If I had the old-fashion camera that had a focal length of 35mm(0.035m) and I take a picture of a person 6 feet away, how far does the film need to be from the lens to record a clear image?
Please help-if you could just suggest an equation-that would be helpful
To find the distance the film needs to be from the lens to record a clear image, you can use the thin lens formula:
1/f = 1/u + 1/v
Where:
f = focal length of the lens (in meters)
u = object distance from the lens (in meters)
v = image distance from the lens (in meters)
Since you want to photograph a person 6 feet away, you need to convert this distance to meters by multiplying it by 0.3048.
u = 6 feet * 0.3048 meters/foot = 1.8288 meters
Now, you can substitute the given values into the equation, with the focal length of the lens (f) being 0.035 meters:
1/0.035 = 1/1.8288 + 1/v
Simplifying further:
28.5714 = 0.5464 + 1/v
Subtracting 0.5464 from both sides:
28.0249 = 1/v
Taking the reciprocal of both sides:
v = 1/28.0249
Calculating the value:
v ≈ 0.0357 meters
Therefore, the film needs to be approximately 0.0357 meters away from the lens to record a clear image.