Archaeological Photography – Photographing Buildings

Nearly everyone is familiar with the variety of lenses available for cameras.  You might not know what they all do but you probably have a general understanding that by twisting them you can change the focus and depending on the type of lens this can change drastically.  But have you ever seen a lens that flips to the right?  Today in class we were introduced to two lenses: the shift lens and the filter lens.  This post will talk about both.

Have you ever tried to capture a building from close range?  To do so you most likely had to tilt the camera up at an angle to get all of it.  But in doing so, you take the parallel sides of the building and put them in perspective.  This ends up with a photo of the sides of the building narrowing.  There is nothing wrong with perspective, but what if you want to keep the sides from narrowing and you just can’t (for lack of space) back up far enough to get the whole building in?  If you have a shift lens this is no longer a problem.

The Cone of Light in normal lenses at infinity fills up the size of the film.  However, the Cone of Light that comes through the aperture of a shift lens is larger than the film, this allows for the lens to shift and the camera to then be closer to the larger object.

It really is something amazing!

There are some cameras that even have a way for the film to shift which creates even more dramatic difference allowing the camera to be even closer.  These cameras do not have solid bodies like the cameras most people (including me) are used to using.  They have soft bodies.  We were told that the bellow bag body was preferable over the cardboard “accordion” bellows because the cardboard tended to resist the shift and distorted the photo in an unsatisfactory way.

One other trick on this tilt and shift camera frame allowed you to be even closer still to the building.  This feature is the tilt of the lens after the shift.  The lens is shifted up, the film is shifted down, and then the lens is tilted up but the film is left perpendicular to the ground.  Naturally this would allow for more building at closer range to be viewed by the lens but as the lens was no longer parallel to the film there would be a “depth of film” problem (“depth of focus” deals with the lens angle but “depth of film” only occurs in this situation where the lens is not parallel to the film).  To solve this problem (where only a thin line across the film would be in focus and the top and bottom of the film would be out of focus) a longer exposure was needed (similar to the solution in the “depth of focus” problem with the lens we learned about earlier in the term).

We went out into the “Main Quad” and shot a few different buildings at such a close range that without the shift only a small portion of the building could be seen.  We put the cameras on the tripods, attached the lenses and were ready to shoot when the professor informed us that in order for the building to “squared” in the photo we needed to square and level the camera.  We made the adjustments and shot the photos.  It was fun and next week we will work in the dark room so I can report on the photos we have been taking, including these and let you know how it went.

The other type of lens we used was the filter lens.  It was a normal lens in all respects except that it had an extra “ring” that could be turned to add either a “yellow” or an “orange” filter.  (There are other filters available such as red, blue, green, etc.)  A filter lens is useful for taking black and white (B&W) photos.  Filters allow for more contrast in pictures.

If you ever have taken a B&W picture of landscape chances are the sky had a washed out look to it in the B&W photo.  The reason for this is that the blue is not being picked up by the film.  Or if you have seen early 19^th century photos you probably noticed that the people looked ashen.  This was because the red in those early films wasn’t picked up as well.  The right filter would have helped in both cases.

To correct these problems, use a filter to “filter” out certain colors that you want to contrast.  If you are taking pictures of fall leaves, or example, choose a filter where one of the colors of the leaves (red or yellow) is also the color of the filter.  You will be happy with the sharp contrast that results.  Again, we will develop these pictures next week so I will report on the results then.