Using a Tilt & Shift Lens for Distortion Correction

In a post last year I discussed using Tom Neimann’s PTLens program to correct for barrel, pincushion and perspective distortions in your architectural images. Tom’s program and Photoshop plug-in filter are nothing lens than amazing at correcting distortions that are easy to overlook with the naked eye. For most of us, using PTLens is definitely the way to go.

There is another way to correct for perspective distortions however, using a “Tilt & Shift” lens such as Canon’s brand new TS-E 24mm f/3.5L II. Since I’m a newbie at using a Tilt & Shift lens I’ll leave the complete explanation and demonstration of this unique lens’ features to Bryan Carnathan at The-Digital-Picture.com. Bryan does a much better job of explaining the technical aspects of this unique lens than I ever could.

I was fortunate enough to be able to try out this lens last year during a shoot in Goliad, Texas. I started by setting up my tripod and taking a few quick shots of Goliad’s historic courthouse using my EF 24-105mm zoom at 28mm.

As you can see in this image, the top of the courthouse seems to lean away from you and the vertical lines tend to converge. This is typical perspective distortion caused by the wide-angle lens being tilted up to capture the entire building in the frame.

Correcting this using a Tilt & Shift lens is very simple. You first level your camera on the tripod (which cuts off the top of the building in the frame) and then simply turn the shift knob until the building “shifts” down and into the frame as shown in the final image below. I finished this image very simply using Nik Software’s Silver Efex Pro plug-in filter. I find that most architectural images look best in black & white.

Historic Courthouse in Goliad, Texas
Copyright © 2009 Jeff Lynch Photography
Shot taken with a Canon EOS 5D Mark II set on aperture priority (Av) using an TS-E 24mm f/3.5L II lens tripod-mounted. The exposure was taken at 24mm, f/16 for 1/20th of a second at ISO 100 on Lexar Professional digital film. Post capture processing was done in Lightroom 2 and Photoshop CS4 using Nik Software’s Silver Efex Pro filter. Click on the image above for a larger version.

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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Using Canon’s Tilt & Shift Lenses for Distortion Correction

In a post last week I discussed using Tom Neimann’s PTLens program to correct for barrel, pincushion and perspective distortions in your architectural images. Tom’s program and Photoshop plug-in filter are nothing lens than amazing at correcting distortions that are easy to overlook with the naked eye. For most of us, using PTLens is definitely the way to go.

There is another way to correct for perspective distortions however, using a “Tilt & Shift” lens such as Canon’s brand new TS-E 24mm f/3.5L II. Since I’m a newbie at using a Tilt & Shift lens I’ll leave the complete explanation and demonstration of this unique lens’ features to Bryan Carnathan at The-Digital-Picture.com. Bryan does a much better job of explaining the technical aspects of this unique lens than I ever could.

I was fortunate enough to be able to try out this lens last Saturday during a shoot in Goliad, Texas. I started by setting up my tripod and taking a few quick shots of Goliad’s historic courthouse using my EF 24-105mm zoom at 28mm.

As you can see in this image, the top of the courthouse seems to lean away from you and the vertical lines tend to converge. This is typical perspective distortion caused by the wide-angle lens being tilted up to capture the entire building in the frame.

Correcting this using a Tilt & Shift lens is very simple. You first level your camera on the tripod (which cuts off the top of the building in the frame) and then simply turn the shift knob until the building “shifts” down and into the frame as shown in the final image below. I finished this image very simply using Nik Software’s Silver Efex Pro plug-in filter. I find that most architectural images look best in black & white.

Historic Courthouse in Goliad, Texas
Copyright © 2009 Jeff Lynch Photography
Shot taken with a Canon EOS 5D Mark II set on aperture priority (Av) using an TS-E 24mm f/3.5L II lens tripod-mounted. The exposure was taken at 24mm, f/16 for 1/20th of a second at ISO 100 on Lexar Professional digital film. Post capture processing was done in Lightroom 2 and Photoshop CS4 using Nik Software’s Silver Efex Pro filter. Click on the image above for a larger version.