query: I want to know about the relationship between focal length and aperture
positive_passages.docid: 11096
positive_passages.text: Why does my aperture setting change as I zoom on my DSLR kit lens?
negative_passages.docid: 101960
negative_passages.text: Why are crop lenses indicated with focal lengths they don't have?
negative_passages.docid: 129284
negative_passages.text: Why no zoom lenses with a maximum aperture wider than f/2.8?
negative_passages.docid: 113163
negative_passages.text: Why do some lenses focus past infinity?
negative_passages.docid: 80997
negative_passages.text: What advantages does manual mode have over aperture priority mode?
negative_passages.docid: 135149
negative_passages.text: How do camera body motors compare to in-lens motors for focusing?
negative_passages.docid: 96529
negative_passages.text: How can I calculate magnification ratio I get by reversing a lens?
negative_passages.docid: 113839
negative_passages.text: How can I visualize or simulate the effect of different focal lengths?
negative_passages.docid: 59156
negative_passages.text: What lens is needed to change the minimal focus distance length of my camera?
negative_passages.docid: 123605
negative_passages.text: Relation between intensity of light and refractive index
negative_passages.docid: 58265
negative_passages.text: What happens to a lens when you turn the focus ring during AF mode?
negative_passages.docid: 85095
negative_passages.text: Selecting optical size?
negative_passages.docid: 11197
negative_passages.text: How do I convert lens focal length (mm) to x-times optical zoom?
negative_passages.docid: 5000
negative_passages.text: Do smaller apertures provide more depth of field past the diffraction limit, even if peak sharpness suffers?
negative_passages.docid: 56452
negative_passages.text: What happens to waves when they hit smaller apertures than their wavelenghts?
negative_passages.docid: 88406
negative_passages.text: What does different focal length offer me?
negative_passages.docid: 21744
negative_passages.text: Focal length of an ellipse and related results