Wednesday, January 28, 2009

Camera obscura and critical thinking

In the olden days, a cameras (like a car motor) could be grasped with a little bit of sense and a dollop of curiosity.

Light traveled through a piece of glass, a lens you could screw off the camera. Hold the lens a foot or two away, and the image flipped.

The lens was attached to a box that had a shutter you opened and closed to let in the light. You could vary the time it was open. You could vary how large the opening was.

The light was focused on film, a strip of plastic (originally a wet concoction of cellulose and other stuff to make "dope"), that reacted to the light. High school kids could hang out in dark rooms developing film (and a finer sense of anatomy).

The whole process was tangible. (That the dark room featured a red light added to the, um, tangibility.)

For kicks you could make a shoe box pinhole camera, and take interesting photos with unreal depth of field. Cool and cheap, when cheap was cool.

So what does this have to do with today's media savvy tween digerati set?

Ah, grasshopper....

First, though, all you young'uns who never saw a pinhole camera before need to gather a toilet paper roll, a piece of waxed paper, a piece of aluminum foil, anda couple of rubber bands.

(No, you can't do this get to use all 10 fingers for this. Too clever by half....)

Put a small hole in the foil, attach it to one end of the tube, with the hole centered. Fold the waxed paper over the other end. Yep, use the rubber bands to hold it all together.

Point the aluminum side at a bright light source, focus on the waxed paper screen, and tell me what you see. Move it around a bit, what happens?

[OK, for those who cannot help themselves, I'll save you the trip to Google--you wil see an upside-down image that moves oppositee to the direction you move the camera.]

That's the observation, now here's the question--how can an image flip if there are no lenses? What can you infer about the property of light (at least here in our Newtonian sensate universe)?

And I will leave this open for now....


Kate Tabor said...

Hello! Our sixth and seventh grade photo students make and use pinhole cameras. They actually take and develop photos that they capture with their oatmeal box cameras. An interior photo takes almost an hour to expose. I'm not sure if they think about the properties of light or if they just wish they could get their hands on a digital camera.

I should get my own sixth graders to make cameras.

Of course the camera obscura is quite controversial in the world of art - did those amazing Flemish painters "cheat" and use one?

doyle said...

Good afternoon!

Oatmeal boxes would work better than the toilet paper rolls, I imagine.

The amazing Flemish painters still work for us even today, no matter how they got their work done, but I'm an art knucklehead, so not sure my opinion counts.

How do you hold the camera still for so long?

Paul said...

Students are often definitely confused about the inverted image. My experience is that that partially has to do with the fact that so many pinhole camera diagrams only represent the light that happens to pass through the pinhole. So you end up with a picture in which all of the represented light contributes to the image, which sort of obscures the fact that the image is inverted because so much light doesn't contribute to the image.

doyle said...

Dear Paul,

"...the image is inverted because so much light doesn't contribute to the image."

Ah, that's a succinct and elegant way of looking at it--and how I will present it in class next year. Thanks!

Kate Tabor said...

More than one student has set up their oatmeal box in my room on a desk or a ledge and sat down next to it with a book. They liked my seventh grade classroom because two walls of that room are all window.

And as far as Vermeer goes - it's all speculation although the English painter David Hockney is a huge fan of projection techniques. I'm an art philistine myself, but as one of my favorite painters (Thomas Eakins - watercolorist) has been accused of using projection techniques I have chased some readings. If you are curious about Vermeer.

doyle said...

Dear Kate,

Your prompt and my curiosity just got me a new post idea--I am going to carry this over to the front page in a day or two.


Adrienne said...

The English teacher in me wants to overflow with all sorts of metaphor and other silliness about light that your post clarifies so beautifully. For now I'll simply say that to me, the pinhole camera (which I have not thought of in many years!) certainly exemplifies how light can simultaneously reveal and conceal what we believe to be real right in front of us.