Canon’s Auto Exposure Bracketing Explained

Canon has made serious improvements in the Auto Exposure Bracketing in the EOS 50D / 60D / 7D and 5D2 although they still lack the ability to take more than three bracketed exposures at a time. Today, only the much more expensive EOS 1D Series cameras allow for more than three bracketed exposures. In these newer EOS models, Canon has combined Auto Exposure Bracketing with Exposure Compensation in a way that should make photographers working with HDR (high dynamic range) techniques very happy.

As you can see in this image, photographers can now use this feature to easily shoot a series of bracketed exposures covering the histogram from -4 EV to +4 EV in increments as fine as 1/3rd stop. For my own architectural HDR work I generally use the following series of nine exposures to provide the maximum dynamic range. I can take four continuous bursts of three bracketed exposures (I generally delete the three duplicate exposures) in less than 10 seconds.

Many of the latest EOS models have a new “function” button that can be set to display the EC/AEB settings as shown above. Once the EC/AEB settings are displayed I take the first set of three bracketed exposures with the camera set on continuous burst (high) with EC set at +2 EV. The three bracketed exposures take less than 1 second.

I then change the exposure compensation to +1 EV using the Quick Control Dial, hit the set button and take the next set of 3 bracketed exposures. Again, this takes less than 1 second. I continue this process two more times at -1 EV and -2 EV and end up with 12 exposures taken in less than 10 seconds. Its not as automated as using a Nikon D3 or D300 but it works fine for me.

EC Value  |  AEB Amount
+2 EV  |  +/- 2 EV = +4 EV, +2 EV, 0 EV
+1 EV  |  +/- 2 EV = +3 EV, +1 EV, -1 EV
-2 EV  |  +/- 2 EV = -4 EV, -2 EV, 0 EV
-1 EV  |   +/- 2 EV = -3 EV, -1 Ev, +1 EV

Results
-4 EV, -3 EV, -2 Ev, -1 EV, 0 EV, +1 EV, +2 EV, +3 EV, +4 EV

Do I really need nine exposures for my HDR work? Probably not, but I’ve yet to find an architectural situation where nine exposures didn’t adequately cover the entire dynamic range,  so for me this technique works perfectly. Its one more reason why the newer EOS cameras are a welcome upgrade from the previous models.

My basic HDR setup is fairly standard.
1) Camera on tripod, lens with AF on, IS off.
2) Set the AF point to ONE point, not “auto”.
3) Focus on the subject and set the lens’ AF to off (manual focus)
4) Take the bracketed exposures.
5) Review the histograms to make sure the entire dynamic range is covered.
6) Process in Photomatix Pro.

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No HDR Required

I seem to on a roll this week so I’ll stick my neck out again with another over the top proclamation; You don’t need no stinking HDR to obtain a well-balanced exposure! Boom! There it is. Let the flames begin. 😉

Wow, that was fun. Honestly though, you really can get a well balanced exposure even in bright sunlight. I took this shot last June during an early evening hike in Palo Duro Canyon State Park in the Texas panhandle. I was hiking to find some interesting subjects to shoot later in the evening when I came upon this grouping of rocks framing the canyon rim in the background.

I was facing almost due west and the sun was casting very harsh shadows onto the red dirt. This type of scene is well beyond the dynamic range of any DSLR sensor with the bright sky almost eight stops brighter than the shadows under the rocks. I knew if I had any chance of getting a decent exposure I would have to fool my camera’s light meter and even out the exposure in the scene. Where an HDR expert would take several shots at various exposures and blend them together in Photomatix, I wanted to see if it was possible to do the same “in camera”.

Hiking in Palo Duro Canyon – Canyon, Texas
Copyright © 2010 Jeff Lynch Photography
Shot taken with a Canon EOS 5D Mark II set on aperture (Av) priority using an EF 17-40mm f/4L USM lens tripod mounted. The exposure was taken at 31mm, f/16 for 1/20th of a second at ISO 100 with a Singh-Ray warming polarizer filter and 2-stop graduated neutral density filter. Post capture processing was done in Adobe’s Lightroom 3.

Click on the image above for a larger version.

View Location on Panoramio & Google Earth: Hiking in Palo Duro Canyon – Canyon, Texas

Incident or Spot Metering
My first step was to grab my Sekonic L-358 and meter the background, the rocks and the shadows to see just how far apart they were in exposure. Your Canon DSLR’s meter can also do this when used in “Partial” or “Spot” metering modes. If you try this in “Evaluative” mode your camera’s meter will most likely blow out the background completely.

