PC World's Digital Focus: Wide-Angle Tips and Tricks

Feature: Eliminating Wide-Angle Distortion

Wide-angle lenses are great for packing more into a picture and for capturing images with a slightly unusual perspective. I frequently use wide-angle lenses to take landscape photos, and they also come in handy for pictures of large groups of people. If your digital camera's wide-angle setting isn't particularly wide, you can always buy a screw-on or snap-on wide-angle adapter for your camera. But wide-angle lenses have a downside: They sometimes introduce unwanted distortion into your photo. Of course, the nice part about having a digital camera is that you can easily remove that distortion digitally.

Barrel Distortion

The process behind this unwanted bending is called barrel distortion. A wide-angle lens distorts the image by curving straight lines. You can end up with a picture that doesn't look quite right because the walls of the room are warped like the reflection in a funhouse mirror. Check out the same image with (on the left) and without barrel distortion.

All wide-angle lenses create some amount of barrel distortion, though the effect can vary depending upon the lens. The wider the lens, the more pronounced the effect will usually be. A fisheye lens, in fact, is just a super-wide-angle lens that has the ultimate in barrel distortion. Sometimes you'll want that effect. At other times, you may want to avoid creating funhouse photos.

Minimizing the Distortion

One way to avoid barrel distortion is to simply avoid taking your wide-angle lens all the way to the limit. If it's part of a zoom lens, just back off before you get to the extreme end of the lens' range. If you're using a wide-angle adapter, be careful not to combine too much wide-angle in the camera's built-in zoom with the wide-angle lens attachment. You should be able to see the distortion in the viewfinder if you pay attention, though I know from personal experience that sometimes it creeps in unnoticed until you review the pictures on the computer screen. That's because a little curvature is hard to see in a tiny display, but it's quite apparent on a large 17-inch monitor.

So there's my first bit of advice: To avoid wide-angle distortion, don't shoot in wide-angle mode. I know what you're saying, though--that's a cheap tip, kind of like the old doctor joke that ends in "Don't do that." Fair enough.

You can also disguise barrel distortion. If you're shooting in extreme wide angle, avoid shooting pictures of subjects that have very straight lines you rarely find in nature, like walls, rails, skyscrapers, and other manufactured objects. Most natural scenes, like landscapes, flowers, and animals rebound from barrel distortion much more elegantly.

Splice and Dice

You can avoid using a wide-angle lens entirely by taking several individual pictures with a normal lens and splicing them together afterwards. Consider a shot of the Grand Canyon; you could get the whole thing in a single, massively wide photo, or take three or four separate pictures that would be free of distortion. When you get home, use a panorama stitching program to "glue" the images together into a single photo.

Straighten It Digitally

If you do end up with some photos that have obvious wide-angle distortion, all is not lost. There are several programs available that can help you to reduce or even eliminate curvature in digital photos that were taken with a wide-angle lens. These programs may ask you to vary the lens distortion by some seemingly arbitrary value (a little experimentation and judicious use of the Undo button works wonders) or to simply identify the lines in the photograph, like a wall or horizon, that should be straight. It then "unbends" those lines, hopefully correcting the entire image in the process.

If you received software with your digital camera, check out its collection of filters for an editing tool that will allow you to straighten out your image. Unfortunately, neither PhotoShop nor Paint Shop Pro comes with the necessary tools, but you can install optional add-in filters that will do the job. One effective utility that corrects for barrel distortion can be found in Panorama Tools.

Panorama Tools is free, but it's not the simplest program I've ever tried to use. If you are willing to invest $89, Andromeda Software's LensDoc is a much more user friendly alternative (check out Dave's Favorites for more on LensDoc).

Dave's Favorites: LensDoc

Barrel distortion really bugs me. If I know that a line in a photograph--like the wall of a skyscraper or the horizon--is supposed to be straight, even a slight bow ruins the entire shot for me. That's why I adore LensDoc from Andromeda Software. I've tried other programs that try to correct for a wide-angle lens' barrel distortion, but I keep coming back to LensDoc.

A standard PhotoShop Plug-In, LensDoc runs inside any image editor that recognizes Plug-Ins. I routinely use it in Paint Shop Pro, for instance, and it works exactly the same there as it does in PhotoShop. To use it, simply load an image and invoke LensDoc from the Plug-In Filters menu.

The genius of LensDoc is that instead of making you enter meaningless numbers into a dialog box in a frustrating game of trial and error, you simply drag a trio of dots over what should be a straight line in the image. Then just click a button and the image is instantly corrected, with little, if any, unwanted distortion.

LensDoc sells for $89 and is available from Andromeda Software. It's certainly expensive if you only need to fix one or two pictures, but if you consider it a long-term investment for correcting a lifetime of future warped photos, it's definitely worth the money.

Q&A: Capturing Video From a VCR

I am planning to purchase a new computer with Windows XP. I hope to copy short snips of video from my VCR, then display those clips from within PowerPoint. Will Windows XP let me do this, or will I have to find another product to accomplish this goal?

--Tony Santos, Wilmington, Delaware

Based on the number of video questions I get these days, I'd say that desktop video is gaining critical mass. Everyone seems to be interested in making digital videos, and that's very exciting. Unfortunately, it's still not quite as easy to do as digital photography. Case in point: capturing video from a VCR.

If you had a DV camcorder, a new PC with Windows XP would be a complete solution for making short, low-res video clips for a PowerPoint presentation. But your VCR doesn't have an IEEE-1394 port, so XP won't be able to import the video. Instead, you'll need to get a video capture device for your new PC that can grab video ported in via good-old composite video cables.

You have two choices. Some new PCs actually come with S-Video-style video-in connectors right on the graphics board. The PC will probably also come with a simple video capture program to take advantage of that special graphics board. If you find a PC like that, your prayers are answered. Otherwise, you should grab one of the many analog video capture systems that are out there. In particular, you might want to investigate the $300 Dazzle Digital Video Creator II.

This product features a video port hub that sits outside your PC, so you don't have to crane your neck and reach behind your PC every time you want to connect a VCR or camcorder.

Hot Pic of the Week

Get published, get famous! Each week, we select our favorite reader-submitted photo based on creativity, originality, and technique. Every month, the best of the weekly winners gets a prize valued at between $10 and $100.

A gentle reminder, folks: We disqualify some really wonderful pictures every week because the submissions aren't following the rules. In your e-mail message be sure to include everything we ask for, including a description of your picture and your complete contact information, or your entry is wasted!

Here's how to enter:

Send us your photograph in JPEG format at a resolution no higher than 640 by 480 pixels to hotpic@pcworld.com. Entries at higher resolutions will be immediately disqualified. If necessary, use an image editing program to reduce the file size of your image before e-mailing it to us. Include the title of your photo along with a short description and how you photographed it. Don't forget to send your name, e-mail address, and postal address. Before entering, please read the full description of the contest rules and regs.

This week's Hot Pic: Wynther, by Donna Alexander, Cambridge, Massachusetts

Donna took this charming portrait of Wynther in her backyard during a reflective moment as the little girl responded to the sound of chirping birds in the tree above her. Donna used a Toshiba digital camera set on automatic exposure.

January's Hot Pic of the Month

Each month we choose one of our weekly winners to be the Hot Pic of the Month. For this first winner of 2002, we chose the striking digital composite Flying Gull, by Howard Schiff of Roslyn, New York. Howard has won a PC World CD case. Congratulations to all the other weekly winners, too--the entries keep getting better and better!

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