Monday, January 20, 2014

Returning to HDR a fresh

I have been taking bracketed set for a long time, particularly I am not certain of the lighting conditions will be interpreted by the cameras light meter. Cases such as sunrise, sunset, strong contrast/shadows are good examples. Even if the exposure is off by also taking a couple of extra photos  with a little extra and less exposure (which is easy on digital cameras) you then have a reduced the risk of missing a good opportunity. Most digital cameras let you do this by changing the EV (Exposure Value) sometimes called the exposure compensation. This is a much simpler number to understand that the interrelation of lens aperture (f-stop) and exposure time (speed). Each unit of EV is equivalent to doubling the light (or in simple terms one f-stop). The EV setting on most cameras are relative to the exposure selected, so +EVs increase the light that lands on the sensor (over exposes) and negative –EVs decrease the light that lands on the sensor (underexposes). This is done by the camera either changing the f-stop and/or speed.
You will probably have to read your camera manual but it is relatively easy to set up most DSLR to automatically taken an appropriate EV set. For example I have my Pentax ‘s User mode set up to take a set of 5 images at steps of 0.5 EV from -1 to +1 EV. I press the shutter … click, click, click, click & click … I get the exposure in pretty rapid fire (depending on the speed of the exposure). By having this already programmed there in user mode I just have to turn the mode dial and press the shutter. It’s very convenient and a good way to quickly fill memory cards but it bring me comfort that I will get at least one half decent exposure. On my Canon I tend to just set it up manually and typically just do 3 photo -1EV, 0EV and +1EV. This is a little more work but I tend to go for my Pentax when it is an important subject.


Now the selection of the best exposure and whether you want to post processing the set as HDR can come later. Even though I am now quiet at ease with the HDR process it still takes time and I have to jump back and forth between programs so I tend to only do a few HDR photos at any time (a lot of the sets just remain unprocessed). That is where a minor side benefit of google+ auto backup comes into play. As it is busily (ok its slowish but I’m not complaining) uploading my old images it tries to run HDR on any suitable sets it finds (it doesn’t do everything, but it does look at many more than I did) and each day I seem to get a new notification of new auto awesomes to look at. I have taken a renewed interest it those it has chosen to do as HDR. Not all are good, but they have been worth a look, perhaps the better ones will be worth a second look and perhaps revisiting the post processing that could be done. I’m not ready to hand over the care and refinement of my photos to an anonymous algorithm quiet yet, but I am keenly interested it what it can do with my photos.
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