Spicewood Photography Blog

I need to write down my workflow, as the HDR process can get really annoying if you miss a step, either in the field (resulting in a botched picture) or in the digital workflow tools (resulting in hours of wasted time).

So here it is.  If you have additional steps or better ways of doing these things, please leave a comment!

BEFORE YOU START SHOOTING

1. Set the camera in aperture mode.  It is important that you use the same aperture for all shots in a series, as the depth of field must remain constant in order for the HDR software to properly process multiple exposures into one HDR image.
2. Set the ISO to 50 or 100, depending on the necessary exposure times.  Use the lowest ISO possible that will still take a crisp image.  If it is a windy day, or if your subject might move, use a higher ISO setting.  Never go above ISO 400, though, as the HDR process will amplify the noise from the camera.
3. Use a remote trigger with the camera.  If this is not possible, use the self-timer mode with a 10-second lag.  It is important that the camera be absolutely still in order to get crisp images.  The shutter release on the camera will cause a slight shudder, but that is generally not a problem.
4. Use a sturdy tripod for every shot.  Processing times are much shorter when the HDR software doesn’t need to re-align your images.  I suggest a carbon-fiber tripod, as it is lightweight in the field and solid as a rock even with the largest pro-body camera and heavy lenses.
5. Set the camera to take 5 to 7 bracketed exposures.  The higher the dynamic range of the scene, the more images you will need.  Keep the images within 1ev of each other to ensure smooth transitions in the final image
6. Put your lens in Manual Focus mode, and turn on Image Stabilization if available.  If y want your photos to be as crisp as possible, then don’t rely on the camera for focusing, use your eyes.  See the following section on how to get the best possible focus from a dSLR.
7. Always shoot in RAW mode.  RAW files store far more information on the scene, and can be manipulated to produce an accurate image +/- 1ev from the original.  These can be used if there is most of your images in a shot are unusable and you still want an HDR product from a single exposure.

TAKING THE SHOT

1. Compose the picture to your liking.
2. Focus the image using manual controls through the viewfinder or LCD (if your camera supports Live View).
3. Zoom in on the image using the LCD (not the lens).  Focus again manually, using the LCD.  Repeat with higher levels of magnification if available.
4. Wait for the light; wait for the wind to die down.
5. Take the shot using a remote trigger.
6. Review the images.  If the first image is too dark, consider shifting the exposures to the right (e.g. from [-3ev, +3ev] to [-2ev, +4ev]).  If the last image is too washed out, consider shifting the exposures to the left.  If both the first and last exposures are too black/washed out, then consider compressing bracketing to use 1/2ev stops instead of 1ev stops.

AT THE COMPUTER

1. Download the images into your favorite software (I use Apple’s Aperture).
2. Use auto-stacking of images if available, this makes it much easier to do the next step, especially if you take multiple images of a subject.
3. For each image, remove images that are too black or washed out, or do not add any additional detail to the image.  Combining images takes a long time unless you have a very, very fast machine.  I use a MacBook Pro and it takes several minutes per photo.
4. For each set of exposures, choose the best one and tag it with text like “Best Exposed Photo”.  This photo will be your reference photo, the one you will use to ensure that you are not going overboard with the HDR processing.
5. Create a new album with only the tagged photos in it.  This will be your reference set.
6. If your HDR software supports RAW files, by all means use them.  If not, you will need to export all of your photos to 16-bit uncompressed TIFF files.  This can take up a LOT of space.  WIth a 21MP camera each image is 120MB!  Time to invest in that external terabyte drive you have been thinking about.
7. Open up your HDR software.  I use Photomatix Pro because it has a great batch feature, although this feature only works well if you have the same number of exposures for each photo.  Note to Photomatix:  let me specify the batch exposure counts like this:  5, 5, 3, 7, 7, 7.  Or better yet, give me a really nice GUI that lets me set different parameters for each subset (each set of exposures).
8. Create HDR masters in OpenEXR format.  I prefer OpenEXR, but you could go with the HDR file format as well.  There are several great arguments for both formats on the web.  Note that there several settings that you can use when creating your EXR masters that help with things like background/subject movement and such.  Because I use a tripod and remote trigger, my images are almost always perfectly aligned, so I don’t have to do any repositioning.  The one exception would be if I am shooting water that has ripples.  If you don’t turn on the background movement feature the water will look really strange.  I don’t apply tone curves, so that option is left unchecked as well.  Reduce noise/reduce chromatic aberration might be useful if your camera does not handle blacks well.  Again, I generally don’t turn any of those on, and if you shoot at low ISO, you shouldn’t need them.
9. For each EXR master, you will need to do a tone mapping.  This is where those master images are needed.  Modify the tone mapping parameters until you manage to get a natural color balance.  This is different for almost every picture, and can take a significant amount of time.
10. Save your images to 16-bit TIFF images, and make sure to tell the program what ICC printer profile you will be using to print.

That’s about it.  Some thoughts on the process:

Creating beautiful, accurate HDR images is extremely time consuming.  As such, you might want to consider taking fewer pictures and spending a lot more time on each one.  Some people use digital cameras as a crutch, taking dozens of pictures in the hopes that one will come out well.  In my experience this just is not true.  Spend as much time as it takes to get the right angle and wait for the light, and you will seldom be disappointed with the results.

Pay special attention to the weather forecast the day before the shoot.  If it is going to be windy, you might want to concentrate on very wide-angle shots, or shots of rock formations!  Definitely don’t go out to do work in a forest.