WHEN REALLY WIDE ISN'T WIDE ENOUGH

I recently had to shoot a new 26 story NYU dormitory building in the East Village of Manhattan. The building is located on a fairly narrow street and, as in most cases when shooting in Manhattan, one of the toughest things to do was to find a vantage point to shoot from. After a whole morning on the phone, I was able to track down the owner of the building across the street who eventually gave me permission to shoot from his roof. The roof was about one third as high as my subject and offered a far better vantage point than the street. This situation was further complicated by the fact that the building faces north and except for very early morning on a few days in summer it would never be fully illuminated on a sunny day. Oh, and the sidewalk was scheduled to be torn up in a few days so if I didn't shoot in the next few days we had no idea when everything would be ready to shoot again. Sounds fun doesn't it?

I made my way to the roof opposite my subject on an overcast morning. I still had the problem of fitting this tall building into the frame from such a close distance. The widest lens I have is the Sigma 12-24mm f/4.5-5.6 EX DG. I'll be the first to say that this lens is not the best optically but it comfortably covers a full-frame 35mm sensor with almost no distrotion and when the situation calls for it, this lens is just great. At 12mm the building barely fit but looked terrible (figure 1). This tight crop also didn't allow for enough room to straighten the perspective in Photoshop.

My solution was to use a technique I've used many times - stitching. Most people only think of doing this with panoramic landscapes but I find it can be useful in many different situations, including building exteriors. I shot the building in sections using a longer focal length lens and was careful to make sure I had plenty of overlap from one frame to the next. I'll usually try a few different variations in focal length and amount of overlap just to make sure I'll get images that will stitch together well. In this case I chose 4 images to combine (figure 2).

The stitching capability of Photoshop in later CS versions (located under: File -> Automate -> Photomerge...) has been, in my view, one of the most improved features. Photomerge has been around for a while but until recently it did a pathetic job of combining images together. Now it's pretty amazing what it can do. You can choose files to combine from a folder on your hard drive or select images open in Photoshop as long as the images have been saved. You then select the type of layout from the menu on the left (figure 3). Auto usually does a good job but if you aren't happy with the results I would recommend using the Interactive Layout.

As good as Photoshop's Photomerge command has become, there are still better options for merging images. On certain images you can have areas where the stitching still doesn't really quite work in Photoshop. You need to review the stitched file carefully to look for problem areas (see figure 4). The best software I've found for stitching files is an application called Autopano Pro by a Kolor, a french software developer.

The advantage of Autopano Pro, besides just usually doing a better job stitching, is that it has extensive editing capabilities before the final stitched file is generated. You can specify the center point of the image and adjust for vertical perspective. I don't usually do any levels adjustments or color corrections in Autopano Pro although there are options for doing so. It's important to note that for this type of stitching you should make sure your projection is set to "planar" (see figure 5) this will keep your lines straight.

After Autopano Pro has rendered the stitched file (this can take a while depending on the file size) I'll go back into Photoshop to do all the cropping, levels and curves adjustments, retouching etc. The final image is one that I really don't think could be created with a single shot from such a close distance (figure 6). Even if you can get a good shot of a building or an object without stitching, you may want to use this technique on the rare occasion that you need a REALLY high resolution file. You might be doing a gigantic, wall sized print or you may want the ability to zoom way in on an image - in either case you can use this technique to increase the resolution of your camera almost indefinitely (the more segments you shoot, the higher the resolution file you'll have.) It's important to note that you can also use this approach with film, just stitch the scanned images together as you would the digital files.