Aperture Priority
I set my tripod mounted camera on Aperture (Av) priority at f/16 and took a quick shot using Spot Metering mode with no exposure compensation and no filters. I chose a single focus point in the shadow of the large rock to see how much detail I could capture. As I thought, the shadow detail was fine but the blue sky and white clouds were completely blown out.

Manual
Next I set my camera on Manual (M) with f/16 at 1/10th of a second shutter speed, again with no filters. Now, the blue sky came back a bit but the white clouds were still blown out and the shadows had darkened only a little. Now, we’re cooking!

Filters to the Rescue?
At this point I had pretty decent exposure of the rocks and shadows but the sky was still too bright. So I added a Singh-Ray circular polarizer to my lens and dialed in about half power by rotating the filter slowly until the clouds showed some detail. I also added a 2-stop, soft edge, graduated neutral density filter angled to match the slope of the canyon rim.

I adjusted both filters and my shutter speed until the blue sky darkened and the white clouds barely showed any detail. This resulted in an exposure of 1/20th at f/16 which evened out the light and dark areas in the shot with one exception. Anyone care to guess?

You’ve got it. The top of the large rock was bisected by the graduated ND filter and became much too dark for the image to look realistic. As one of my readers (and a friend I hope) from the Pacific Northwest points out, this is where graduated ND filters fall down on the job.

Finishing Your Image in “Post”
Luckily, this is where a program like Adobe Photoshop or Lightroom really shines. As you can see in the screenshot below, I used Lightroom 3’s “Adjustment Brush” to paint the top half of the large rock to increase the exposure, brightness and contrast until it matched the lower half.

Conclusions
Did I cheat to get this shot? That’s up to you to decide. I’m pleased with the results and very pleased that I could do it with 95% “in-camera” techniques and only 5% “post processing” techniques and I did it without resorting to HDR.

Does that mean that I’ll never use HDR techniques in my work? Not at all. Many of my best interior shots were created by blending several exposures together using Photomatix Pro. I may advocate creating images “in camera” but I’m also very pragmatic. I look at software (Lightroom, Photoshop, Photomotix) in the same manner that I look at hardware (camera, lenses, strobes). They are just tools, no different than a typewriter or a monkey wrench. Whatever it takes to get the job done!

Canon 50D – High Dynamic Range Photography

The new Canon EOS 50D is especially well suited for high dynamic range (HDR) photography with its 15.1 MP sensor, its Highlight Tone Priority mode and an array of very sharp lenses like the EF-S 10-22mm f/3.5-4.5 USM.

I wanted this image to display as much detail as possible in the church’s beautiful exterior clapboard siding and scalloped trim. Merging three exposures (-1.5 EV, 0 EV, +1.5 EV) and tone-mapping in Photomatix Pro brought out a lot of hidden detail and converting the image to grayscale in Lightroom finished it off very nicely.

Metering a bright white structure against a cloudy sky was a challenge for the camera’s meter so I took several bracketed sets using various levels of exposure compensation until I got just the right three histograms. Exposure compensation and auto-exposure bracketing can now be set using the same screen on the EOS 50D, allowing a quick check of the overall exposure when combining both as I had.

Catholic Church in Wallis, Texas
Copyright © 2008 Jeff Lynch Photography
Shots taken with a Canon EOS 50D tripod mounted, EF-S 10-22mm f/3.5-4.5 USM at 11mm, f/8 at ISO 200 on Lexar Professional (UDMA) digital film. All post capture processing was done in Photomatix Pro 3.1 and Lightroom 2. Click on the image above for a (much) larger version.

Two Views

I’ve really fallen in love with the incredible detail that results from tonemapping a multi-exposure HDR image. The two images shown here were created by merging seven different exposures that were taken using the techniques that John O’Connor explains in his Raindrops and Ferns-HDR post. The first image was converted to grayscale after tonemapping and the second was processed “normally” in Lightroom 2.

Shelter B&W
Copyright © 2008 Jeff Lynch Photography
Shots taken with a Canon 40D tripod mounted, EF-S 10-22mm f/3.5-4.5 USM at 10mm, f/11 at ISO 100 on SanDisk digital film. The HDR file was made from seven RAW images tone-mapped in Photomatix Pro. It was converted to grayscale in Lightroom 2 and finished in Noise Ninja. Click on the image above for a larger version.

Shelter
Copyright © 2008 Jeff Lynch Photography
Shots taken with a Canon 40D tripod mounted, EF-S 10-22mm f/3.5-4.5 USM at 10mm, f/11 at ISO 100 on SanDisk digital film. The HDR file was made from seven RAW images tone-mapped in Photomatix Pro. All other post capture processing was done in Lightroom 2 and Noise Ninja. Click on the image above for a larger version.

