Experimenting with Image Formation

1. First, make two different "pupils" to cover the aperture in your pinhole camera. One of these should be a skinny horizontal rectangle and the other should be a skinny vertical rectangle. Remove your lens and place these in front of the large hole in your pinhole camera to see what the image looks like.Take three pictures of the viewing screen of your camera as you look at a bright scene: one with the original circular hole, one with the horizontal rectangle, and another with the vertical rectangle.What differences do you see in the picture? Try to explain why you see what you see in terms of the geometric optics and image formation principles we have discussed.Now put the lens in and re-take these three pictures:Does this change the outcome? Why or why not?
2. Try to estimate the focal length of the lens in your course kit. The easiest way to is to try and project a focused image of the sun onto another surface: Get somewhere where you can observe the sun (do NOT look directly at it!) and hold your lens so that sunlight passes through it onto another surface. You should be able to see the disc of the sun get blurrier or sharper as you move the lens closer to or further from the paper - at some critical distance it should be as clear as possible.Measure that distance between the lens and the paper and report it here.
3. Try taking a picture with your pinhole camera. Remove the lens and cover the large pinhole with a piece of cardboard and poke a smaller hole through it (this should be about the width of a pencil tip). Next put a piece of your sunprint paper into the back of the camera so that the blue surface is facing towards the pinhole. Choose an outdoor scene to take a picture of (indoor likely won't work!) and leave your camera for at least 30-60 minutes (longer is probably better).Develop your paper in water and include a picture of your print.What can you see in the image?