Question

You just bought a new zoom lens for your camera and are trying it out by taking photos of aunt berta. First, you are playing around with the focal length, while making sure that she is in focus. Which one of the following is true?

1) The image will be blurry if the focal length is too short
2) The image will be blurry if the focal length is too long
3) The image will be sharp if the focal length is too short
4) The image will be sharp if the focal length is too long

Answer 1

The sharpness of an image depends on proper focusing, not simply the focal length of the camera lens. So long as the camera is focused correctly, an image can be sharp regardless of whether the focal length is short or long.

Step-by-step explanation:

When you adjust the focal length of your camera's zoom lens while making sure that Aunt Berta is in focus, neither the shortness nor the length of the focal length will inherently cause the image to be blurry. Focusing your camera correctly compensates for changes in focal length. Therefore, both statements 1) The image will be blurry if the focal length is too short and 2) The image will be blurry if the focal length is too long are incorrect if you are focusing properly. An image will be sharp if the camera is properly focused, regardless of whether the focal length is short or long. If the subject is out of focus, the image will appear blurry, which might require adjusting the distance between the lens and the sensor. This adjustment is required because the object distance changes and, with a fixed focal length, the lens must be moved to maintain a sharp image.