May 24, 2004: Pleasant Avenue / Distortion
I prefer to take pictures of architecture with my Canon Digital Rebel/Tilt-Shift lens camera, because it can do 30s exposures up to f22, and the TS lens eliminates most perspective distortion. Sometimes it's impractical to carry such a large camera, such as this past Thursday, when Mike and I went up to Pleasant Avenue in East Harlem (home of Rao's restaurant and Sonny's fight with Carlo in the Godfather). It's pretty safe up there- so I wasn't worried about theft- but there was a chance of rain and I didn't want to damage the TS lens. Instead, I took my little Canon G2 and a 2' tripod. The shots it takes aren't as good as the Digital Rebel- it's only 4mp, and the longest exposure it can do is 15s on f8. Also, because it doesn't have a TS lens, many of the pictures come out with distortion.
As Red pointed out, there are two types of distortion: barrel distortion from lens imperfections (straight lines show up as curved lines at the edge of the image, particularly when you are at full wide angle), and perspective distortion from tilting the camera back to get the top of the building (lines seem to be intersecting, or the building appears to be leaning backwards). Short of using my real camera, the only way to correct this stuff is in Photoshop. I've generally avoided it before, but the crop tool has a perspective check box that allows you to correct most perspective distortion. It's not perfect, and there is some stuff you can't really fix, but it does a rough approximation of a Tilt-Shift image. Since my camera only has a little bit of barrel distortion, I've just left that alone- but if you want to correct it on your wide angle pictures, a good guide can be found at Digital Photography Review.
Before I read your text I thought that there was something funky with perspective. Now I understand that it was Photoshop mimicking a T/S lens. I don't think I'd want to mess too much with that. Some of the pics looks like there is convergence happening in two different directions at the same time. It's the window frames which keep throwing me off in a couple shots. Some vertical lines lean one way and others lean the other way. Wacky.