In the past few months of playing around with high dynamic range processing I’ve found that the secret to obtaining a really detailed HDR image is in eliminating any camera or subject movement “during and between each exposure”. This can be accomplished using the techniques that John explains or by using the High Speed HDR technique popularized by Uwe Steinmueller.

I’ve also found that (for me) Photomatix Pro 3.1 gives me the most realistic looking results and the lowest noise in my images. One final thing to remember is that almost every tonemapped image still needs some final “tweaking” in Lightroom or Photoshop to obtain the best results.

What Else Will That Lens Do?

I think I’m on a roll here so I’m gonna keep going.

One of the other neat little things that the Canon EF-S 10-22mm f/3.5-4.5 USM lens excels at is wide-angle high dynamic range photography. I believe the keys to a really cool HDR image are good color depth and incredible detail and this lens performs very well on both fronts.

I took this series of three images (shown here as a finished HDR image) at both the minimum focusing distance (about 10 inches) and the widest focal length (10mm) for this zoom. If you click on the image below you can see the incredible detail in the texture of the wood and rocks captured by this lens.

Enjoy!

Wide-Angle HDR
Copyright © 2008 Jeff Lynch Photography
Shots taken with a Canon 40D tripod mounted, EF-S 10-22mm f/3.5-4.5 USM at 10mm, f/13 at ISO 100 on SanDisk digital film. The HDR file was made from three RAW images tone-mapped in Photomatix Pro. All other post capture processing was done in Lightroom 2 and Noise Ninja. Click on the image above for a larger version.

Really, Really Wide

If you’ve read yesterday’s post about the Canon EF-S 10-22mm f/3.5-4.5 USM lens the question you’re probably asking yourself is just how wide does that lens really go?

Here’s a pretty good example from Monday’s visit to the Monument Hill State Historic Site. I took this shot (series of three shots converted into an HDR file) with my 40D tripod mounted and the lens at 10mm without a circular polarizer. Yes, that’s correct. NO circular polarizer!

To give you a better idea of just how much detail this lens captures, the tree just to my left was less than 3 feet away from me. The Colorado river seen in the center of the image is about 2 miles away and the bridge you see in the distance is over 6 miles away (as the crow flies).

If you click on the image below and look left of center above the horizon you can also make out the faint outline of the moon.

Not too bad for a “consumer grade” lens!

Really, Really Wide
Copyright © 2008 Jeff Lynch Photography
Shots taken with a Canon 40D tripod mounted, EF-S 10-22mm f/3.5-4.5 USM at 10mm, f/13 at ISO 100 on SanDisk digital film. The HDR file was made from three RAW images tone-mapped in Photomatix Pro. All other post capture processing was done in Lightroom 2 and Noise Ninja. Click on the image above for a larger version.

Black & White HDR Photography

Late last month I began experimenting with converting tonemapped HDR images into grayscale. I wanted to see how the extended shadow detail found in HDR images would look in B&W. I’ve found that tonemapped images produced from software such as Photomatix Pro almost mimic the grain found in B&W films such as Kodak’s TriX when they are converted to grayscale.

What do you think?

The Stables
Copyright © 2008 Jeff Lynch Photography Shot taken with a Canon 40D hand-held, EF-S 17-85mm f/4-5.6 IS USM at 17mm, f/11 at ISO 200 on SanDisk digital film. The HDR file was made from three RAW images tone-mapped in Photomatix Pro. All other processing was done in Lightroom 2 and Noise Ninja. Click on the image above for a larger version.

Autumn Comes to Southeast Texas

The cooler temperatures, low humidity and autumn colors have finally begun to arrive in southeast Texas and all I can say is “Thank God”. It’s been a hot, humid summer and with all the roof repair work due to Hurricane Ike, we sure could use a break.

This image was taken Monday at the Monument Hill State Park near La Grange, Texas. The colors had just started to change and the mid-morning sun gave the trees a wonderful glow. I decided to process this as an HDR image using Photomatix Pro to see how the colors would turn out. Not too bad for a walk in the park.

Falls Colors Just Beginning to Show
Copyright © 2008 Jeff Lynch Photography
Shots taken with a Canon 40D hand-held, EF-S 17-85mm f/4-5.6 IS USM at 28mm, f/19 at ISO 200 on SanDisk digital film. The HDR file was made from three RAW images tone-mapped in Photomatix Pro. All other post capture processing was done in Lightroom 2 and Noise Ninja. Click on the image above for a larger version.