http://shawnclover.com/2010/10/01/1906- ... nd-part-i/
After sifting through catalogs of library photos of the devastation of San Francisco’s 1906 earthquake, I picked out a variety of photos taken from April 18, 1906 to 1907 that I felt give a well-rounded depiction of what was going on in the city at the time.
Now comes the fun part. Where was the exact spot the photographer stood? What was the equivalent focal length of his camera’s lens combined with the film medium? How high off the ground was the camera? Where was the sun in the sky? Everything needs to be precise when layering two photos on top of each other. My original idea was to tear away a piece of the modern photo to expose the 1906 photo, but after playing around a bit, everything seemed more interesting when the two were softly blended together.