Photoshop's Free Transform

Since I have a particular fondness for photographing lighthouses, old barns, covered bridges and city scapes (among other things), I am often faced with perspective control issues, particularly when using a wide angle lens. The image below of the Watch Hill Lighthouse in Rhode Island is a rather dramatic representation of what happens when one points a wide angle lens above the horizontal horizon, ie, making vertical lines go out of parallel.  At this particular spot, there was not a lot of room between the lighthouse and the ocean so that the only options I had was  to either use a wide angle lens to capture all of the buildings here a Canon 16-35mm zoom  at 16mm, or use a shorter lens, like a 24mm tilt/shift lens, take several images and blend them together. To help with these types of perspective distortions both Nikon and Canon sell tilt/shift lenses in several different focal lengths. Canon has the largest selection with shift lenses coming in 16mm, 24mm, 45mm and 90mm. To further the options for a Canon shooter, one can also affix the Canon 1.4 extender to these lenses creating quite a significant selection of focal lengths. But if one chooses to use a different brand of camera or different format, there are not a lot of hardware options available to help. Even if one were to carry and use these  lenses, there is no guarantee that the lens will totally correct perspective issues.  Here is an image of the Nobska Point Lighthouse where the situation is similar to Watch Hill, the lighthouse and keepers house is on the top of a hill with very little room between the hill and the bank. For this image, I used a Canon 24mm tilt/shift lens and I was standing on the top of a guard rail.  The lens corrected the vertical lines so they are parallel, but that does not mean there isn't distortion to the vertical items off the center point of the lens.Fortunately Adobe and other software vendors provide perspective correction features to their software to help with this problem. Adobe's Bridge, Lightroom and Photoshop have lens correction features generally under their Lens Correction/Transform section. However, there are also some issues that one has to work around with using these solutions as the next two images illustrates. The top image is of the Cape Code Light or otherwise known as the Highland Light taken with a Canon 16-35mm zoom at 17mm. The next image is a copy of the first correct in Lightroom's Transform section. Notice that one has to give up a real estate to correct the vertical perspective issue. The second is that these controls do not correct for the horizontal distortion that we saw in the Nobska Point lighthouse. Further, there may be cases, like in the Watch Hill image where there is not enough real estate to make an effective correction using this method or the correction needed is just too severe and is beyond the ability of the software to correct adequately.  Fortunately, there is in Photoshop a tool which I now use a lot to correct for these types of issues, called Free Transform and can be found under the Edit menu.Free Transform is the  rotate, scale, skew, distortion and perspective commands found under "Transform" all rolled up into one that allows the manipulation of a selection within the image or all of  the image. Below is the result of applying, first the skew correction and then the perspective correction. As you will notice from this image, using the Free Transform tool preserved almost all of the original real estate of the image as well as doing a better job of maintaining the horizontal emphasis. Using the "perspective tool" allowed me to correct distortion of the light tower thus giving the whole image a much more natural look. Adobe warns that using the Free Transform tool too much will cause the image to be less sharp, but in this and other images where I have used this technique, I have not noticed any decline in image sharpness.To adjust the Cape Code Light, my steps were as follows:

1. Create a duplicate layer, a necessity to use these tools.
2. Drag vertical vertical gudes and place at strategic places in the image
3. Make your selection, since I selected the whole image in this example, I did not create a layer mask.
4. Select Free Transform from the Edit Menu
5. While holding down the Command + Shift keys for the Mac (or  Ctrl+Shift for Windows) and grab each top corner and dragged it out away from the center until the vertical lines were parallel.
6. Because this process has a tendency to shrink the object in the image, sometimes one needs to stretch the object or image up. This is easily accomplished by releasing the key selection, grabbing the top center handle and dragging upward.
7. Apply and one is done with this step.
8. Because I also made a perspective adjustment, I selected the light tower and made another layer via copy as well as created a layer mask.
9. Make my selection again and select Free Transform.
10. While holding down the Option+Command+Shift keys, Mac (Ctrl+Alt+Shift, Windows) select the top or bottom corners and move them up and down to achieve your desired adjustment in keeping with the snap guides.
11. Use the brush on your mask to paint out the areas were the adjustment is a problem.
12. Done.

A little later, I will add a video of this process.To some up, having a tool like Free Transform saves having to carry around a lot of extra lenses and allows one to preserve the composition of the image and still make the necessary perspective adjustments for a desirable and more natural looking image. After getting used to this process, one can complete the adjustment in fairly rapid fashion, particularly if you use the snap guides.For a good discussion on the issues of wide angle lenses, specifically, and other lenses in general, visit Sean McHugh's web site, Cambridge in Color.