What is the focal length of an arbitrary parabola?
73233
Latus rectum of a parametric parabola
105343
Interference at the focus of a convex lens or a concave mirror
1032
What is the reference point that the focal length of a lens is calculated from?
80219
What is the relationship between field of view and focal length for fisheye?
151502
Finding the inverse of the arc length function
88283
Proving the length of angle bisector
113310
A question on the parabola..
150402
Is it normal for focal length to change while focusing?
39906
Equation of the locus of the foot of perpendicular from any focus upon any tangent to the ellipse ${x^2\over a^2}+{y^2\over b^2}=1$
37632
How to compare the focal length of a 50mm prime lens with the default lens of a point and shoot camera?
12994
Is it physically possible to build a long zoom (17-300 mm for example) at an aperture value of around 1.4 or 1.2?
83712
Volume calculation of truncated cones with elipses as base and top
94271
What is the reference plane used when the minimum focus distance is measured?
148913
Image of concave mirror when object is farther than the focal point
108518
Parametric Form for a General Parabola
8218
What's the arc length of an implicit function?
134974
What is the focal length on your typical cell phone camera?