Midterm 2: Spectacle mag

Question 1

What side of lens is used for calculations for spectacle mag?

Answer 1

Outside surface (base curve)

Question 2

True or false:

For shape factor, even if the lenses have power, they are independent of power factor

Answer 2

True

Question 3

What surface of lens doesn’t affect shape factor?

Answer 3

Back surface power

Question 4

What do you need in order to find shape factor (big equation)

Answer 4

object distance, reference distance, thickness, index, front surface power

Question 5

Shape factor formula for far

Answer 5

1 / 1- (t/n) (F)

Question 6

Shape factor is directly proportional to what?

Answer 6

thickness

front surface power

Question 7

Shape factor is indirectly proportional to what?

Answer 7

front surface radius

lens index

Question 8

How do you find spec mag?

Answer 8

Shape factor x power factor

1 / (1 - t/n (F1)) x 1 / 1 - l (Fv’ back vertex)