Wide angle lenses are great. They can cover a lot of territory. That can be important when you have to shoot in a limited space like indoors or when shooting large structures like bridges. Of course, every solution has it problems. The wider the focal length of the lens the greater the distortion (although there are distortions with telephoto settings as well, they are most pronounced with wide-angle settings).
The types of distortion lenses create vary:
*There is barrel distortion that causes straight lines to curve outwards in the center like ( )
*Pincushion distortion causes lines to curve inward towards the center like ) (
*Convergence causes lines to appear that they converge as they get further away like railroad tracks, like / \.
For most digital cameras, the wider the lens focal-length setting the greater the distortion. These distortions can be interesting, but more often they are cause enough to discard images or not use your wide angle settings as often as you would like.
There are a number of ways to deal with this. If you are shooting with an SLR you can purchase a very expensive wide-angle lens that does not distort or for architecture you can purchase one of the special lenses that allows the user to shift the image before capture. For the rest of us (and particularly those of us with digital cameras without an interchangeable lens) there is LensDoc from Andromeda Software. This Photoshop plugin presents the user with a simple-to-use interface that easily and quickly corrects these distortions and gives your images the look of being captured with a much more expensive lens.
Installation is a simple matter of running the executable which searches out your installation of Photoshop and then allows you to verify its location. Once that is done, all the filters are installed into the filters folder.
The LensDoc interface is quite simple to learn and use (I corrected my first image without reading the instructions). Follow the red numbers I have added to the LensDoc interface above (condensed to fit here) as I go through a distortion fix:
After opening the image to be adjusted in Photoshop, choose "Filters/Andromeda/LensDoc." When the window opens, be sure you are in "Novice Mode" (selectable at the bottom of the interface), then:
1) Select your lens type (for most this would be "Generic lens") and click on "Fix Distortion." There are specific lenses from which you can choose, but the list is limited and my camera was not included. Not to worry. According to Andromeda, the generic selection was derived from the testing of over 100 lens and focal length settings, and I must say it appears that they have hit it pretty much dead-on.
2) Select which of the sets of "targets" you are going to use. The best results will be had using both the green and yellow set. There is no difference between them, they are just color coded so as not to be confused on the interface.
3) Align the targets along what should have been a straight line. This could be anything that should be straight but isn't such as the edge of a building, a row of bricks, or the trunk of a tree. Try to pick something as near the edge of the image as possible. Note the target next to the number "3." The red rectangle around the target signifies the area which is being viewed in...
4) ...the magnified window. This gives the user a precise view of where you are placing the target. Holding down the Ctrl key puts LensDoc into fine-adjustment mode which makes pixel-level alignment easy. When in the fine-adjustment mode, the target in the magnified window automatically re-centers so you don't have to worry about it going out of view no matter how far you move it.
5) When you are done setting the targets, hit the "Correct" button and the image is "un-distorted' so that the lines are now straight instead of being curved. If you don't like the way it worked, hit the "Revert" button, readjust the targets and try again.
If you get stuck or forget how something works, just hold your cursor over the area of the interface in question and a tip will be displayed in the window on the bottom of the interface.
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Although sample pictures were included on the LensDoc CD I received, I always use my own images. To the right, the top, distorted image is the side of my laser printer taken with as wide of a lens setting as I could muster (28mm). It is obviously suffering barrel distortion as well as being misaligned. It took about one minute (fifty-two seconds to be exact) to open the image in the LensDoc filter, place both sets of targets, and correct the barrel distortion.
The next adjustment I applied to the image in LensDoc was rotational correction. Rotational adjustment rotates an image until a chosen line is vertical or horizontal in the image (user's choice). To make this adjustment, there are a pair of targets. Place them along a line that should be perpendicular then hit one of the two arrows that represent vertical or horizontal and the image is rotated and cropped. Rotational correction is really not that big of a deal as this can be easily accomplished in Photoshop but as long as you have the window open, might as well make use of it. The application auto-crops, and although this feature can be turned off, unless you have some special need, you should find that the cropping done by LensDoc is much as you would have done manually.
