Assignment #21, perspective and image compression

Posted: Sun Oct 15, 2006 7:14 pm

Photography is a 2 dimensional medium. We are usually trying to represent 3 dimensional subjects and several of the previous assignments were designed towards that end.

In this assignment we are going to look at image compression and perspective and the effect UV has on the sense of depth.

Image compression is the effect that you get when you shoot distant objects with your longest telephoto lens.

For this assignment you should select a subject with several planes, all at or past your infinity focus. Shoot it first with your longest telephoto lens. Then repeat that with your widest lens.

Enlarge the small section of the wide angle shot so that it is exactly the same size as the shot taken with your telephoto. Post and label both.

Perspective is controlled by distance. Nothing else. Just distance. The differing focal lengths alter the angle of view only. They do not alter the perspective in any way.

Also, despite the fact that there is image compression, that is the distant planes appear to be one atop another, the UV in the atmosphere will create an increasingly less saturated and less contrasty image the further the lens looks into the distance.

In the linked mountain scene, the increasing loss of contrast and saturation is apparent. (Note: Do not use an UV filter or Polarizing filter for this assignment--it will diminish this effect).

Mountains Note especially "View from Oberlin"

And this shot from the Vietnam War: War (click "machines" and then "continue" for 7 clicks until you get to the helicopter shot).

Note the diminishing contrast and saturation in the background.

OK. Two (2) shots. From the identical location; same exposure, one with your longest lens and one with your shortest lens. Go for it.

Posted: Sun Nov 26, 2006 10:05 pm

I guess I need a telephoto lens for this one. I have seen some on ebaythat can attatch to the filter thread on my one and only lens. Real cheap to but I don't think its really a telephoto lens! I Have a Canon Rebel XTI what are my options for an entry level tele photo lens?
peace tjd!

Posted: Fri Dec 01, 2006 2:20 am

tjdscion wrote:

I guess I need a telephoto lens for this one. I have seen some on ebaythat can attatch to the filter thread on my one and only lens. Real cheap to but I don't think its really a telephoto lens! I Have a Canon Rebel XTI what are my options for an entry level tele photo lens?
peace tjd!

You could accomplish the goals of this assignment by using the 55mm and 18mm ends of your lens, in my opinion, though I'll defer to Packard for the final call here as he's the designer & judge of these things.