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The relationship between an object in the foreground and an object in the background is called perspective.  Because telephoto lenses can compress the distance between a foreground and background object, and have a very small field of view (narrow picture angle), they can drastically alter our perspective in a photograph.  Even when the objects in a scene do not move, a photographer can use a wide angle lens to show a background object as distant and small, or a telephoto lens to show a background object as near and towering.  The lens used to take the picture can set the mood for the picture.

To set up this demonstration, I parked my truck in front of an old barn.  I left a good amount of distance between my truck and the barn, but my truck was never re-positioned for this series of photographs.  It remained in the exact same spot for all of the pictures.  Unlike the demonstration in Topic 3, my tripod was not kept in the same position.  I re-positioned the camera for each picture so that my truck was in the full frame of each photograph.  I had to stand closer to the truck with the wide angle lenses (wide picture angle), and kept moving further back as I increased my focal lengths (narrowed picture angle).  The pictures were taken from the same height in all cases.  By keeping my truck the same size in each picture, and changing focal lengths, you can see the dramatic effect that telephoto lenses have on the background object (in this case, the barn).

I couldn't get all the way down to the 12mm focal length, because I was practically on top of the truck as it was at 15mm.  At 550mm I was on the neighbor's land, and I was a long way from the truck and the barn.

Keep in mind:  The truck (and obviously the barn) were never moved for this series of photographs.  They both remained in the exact same location.  I simply used lenses with different focal lengths to achieve this effect - to alter perspective.

Graphical diagram of the demonstration	Slide show composed of the individual photographs
This is a basic diagram to demonstrate what's going on. Click on the image below to enlarge the picture. It will open in a pdf document.	This slide show was graciously compiled by Kathleen Murtagh, from the individual pictures below.  It provides a better way to see what is happening as the lens focal length changes.
	The file size is 2.21 Mb If you have a slower internet connection, it is recommended that you view the individual pictures below. Click here to view the slide show Use your browser's "back" button to return to this page.

The table below shows the series of pictures that I took.  Click any image to enlarge.
You will then be able to advance through the sequence.

Focal Length	Full Frame (uncropped) image
15mm
18mm
20mm
24mm
35mm
50mm
70mm
80mm
105mm
135mm
200mm
250mm
300mm
350mm
400mm
450mm
500mm
550mm