query: Why don't all zoom lenses have variable f-numbers?
positive_passages.docid: 145622
positive_passages.text: How do constant aperture zoom lenses work?
negative_passages.docid: 47999
negative_passages.text: How do you find out the "sweet spot" of a lens?
negative_passages.docid: 54122
negative_passages.text: Why does using a tilt-shift lens make things look miniature?
negative_passages.docid: 129613
negative_passages.text: Why does illuminance stay the same for a given f-stop even when focal length changes?
negative_passages.docid: 11197
negative_passages.text: How do I convert lens focal length (mm) to x-times optical zoom?
negative_passages.docid: 101960
negative_passages.text: Why are crop lenses indicated with focal lengths they don't have?
negative_passages.docid: 130570
negative_passages.text: Why can't my SLR autofocus on certain parts of a scene?
negative_passages.docid: 70690
negative_passages.text: Why are only certain shutter speeds or apertures available?
negative_passages.docid: 139331
negative_passages.text: Why doesn't exposure change when changing focal length?
negative_passages.docid: 71754
negative_passages.text: Why do two zoom lenses set to 200mm on the same camera produce different fields of view?
negative_passages.docid: 20086
negative_passages.text: Why is the amount of light a lens lets in called the 'lens speed'?
negative_passages.docid: 77417
negative_passages.text: Why do I get "F - -" on my Nikon camera?
negative_passages.docid: 62759
negative_passages.text: Why am I allowed to turn my focusing ring beyond infinity?
negative_passages.docid: 148588
negative_passages.text: Lens correction in darktable when my lens isn't known?
negative_passages.docid: 63434
negative_passages.text: Technically, why is the out of focus area blurred more when using a bigger aperture?
negative_passages.docid: 95539
negative_passages.text: Do lenses affect color fidelity?
negative_passages.docid: 10570
negative_passages.text: Does sensor size affect lens distortion?