You want to take a full length photo of your friend who is 2 m tall, using a 35 mm camera having a 50 mm lens. The image dimensions of 35 mm film is 24 mm by 36 mm, and you want to make this a vertical photo in which your friend's image completely fills the image area. (a) How far should your friend stand from the lens? (b) How far is the lens from the film?
ok.. I am confused..help please!
Sure, let's break it down step by step.
(a) To determine how far your friend should stand from the lens, we need to find the distance between the lens and your friend that will result in a full-length photo.
Here's how you can find this distance:
1. Start with the image dimensions of the film, which are given as 24 mm by 36 mm.
2. Since you want to make a vertical photo, we can consider the 24 mm dimension as the height of the final image.
3. Your friend is 2 m (2000 mm) tall, so the height of your friend's image in the final photo should be 24 mm.
4. Now, you can set up a proportion to find the distance between your friend and the lens. Let 'x' represent that distance:
2000 mm (friend's height) / x (distance) = 24 mm (image height) / 24 mm (film height)
Simplifying the proportion:
2000 mm / x = 24 mm / 24 mm
2000 mm / x = 1
To solve for 'x', we can cross-multiply:
24 mm * x = 2000 mm
x = 2000 mm / 24 mm
x ≈ 83.33 mm
So, your friend should stand approximately 83.33 mm from the lens to have a full-length photo.
(b) Now let's calculate the distance between the lens and the film. This distance is known as the "focal length" of the lens.
1. The focal length of the lens is given as 50 mm.
2. The lens projects an image onto the film, so the distance between the lens and the film should be equal to the focal length.
Therefore, the lens should be approximately 50 mm away from the film.
I hope this clarifies things for you! Let me know if you have any further questions.