How Many Exposures For An HDR?

http://www.flickr.com/photos/michaeltuuk/5907380404/in/photostream

HDR Entryway, My House 10mm, f/11, several exposures, ISO 100

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.

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4 responses

  1. Nice write up, my motto, the more the merrier, you can always throw out what you don’t need.

    July 6, 2011 at 10:40 am

  2. I agree that it’s a matter of what look you’re going for. I also agree that you need some shadows, and don’t want to make your image look as if you have a bank of floodlights trained on it. I’ve never used less than 3 exposures, and never more than 13 to create an HDR, and generally use between 6 and 9.

    One thing I’ve definitely learned is that there is no one right way to do HDR, but that there are many, many wrong ways to do it.

    July 7, 2011 at 10:53 am

  3. Great! I enjoyed that post tough I still have some unanswered questions. I normally do 3 with 2 or 3 stops apart. I have done up to 7 or more but when doing panoramic work up to 8 poses or more the thing gets complicated if I do too many variations. Also I have found that with many exposures some pictures did not match in (moving branches and leaves are especially a hassle)

    April 7, 2012 at 10:56 am

    • How many exposures you need just depends on your goal. If you are trying to avoid *all* blown-out highlights and *all* shadows without detail you need to keep shooting exposures until you get detail in all those areas. However, if you need a huge number exposures in a scene like you mention — wind-blown branches — then you need to (1) do an extreme amount of manual masking in Photoshop, (2) give up some details in highlights or shadows so you can stick to using exposures which freeze the motion and/or can be masked more easily, or (3) live with some of that blur. Panoramas with lots of exposures….yeah, just a pain.

      April 8, 2012 at 9:57 pm

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