Given a text passage, come up with an appropriate title for it. The title should accurately represent what the main focus of the passage is. The title of a passage may be present in the first few sentences of the passage and/or be referred to multiple times in the passage. The title should be 1-5 words long.
Q: Lens speed refers to the maximum aperture diameter , or minimum f - number , of a photographic lens . A lens with a larger maximum aperture ( that is , a smaller minimum f - number ) is called a '' fast lens '' because it can achieve the same exposure with a faster shutter speed . Conversely , a smaller maximum aperture ( larger minimum f - number ) is '' slow '' because it delivers less light intensity and requires a slower ( longer ) shutter speed .
A:
Lens speed