Focal length

Focal

Focal Length

Focal blur

Focal point

First Focus

Second Focus

Focal Length

Focal length

And this is f2.

And it's for focus.

Focal length of the lens

Well, we just used the distance formula.

Or they can be, I don't want to say always.

We have focused on the worst case scenario.

That's our directrix and it has the equation y is equal to k.

And what we want to do is, we want to find out the coordinates of the focal points.

Ellipse by Focuses Point

The coordinate of this focus right there is going to be 1 plus the square root of 5, minus 2.

I want to focus on just one of them.

35mm equivalent focal length

That's this distance right there.

And that's what we set out to figure out in the beginning.

And you enter that space, and you feel like, Wow!

Requires great focus.

Just focus.

Bifocals.

Your focus,

There and there.

Hyperbola by Focuses Point

I'll call that well, we'll call that a focus because it will be a focus.

But where's the focus point?

So you know that a is equal to x1.

So let's solve for the focal length.

Focal Length

Telescope focal length

Eyepiece focal length

So let's call that a directrix.

I won't revise this equation, but this is the fundamental equation that governs when things are in focus, for a lens.

I thought it looked kind of a little bit like the Moon, which is sort of interesting.

An object at range of 100 meters

And you essentially divide 1 by 4 times this value.

Well, the first thing you do is though I've never well, we could just figure out the focal length just by plugging into the formula.

Show camera aperture and focal length

Construct an ellipse with this focus