Friday, June 12, 2009

Some HDR Techniques in Apple's Aperture

Here is a question I received about HDR which I will respond to for this week's post:

From Wayne: Here
is one(or several) for the blog. Some questions that have to do with
capturing your HDR images. I'm new to HDR methods as I have been
recently introduced but have not yet practiced them (as may be obvious
with the questions). My questions have to do with your "routine" HDR
methodology. Do you usually capture a landscape HDR series at your most
often used aperature of f22? How many exposures do you capture in your
typical bracket series, and what is your typical f-stop range:
fractional stops, 1 full stop to X (?) stops for each sequential
exposure? It all depends on the particular image and the lighting
conditions as changing variables I'm sure. How about sharing the data
for this particular image as an example (without revealing your trade
secrets of course)?

Oh and also, are you using any sort of add-in for processing or
merging the images or just using a Photoshop, Bridge, or Lightroom
"Merge to HDR". You may have addressed this before? I don't visit the
blog as often as I'd like!


Response: Hi Wayne, thanks for your question. The image Wayne is referring to is my new shot of Fly Geyser. I shot this in the very early morning light at sunrise and bracketed 5 shots at 1 stop difference (2 below, one at normal, and 2 above). I am finding that HDR works so well that a split ND filter is not as critical as it once was. (See my comments about split ND filters at this post). You can do HDR compositions with a smaller range of bracketed images, but 5 seems to work well. My favorite tool for doing HDR compositions is the Photomatix Plug in for Apple's Aperture. I can select the raw images I want to combine in Aperture, then tell Photomatix to align and combine them into one image with amazing tonal range. I can then "develop" that image in Aperture and export it to Photoshop for final sharpening & upsampling if needed. It is not a difficult process, but can be time consuming as my computer & photmatix process the large 39 megapixel files from the Hasselblad H3D. I personally like Photomatix plug in better than merge to HDR in photoshop, I just find it easier to use and easier to get better results from. I have to resist the temptation to "overcook" the image, I think they look better with a more subtle HDR treatment than the over the top treatments you can get if you really go for it. I have also found that the "tonal contrast" filter in Nik Color EFEX gives a little HDR like boost to most images, but again it is easy to overcook the image and it is good to fade back the filter. Nik filters can be used in Apple's Aperture and also in PS CS4 (an I think Lightroom although I do not use that). I am doing HDR on most images now, as long as there is not moving foliage it seems to work well. Problems arise in windy conditions and long exposures with moving clouds, etc. 

I have found that you can get better color and tonal range from an HDR image than from a single exposure no matter how good that initial capture is, as long as the conditions allow merging of images. Of course a tripod is critical to get images to properly align.