Friday, April 2, 2010

End of a day

50mm at f/8.0, 8 exposures merged to HDR in Photomatix

Jess and Logan and I went for a walk last weekend along Cabrillo Boulevard, the road which runs along the coast in front of downtown Santa Barbara. I liked the light shining through these palm trees, and I had been itching to try making an HDR image using more than 3 exposures. So I set up my tripod and made Jess and Logan plop down on the grass to add some interest to the scene. Keeping Logan "posed", of course, meant holding him down and tickling him :).

This is an HDR image composed of 8 exposures, and for once, it's not super noisy! At first I chalked that up to the 8 exposures as opposed to 3, but I tried processing it with just 3 of the 8 images and that wasn't noisy, either. There may just be something unique about the lighting of this scene that made it less noise-prone than my other attempts. Either way, I'm happy to not be complaining about noise!

Here are all 8 exposures laid out. They range from -3 1/3 stops to +3 1/3 stops, but they're not evenly distributed within that range.

Figuring out how to take all of these exposures quickly was an interesting challenge. I used a combination of the camera's auto-bracketing feature and exposure bias. I set the auto-bracketing to take 3 exposures at -1 1/3, 0, and +1 1/3 stops. I then used the exposure bias to take three bracketed shots each at -2, 0, and +2 stops. For those of you keeping count, that's a total of 9 images--I must have misplaced one or something.

An interesting part of this process is that it takes some time to take all of those exposures, and subjects can easily move in that time (especially when one of the subjects is a toddler!). This movement results in "ghosting" in the final image. Here's what Jess and Logan looked like straight out of the HDR process.

Those faint lines come from their changing positions in the different exposures.

To fix this, I picked one of the exposures where Jess and Logan were exposed well and looked best. I happened to pick the 6th exposure. I made a little effort to adjust this image so that it at least somewhat matched the HDR image in terms of exposure and color.

I then brought this exposure plus the HDR image into Photoshop, auto-aligned the two images, and then used a layer mask and a brush to replace the ghosted version of Jess and Logan with the one from the good exposure. If you look closely, I didn't do a very stellar blending job there; hopefully my technique will improve over time.

Sadly, I don't think there's anything to be done about the huge streak of lens flare on Jess' back, but what can you expect when you shoot straight into the sun?!

This was a lot of fun, and had me all giddy to try this "many-exposure-HDR" technique on some other subjects. As I'm writing this, I've already had a chance to apply this technique on a recent sunrise at the beach, and I'm excited to share the results with you when I'm finished :).

Happy Easter Weekend!


  1. I love the first photo! It's so "personal". :)

  2. Thanks! Yeah, Jess being a great mommy definitely helps here.

    We were also lucky to have the field to ourselves. Well, almost. There was a homeless person sleeping near that building, but I cloned him out of the final image :).