Using HDR instead of Fill Flash to Deal with High Dynamic Range
A Guest Post by Suzy Richards
HDR has made a very negative name for itself but in some situations it can be a life saver. One instance where I have started to use it recently is in situations where I would have previously used fill flash if I wanted a more even exposure.
To experiment with this method I set up a deliberately problematic scene. A gloomy garage with window light reflecting on a metal surface. Dark shadows and extreme highlights on the subject – a car. Fill flash can also be used to reduce the contrast in a scene by artificially lightening the shadows. With window lit scenes or shiny subjects you can get an annoying flash reflection or odd shadows so I decided not to use flash and try the HDR route.
I set up an initial shot with just basic settings. Normal exposure with a small amount of negative exposure compensation to reduce highlight burn. A low iso to maximise available dynamic range. On checking the histogram and the blinkies in image review it was obvious it was going to need something extra. The result was the car1 image.
I tried the 4EV in the HDR menu as a starting point. That was better but still not adequate. Judging by the histogram only the maximum 6EV setting would be enough. There was still a little amount of highlight burn but as that was mainly a window reflection on metal it was fine. It is also worth experimenting further with positive and negative exposure compensation and checking the histogram and blinkies to see which combination of HDR, low iso and exposure compensation gives you the most pleasing results. Change one value at a time and review the image each time to see whether your changes are an improvement. The final result was car2.jpg.
Without knowing it was an HDR you’d probably have no idea as it is not the sort of scene you generally associate with it. As can be seen from the original car1 image the shadows are dark and there is a burnt out highlight on the bodywork. In the HDR car2 image you have some background detail, detail in the shadows and the highlight is also more controlled. The difference is quite subtle but it looks more of a balanced exposure and natural scene.
To create an HDR without an in built mode on your camera you need to use the bracketing function and bracket over the same distance eg 4 ev so -2, 0 & +2 with 3 exposures. Generally 3 or 5 images are sufficient. You can then use software to combine them. The most common of which is photomatix. It will probably need some more tweaking as generally photomatix seems to err on the side of garish.
Other situations scream HDR loudly so I no longer bother even trying with normal exposure.
The church sceneis one such situation. As soon as I walked in I knew. 5EV seemed to be about right to retain some mystery. 6EV seemed to over emphasize the green reflection from the window which I didn’t want. It’s quite common for churches not to want flash photography so this was ideal. I’m also a tripod hater so having a method which generally allows hand holding is also high up on my list.
Using HDR in these situations has proved to me that it has a real use in photography.