7 Comentarios

1. 
   gauthierdumonde · 2012-09-07 20:48

   Super Shot.

2. 
   adash · 2012-09-07 21:34

   @gauthierdumonde Thanks. I believe it is more than 175 degrees....

3. 
   gauthierdumonde · 2012-09-08 06:53

   I think it will be close to 175. How did you do that? I am currently working on a wooden box and a curved plane, so I can get an angle of 130 degrees. It is quite job, building a wooden box. And I have lots of tin cans in al sizes (up to 30cm diameter). Maybe I just drill a hole in them and finish it with a pinhole made out a coke-can

4. 
   adash · 2012-09-08 07:13

   @gauthierdumonde The wall of the tin can is much thinner than the wall of a wooden box, so the paper can make a tighter curve inside. See the strawberry box on the left:
   e-p1.net/media/?sa=item;in=5810
   The pinhole is on the front, and the paper curves all the way, starting from the front wall, going to the back, and coming again to the front wall on the other side. If a stiffer paper is used, it can stay inside without touching the back wall, and have a smaller ratio between the sides, but with the same angle.
   The round cans are not perfect for such angles, because the angle of incidence between the light falling on the paper and paper itself is quite high on the sides, so it becomes very inefficient, although theoretically it should provide the same angle. In a rectangular box the light will still fall with a 90 deg angle on the paper, even on the very edge, as seen here.
   You don't need to stick an additional pinhole to the can, you can drill the pinhole inside the can itself. It is more difficult (the most difficult part is guessing where exactly the opposite of the yet un-drilled hole will be), but with practice it becomes OK.
   Black mate paint is a must, and the hole must be masked from the paint.
   And some plastic caps leak light, so black tape should be applied as seen on the photo.

5. 
   gauthierdumonde · 2012-09-08 07:58

   Thanks for the info. By the way I was not gonna drill a pinhol in the wood. I am gonna saw a hole about 5X5cm and then glue a thin metal plate inside, that is gonna have a pinhole. Focal distance will be 12.5cm and because of the curved plane (oval) the distance to the edges will be 14.5cm. So the light fall of will be minimal. When I should not curve my paper the focal distance would be 6.25cm, but the distance to the corners would be 12.5. So the image circle would not be sufficient to cover my paper. I will upload my sketch, you can review it :)

6. 
   adash · 2012-09-08 08:00

   @gauthierdumonde Please do. I will do my best. You can also send it to petrov.dimitar(at)gmail.com

7. 
   adash · 2012-12-02 20:27

   @gauthierdumonde I bumped into this old conversation, so....how is it going with your project?