Field of view: Understanding the Basics

[asa!!]

Hi.i have a question about Field of view. I know that it is an angle showing on a triangle.inside the area of the triangle any object can be photographed .am i right?i know tha it is not a scientific explanation, i am just saying what i have understood.

i have a camera. I do not know the focal length nor the frame size.i want to calculate the FOV.listen to what i thought.i did an experiment.i was taking photos of a wall with bricks so as to be able to calculate the size of the wall i was phtographing each time (by measuring the number of bricks and multiplying with the length of the brick).at each photo i was changing the distance between the camera and the wall. i imagined a equilateral triangle.the base is the size of the wall.the height is the distance between the camera and the wall. from there i calculated the tangent of the half angle of the triangle.then i found the half angle , multiplied it by two and i found the whole angle of the triangle. i think this is the FOV.am i right or i have done silly things?thank you very much

 

[Meir Achuz]

What you did sounds right to me, but I think you meant isoscelese, rather than "equilateral".

 

[brewnog]

Didn't you post this the other day?

 

[asa!!]

yes i did but you confused me a little bit with the number of pints.and since i did not get any other replies i post it again!thanks

 

[Nomy-the wanderer]

How come u don't know the frame size??

Anyway it's right what u do, there's another way..U can unmount the lens put it in direct sun light and try to gather the rays in a point on the surface, since direct sun light is in infinity and the rays will be gathered at the focal point u can measure the distance between the lens and the distance..Of course u've to move the lens back and forth to get the result...

But be carefull they say that such an act would create a burning fire, because the lens gathers heat on the surface..