Session 14

Question 1

What does this formula solve?
F1/(1-t/n(F1))+(F2)

Answer 1

FV’ Back Vertex Power

Question 2

What does this formula solve?
F2/(1-t/n(F2))+(F1)

Answer 2

Fv Front vertex Power

Question 3

What is the rule for a Plus Meniscus Lens with Ft, Fv, Fv’ ?

Answer 3

Ft(Nominal Power) is the least plus,
Fv(front vertex power) is slightly more plus.
Fv’(back vertex power) is the most plus.

Question 4

What is the rule for a Minus Meniscus Lens with Ft, Fv, Fv’ ?

Answer 4

Fv(front vertex power) is the least minus,
Fv’(back vertex power) is a little more minus.
Ft(Nominal Power) is the most minus.

Question 5

Practice examples of finding front and back vertex distance.