Photography and Art

Sunday, May 24, 2009

Correct Lens Distortion

I'm a big fan of raw processing. I use Lightroom to process raw photographs from both my cameras (a Canon 5d and a Panasonic DMC-LX2) because it gives me lots of advantages:

  • White balance Correction. More often than not, the camera gets the white balance wrong. Sometimes the adjustment is minor, but other times (e.g. indoors with the Panasonic), the adjustment is quite drastic.
  • Recovery of blown highlights. I try to expose to the right when I shoot in order to maintain as much shadow detail as possible. Sometimes, I'll blow the highlights out slightly. Not to worry, with Lightroom I can recover these blown highlights while retaining the detail captured in the shadows.
  • Adjustments (e.g. curves) done in 12+ bits to preserve smoothness of the curves.
  • Production of finished photos using lossless compression - important if you are going to edit the photo again and again.
However, some camera manufacturers are packing more and more processing into the camera itself. This is due to competitive pressure as well as the continual improvement in the raw processing horspower available to camera manufacturers. Most "normal" digital cameras are capable of doing white balance adjustment, color correction, saturation adjustments, sharpening and Jpeg compression in the camera. But, now we're starting to see cameras, such as the Panasonic DMC-TZ5, correct for lens distortion.

This raises a bit of a dilemma. Should you give up the advantages of external raw processing in order to avail yourself of in-camera lens distortion?

Fortunately, help is near at hand. There are several software packages that you can download to help you correct lens distortion in your camera. DxO Pro is certainly a leading candidate, but it is not cheap! A less expensive option is PTlens from Thomas Niemann. This Photoshop plug-in has profiles for all my Canon lenses as well as for my fixed lens Panasonic DMC-LX2. Here's a review of the software on the Digital Outback Photo site.

The best news is that the software can be evaluated for free and only costs $25 to license. In this day and age, that is a bargoon!

Here's an example of a photo corrected with PTLens. The photo was taken from the Top of the Rock (top of the Rockefeller Center in New York) with my Canon 5d and the 24-105 L lens at its widest (24mm). There is a lot of perspective distortion:

I edited the photo in Lightroom to correct the exposure and then exported it to Photoshop with Lightroom edits intact. While in Photoshop, I ran Noise Ninja to remove noise, then used smart sharpen to do some sharpening and ran PTLens to correct the distortion. My final adjustment was to run the Velvia Vision action to add some local contrast and more saturation.

Here's the result:

As you can see, PTLens has corrected the perspective distortion and vignetting. It has also automatically corrected for my lens' pincushion or barrel distortion at the 24mm mark.

The software is amazingly intuitive and does a splendid job of fixing lens issues.

Photoshop CS4 has a very good lens distortion filter, but I prefer PTLens because it runs as a Lightroom external editor and quite often I prefer to stay in Lightroom and edit my photos.

Friday, May 15, 2009

Windows 7

This is normally a blog about photography, but photographers in the digital age spend an inordinate amount of time on their computers, so occasionally it makes sense to talk about new software tools that make our jobs easier. I'm happy to report that Windows 7 is one of those tools. 

At the risk of insulting Microsoft, the best operating system for my PC is one that I don't notice. The less intrusive an operating system is, the better I like it. My PC is a tool that I use for my job and photography and Windows 7 is a great operating system because it fades quickly into the background and simplifies my life.

I've been running the Windows 7 release candidate now for a week. I've rolled it out from a slow single core Pentium machine that acts primarily as a printer attachment on the network to my main desktop (four Intel cores) and now my laptop (two Intel cores). Prior to that, these three machines were running Vista with mixed success. 

Vista was a disaster for the old printer machine because it needed more memory than I could install on the box. The old Pentium had the max 2 gigs of memory, but Vista thrashed around and couldn't run Photoshop or Lightroom without the disk light going non-stop, indicating that memory was swapping in and out constantly. Response time was abysmal. It took forever to boot. I managed to make the situation workable by plugging in a 4 GB flash card and using it for swap space - Vista still thrashed about, but response times were manageable.

Under Windows 7, the old machine's disk light still goes a fair bit after booting, but eventually it settles down to a nice equilibrium, indicating that the Windows 7 memory footprint is smaller than Vista. Switching from application to application is really snappy. Boot times are definitely much lower. My old computer has come back from the dead with Windows 7.

For my other machines, each with 3 GB of memory, Vista was not really a performance issue. The quad core desktop handled Vista pretty well and the laptop was a bit more sluggish than under XP, but tolerable. Windows 7 has really helped snap up the laptop and is even helps the faster desktop.

It's interesting to read the PC World article that claims that Windows 7 is not much faster than Vista. I think they totally miss the point. It is absolutely true that applications like Lightroom and Photoshop run almost exactly the same speed on my main editing machine on both operating systems. But, neither one runs well on Vista on my older, slower machine with less memory. With Windows 7, they run tolerably well. Windows 7 is much better from a speed point of view because it just seems snappier. Going back to my original premise, you don't notice an operating system that switches back and forth from one window to another without delay. And that's a good thing!

The other thing I really like about Windows 7 is the simplified user interface. The bottom task bar can now be used for all your commonly used software and it works just like (surprise!) MacOS. All your common apps are arranged across the bottom of the screen. When an application is running, it gets a little box drawn around it (as opposed to the little MacOS divot). When you hover your mouse over the running application, it gives you a little screen snapshot (or more if you have two or more instances running). This is really nice.

But, going back to the theme of this post, Windows 7 is really good because it doesn't annoy you. Applications switch back and forth quickly. It boots quickly. After you put your laptop to sleep, it wakes up quickly without a bunch of thrashing around. The interface is simple and elegant. I've experienced almost zero bugs with the release candidate version. Installation was fast and simple - you don't even have to watch over it. Once you've answered a couple of questions, it installs all by itself.

I think Microsoft has a winner on its hands here! Finally.

Thursday, May 7, 2009

Frustrations of Photography

I've been doing a lot of reading lately about successful landscape photographers. The common themes include an all-absorbing love of nature as well as a willingness to do what it takes to get wonderful image. Here are some examples:

  • 1st place winner of Canon's In the Parks photo contest Robert Blanchard tells Shutterbug magazine that he "positioned myself at "bird's eye" view by lying prone in the mud with my tripod legs extended out flat". The resulting image of a heron in the water is lovely.
  • In the same issue, second place winner Brian Rueb risked a soaking in icy water by going to the edge of thin ice to capture a reflection of El Capitan in Yosemite.
  • The December 2008 issue of Digital PhotoPro has several articles on modern masters. The thread that ties them together is the amount of hard work that they do to create their images.
I'm not averse to hard work. In fact, one of my nicer tree images was taken in a swamp during black fly season where I was in danger of being eaten alive before getting the shot.

Sometimes, however, despite hard work, things just don't work out. I'd been planning to do a shot of a lovely barn that I know of just as the full moon rises behind it. I'd planned the shot by going onto the Internet and finding the day that a nearly full moon rises in the early evening just prior to sunset. The choices were May 6th and May 7th. 

Yesterday, I headed home early from work, grabbed my camera and headed north to the barn. In the traffic, it was about a 2 hour drive. When I left work, the sun was out, but there were clouds on the horizon. As I drove north, the clouds steadily gained on me and by 6 o'clock, the sky was completely covered. I headed home with my tail between my legs.

I'll just have to go back to the drawing board and pick the next full moon evening.