Simple bedroom camera obscura for under $5

This Project was super simple and my 9 year old son did most of the work and even hosted a video about it.  This project can be done for under $5.

A camera obscura is simply a pinhole or a lens in a dark room that projects an upside down image onto a wall of the world outside.

 

Step 1 Measurements

The first step is to measure the distance from the window to the wall.  Ours was 3.3 meters. The lens we will need would be a focal length of 3.3 meters but eye doctors don't use focal length as a measurement, they use diopter.  The is simple to figure out by dividing 1 over the focal length.  This gave us .299 but these lenses are only made in .25 steps.  We rounded ours down to .25.  If you had the exact diopter for the room, the image would be sharper.  We went to the optometrist in town and when we explained what we were trying to do, they just gave us the lens.  Make sure you ask for a + or a converging lens. A - or diverging will not work for this.

The only other thing you have to measure is the size of the window frame.

Comments

[kill-a-watt]

Your math is off somewhere I think.

3.3 meters divided by 1 gets you 2.99? and you rounded to .25?

Was there a conversion to another unit somewhere?

[dave spencer]

.299 sorry, I messed up a decimal place. I have fixed it.

[kill-a-watt]

No problem. The math was only off enough to confuse, not to make a difference. You would have rounded to the same number anyway.

[kill-a-watt]

1 / 3.3 = 0.3030..

[kill-a-watt]

There are a bunch of cheap eyeglass ordering places on the internet. You could order a kid sized pair of glasses with two different strengths for $8 or so plus shipping

Also, dollar store reading glasses are converging lenses, so that could be another source.

[dave spencer]

Yeah but I got mine for free! Just go in and ask nice. Most towns have an optometrist.

[kill-a-watt]

I got an entire blank made of glass when I was a kid by asking nice. I said I wanted to make a telescope. The only problem was that it was a diverging lens.

I ended up using it as the mortar part of a mortar and pestle.

[CaseyCase]

When I was a teenager, I saw an "accidental" camera obscura effect created by a peephole in a door--it was pretty spectacular. Now if the wife will allow me to put one into the house somewhere.

[blodefood]

Great ible!

I have noticed that when it is bright outside and the curtains drawn, sometimes I get the right amount of space between the dark curtains and an image of the trees outside are on the opposite wall upside down.

[Kiteman]

Yay for science!