The accurate rephotographer usually determines several facts before taking a new image. An important starting point is the choice of the older image. To show continuity between the two images, rephotographers usually include in the frame a building or other object which is present in the modern view. Some urban scenes change so much that the original buildings shown have been completely obscured by subsequent skyscrapers, or have been demolished. A "then and now" photograph could be taken but there would be nothing in common to link the two images. The vantage point from which the original photographer took the view may have disappeared over the years, so the rephotographer has to choose an original view for which the vantage point is still accessible, or arrange to rent equipment to duplicate the original position of the
camera. Since modern cameras and lenses differ considerably from older in format, the rephotographer also has to take into account the field of view that the lens covers, and the
depth of field available. The best way to do this is to set up a
camera at the original viewpoint, at approximately the right season and time, and wait with the original view in hand, until the shadows reach the same positions relative to surrounding objects. If done with extreme accuracy it should be possible to place one image over the other, and see the edges of buildings match exactly. This type of rephotography can be seen in the
McCord Museum of Canadian History's virtual exhibition "Urban Life through Two Lenses". It shows the nineteenth-century views of Montreal by
William Notman, rephotographed by Andrzej Maciejewski in 2002. Another is Douglas Levere's project
New York Changing; here Levere rephotographed 114 of
Berenice Abbott's
Changing New York images. ==Mobile and computationally assisted digital rephotography==