HDR images that you see - the ones that have very vivid and almost cartoonish appearance and the ones you don't recognise as being processed this way.  Well, whenever I use this technique I am for the end result to not be recognised as an HDR if I can help it.  It is a process I use very sparingly.

What I am getting to here is that I recently took a photo of a scene that I ended up doing a whole lot more with.

First off, the scene.  It was just on dusk and the sky had some wonderful subtle pastels and the view from where I was had a wonderful rustic scene leading to houses with the city skyline making a silhouette in the distance.

As you can see the scene really looked like it had potential, but... Look at the sky - all blown out and there is no detail or colour that I could see and it looks a little hazy as well.

What I did was to try several different exposure settings to try and get the most from this scene and no matter what I tried, I simply could not capture the scene that I saw with my eyes.

So, while I was there I decided to take a set of bracketed exposure shots and then try and find one to process or otherwise combine them and process them as an HDR image.

I set my camera up on the Tripod, set it up to take a 5 shot set at 1EV spacing. Using the Remote control I fired away and captured my 5 photos.  The "normal" exposure shot is above.

The -2EV exposure.

This shot captures the colour of the sky that I was after but everything else is very dark with not much detail. The photo also looks quite hazy.

Next, the -1EV exposure

This shot still has a little bit of the colour in the sky and some detail is starting to appear in the brighter parts of the photo.

Now, the +1 EVexposure

As with the 0EV photo, the sky is totally blown - no detail or colour at all. But here we are seeing most of the greens with good detail.  Additionally, there is less haze in the photo.

finally, the +2EV exposure

This photo has even less detail in the sky (if it was possible) and we are seeing the water in the quarry in the foreground looks blown. All of the green is starting to look over-exposed as well.  In this photo we are seeing the best detail so far in the mid distance houses.

Well, when I reviewed the 5 photos and tried my normal processing of them in Lightroom I could not find any 1 of them that I could see good detail in. So, time to pull out the HDR and give it a go.

With the 5 RAW photos, I simply processed a 16 bit tiff from them with no adjustments at all. I then fed the 5 tif images to  Photomatix Pro - a dedicated HDR Application.  Using Photomatix, I thenused the Exposure blending tool to combine the 5 images.  There was a little bit of minor tweaking of the settings needed to maximise the clours and detail.

Once I got the image as good as I could, then I saved it out once again as a 16bit tif- to retain as much of the info as possible. Back to Lightroom and I re-imported the tif to finish it off.  It needed a little bit of adjustment in the areas of brightness, contrast, vibrance and saturation.

The in-between image was a little bit too bright and over-saturated and I simply needed to "tame" these a bit in order to bring the photo back to as close as I could to the original scene.

Here is the finished product

What we see here is basically the best parts of each of the individual photos.  We have the soft pastels of the sky which I wanted, a well defined silhouette of the distant city skyline, virtually no haze, great depth and colour to the mid-ground houses, the green of the vacant land, the rich earthy colours of the quarry wall and finally the mill-pond water with reflections of the trees.

By taking care at every step, I tried to avoid the "typical" over-processed HDR images that some people produce and hopefully ended up with a picture that looks better than the sum of the individual parts.

What is interesting is that while it sounds complex, the processing to get the final image was very easy and took less than 10 minues all up.

For the record, I set the camera up to 100 ISO, 54mm, F8.  The shutter speed varied between 1/60 and 1/4 sec

If you want to see a bigger version of the finished photo - head over to the post in my Photo Blog

HDR is not for every shot, and when used carefully and sparingly it can help you overcome the limitations of the Dynamic Range of your camera.  Most cameras have the ability to bracket, and my Olympus E-3 gives me many choices - 3 or 5 shots at 1/3, 2/3 or 1EV steps.  This scene it was obvious that I needed as much DR as possible, so 5 shots @ 1EV steps proved to be what was needed to get me the shot.  My camera provides me with 9 stops of DR, and the extra 4 Stops by bracketing allowed me to present a scene containing up to 13EV of DR.

When you are next out and about trying to capture a scen that is beyond your camera's DR, take a moment, bracket the exposure and see if you can sort it out in Post processing and add the HDR technique to your photo tools.

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