The bottom image shows the ability of LensDoc to effectively deal with some severe distortion. The lines on the side of the printer are very parallel and look like they were taken with either a very expensive lens or from some greater distance than the twelve of fourteen inches I used.
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The perspective correction is a very handy tool. Although this can also be accomplished in Photoshop without special filters as well, LensDoc makes it a fast, easy, and accurate task. This is a "keystone" correction (which is sort of half of a barrel distortion), handy for things like a picture of a building taken at ground level looking upwards. A wide angle lens makes the building look as if the building is shrinking and leaning over as it gets further away from the camera. This adjustment takes an additional twenty seconds or so- quick and easy.
It works the same way as the distortion adjustment. The difference is that in this case the targets are two pairs instead of being two sets of three- other than that, you pretty much already know how to do it from reading this far-place the targets and hit the button. Here you see I have been able to "straighten" the two palm trees showing the power of the perspective adjustment as well as the fact that LensDoc is effective on more than just buildings.
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Once you have finished making all your adjustments in the LensDoc window, hit the check mark in the lower right corner to
apply the changes to your image. The interface closes and the image in Photoshop is updated.
For the advanced user, LensDoc also has an Expert mode. This powerful tool allows greater manual control over the amount of correction applied using slider controls to fine-tune the adjustments. The most powerful function in the Expert mode is the ability to save a setting for a specific lens. You can take a set of images of a subject with very square lines at various focal lengths, manually make your adjustments in LensDoc, and save the settings under various names (for the different focal length used in each shot, such as @quot;Canon Zoom 24mm@quot;). After they are saved they are easily applied in the future. Why bother? There are times when an image contains few if any straight lines, not giving the photographer anything on which to place the LensDoc targets. A saved profile can be applied without using the targets at all. Even though most users will find the generic settings sufficient for most images, the Expert mode allows the filter to be more useful and less likely to be outdated.
Make sure you spend some time with the PDF manual. It is well written and organized, containing lots of helpful information to assist you in getting the most out of LensDoc. It also contains tutorials that go along with the included sample images.
CONCLUSION
I tried to fool LensDoc by moving the alignment squares out of order (I switched the left green target with the center green target) but it didn't phase LensDoc at all. This filter is fairly well thought out and simple to use. You will probably have little or no problem using LensDoc. I did find that if you have placed a target too near the edge of an image, after the adjustment has been applied the target might move out of the window. The only way to get it back would be to hit the revert button and place the target further away from the edge. This is covered in the manual, but it is a minor problem as you will usually find the first adjustment is correct and acceptable, and the missing target will not be needed again for that adjustment.
Other than that, the only other problem I found was that if you have finished adjusting an image and you just click the "X" to close the LensDoc window, LensDoc will close but the changes you made to the image are discarded. You are not presented with any "Discard changes?" warning window. Your work is lost and you go back into Photoshop with your image as you left it. To save the changes you must hit the check mark in the lower-right-hand corner.
The downloadable version of LensDoc is currently available for $69 for Mac and Windows boxes directly from the Andromeda website. That might seem like a lot of money to some folks to spend on one filter for Photoshop, but compared to the cost of a single, high-quality wide-angle lens (which can cost ten times that in some cases), it's a bargain. At the website you can see a demo of before and after shots, but my images above should be sufficient proof to convince you.
If you find yourself taking a lot of wide angle pictures whether with a digital camera or scanned images from film, and then wondering what to do with the trees that all lean towards the center of your pictures or how to deal with the buildings that look like over-inflated balloons, then LensDoc might be the solution you have been seeking. If LensDoc looks like something you can use but you are still not sure, download the trial version at the Andromeda website and see for yourself. While you are there check out their other unique filters for PhotoShop.
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