How Many Exposures For An HDR?
I had a question on flickr regarding how I process (more detail) and how I pick how many exposures to use. I don’t have a big technical tutorial to give but I’ll post a few comments and point to some links.
In the “mini hdr tutorial” link below I give some general thoughts along these lines and at the bottom of that post you’ll find links to several “real” HDR tutorials. In the “using only the good exposures” post are some related ideas as well. I’d sum up how to pick the number of exposures like this: “Use as many exposures as are required to show all the detail you wish to show”. What does that mean? First, you need to decide how much detail you want. Do you want every detail in the shadows (I rarely do…eliminating too many of the shadows/blacks in an HDR generally results in “bad” HDR…just my opinion of course)? Second, you need to be checking your LCD and/or histograms to make sure you take the range of exposures to get your highlights and shadows exposed “properly” (ie according to what you hope to get in the final result). I *usually* try to get dark enough exposures to completely eliminate blown-out highlights but for my longer exposures I wing it — I decide when I’m done by chimping and just eyeball it. Note that I don’t *always* try to prevent blown-out areas in the final image — it just depends on the look you’re going for (here’s a non-HDR example where blown-out highlights are purposeful – https://michaeltuuk.wordpress.com/2011/05/09/backlit-portrait-experimentation/). The image above of my home’s entryway is an example of an HDR where I left in both blown-out highlights and some shadows. This old image was simply an experiment and I never intended to show it, but it’s a good example for this post. The blown-out window gives a fine sense of a very bright day and I feel no need to show any of the detail of what’s outside. I have no recollection of how many exposures I actually used for the final image.
In this post (https://michaeltuuk.wordpress.com/2011/01/29/using-only-the-good-exposures-for-hdr/) I show an HDR where I took 3 exposures in the camera, but only ended up using 2 of them.
In this post (https://michaeltuuk.wordpress.com/2011/03/09/mini-hdr-tutorial-ish-thingy/) I used 7 exposures. What I didn’t say in that post is that I wanted to have a bit more shadow detail than my typical HDRs. In this case I found that the image still “worked” (and worked better IMO) with less shadows due to the stark contrast between the very warm, yellow tones of the pasture beyond the cabins and the very cold, blue/gray tones of the shadows in front of the cabins. It took those 7 exposures to get the desired range of exposures from bright sky to dark shadows. I probably took more exposures than that but I don’t have access to my Lightroom catalog at the moment so I can’t verify that. At the bottom of this post note that there are links to “real” HDR tutorials which you may find useful for further thoughts on choosing the correct number of exposures.
I’ll add some info on the other aspects of my (typical) processing in a future post.