When you increase the focal length but leave the negative size the same all you do is decrease the "angle of acceptance" of the light beam. You sample a smaller portion of the potential image. I can't see how the size of the pinhole would make a difference, except that it casts an optimal potential image that is greater in radius. I figure out these things by drawing them out. I suspect Trigonometry would work but to me that's a dark science, one to which I have not been admitted. ----- Original Message ----- From: "Joao Ribeiro" <jribe...@greco.com.br> To: <pinhole-discussion@p at ???????> Sent: Monday, February 11, 2002 6:51 PM Subject: [pinhole-discussion] Angle of ligh
> Hi folks, > > I have a question, but I'm not sure I'll be able to put it properly. > Here it goes: > > When the light enters the camera, it enters in an angle the depends on > the pinhole diameter or this angle is constant? > Imagine I have a pinhole of 0.5 mm. If I make a bellows camera and set > it to say 50 mm focal distance using an 8x10 film I'll have a very wide > angle image. But if I enlarge the bellows distance to 500 mm I'll then > have a telephoto image. Well, actually the image "cone" will be the > same, I'm just choosing a section of the cone farther away from the > pinhole or origin, and I am also selecting part of this cone to be > recorded. How can I calculate the cone angle? Will changes in the > pinhole diameter make any difference in this angle or it will always be > constant? > > I hope I could make myself clear! > Thanks in advance for any info, > > Joao > > > _______________________________________________ > Post to the list as PLAIN TEXT only - no HTML > Pinhole-Discussion mailing list > Pinhole-Discussion@p at ??????? > unsubscribe or change your account at > http://www.???????/discussion/ >
