Example of digital perspective control
The top image has an unnatural slant to the building because a wide-angle lens was used that was tilted up. They manufacture expensive "tilt-shift" lenses to deal with this, but Photoshop can do the same thing (as can a good enlarger or a larger format view camera). I learned how to do this using a recent article in Popular Photography
Original Image:
(Minolta X-700, Minolta MD 24mm, Fuji Velvia, polarizer filter, exposure unrecorded. Scanned with Polaroid Sprintscan 4000)
After Photoshop:
