00:02
All right, so you have a couple of questions about the components of a telescope and how we can use the information given in the prop to make some predictions about the telescope.
00:17
So diopters is a measurement that's inversely related to the focal point in meters.
00:24
So if we just take the inverse of the diopters, we're going to get the focal point in meters.
00:30
So that's what i did.
00:32
I did f1.
00:33
That's my one lens is 1 over 12, so 0 .083 meters.
00:40
And then f2 is going to be 1 over 1 .1, which gets this 0 .91 meters.
00:49
So in general, we should make our objective lens always the one that has the higher, larger focal point.
00:56
Because that way our eyepiece, otherwise we have to stand really far away from our eye piece to be a able to see something.
01:03
So we want to be able to be closer to the eye piece with our own eye.
01:09
So that would be eight centimeters away on this.
01:14
So that's a lot better than almost a full meter away, which would be almost three feet away from the telescope.
01:21
They'll see anything.
01:23
So we're going to make our objective, the 1 .1 diopter lens.
01:27
And then our eye piece is going to be the 12 diopter lens.
01:30
So i kind of made like a little.
01:32
Drawing of that just to organize my thoughts.
01:36
The second thing that i need to know is, where do i place this other lens? well, it's all based on this, the lens equation, 1 over f equals 1 over d .i plus 1 over do.
01:50
And the challenge here is where you don't necessarily know where the d -o is.
01:54
Well, it's going to be really far away for the most part.
01:57
And so if we look at our mathematics involved here, one divided by a really large number is basically like adding this really, really tiny number all the way to a limit of zero.
02:12
So if i make this do infinity, this drops off to zero.
02:17
That's kind of the trick for a telescope when we want to figure out where do we put our objective lens.
02:24
Now, or i mean our i piece...