8 - LV/Mag Equations

Question 1

Relative distance magnification (RDM)

Answer 1

RDM = original distance ÷ new distance

Question 2

Relative size magnification (RSM)

Answer 2

RSM = new size ÷ old size

Question 3

Lateral/geometrical magnification

Answer 3

M = hi/ho = L/L’ = l’/l

Question 4

Hand-held magnifier total magnification

Answer 4

HHM = abs(u)*F

HHM = abs(orig dist bw object and eye)*power of lens

Think HHM, ugh Fuck

Question 5

Hand-held magnifier effective magnification

Answer 5

EM = F/4

What’s on labels, uses standard dist of 25cm

Question 6

HHM linear field of view

Answer 6

FOV = d ÷ (Feℓ)

= diameter of lens ÷ (equiv power*dist from HHM to spec plane)

Question 7

Stand magnifier total angular magnification

Answer 7

TAM = mM

= lateral magnification * RDM

In class we used Enlargement * RDM

Question 8

Stand magnifier + add lens magnification

Answer 8

M = Equivalent power ÷ 4

Max = this + 1

Question 9

Telescope tube length

Answer 9

d = ƒ(obj) + ƒ(oc)

= focal length objective + focal length ocular

Question 10

Magnification of telescope (2)

Answer 10

MTS = -(F(oc) ÷ F(obj))

MTS = diameter entrance pupil ÷ diameter exit pupil

Question 11

Telemicroscope magnification

Answer 11

TMS = M(reading cap) * M(telescope)

Question 12

Telemicroscope reading cap magnification (2)

Answer 12

MRC = abs(u)F
= abs(orig dist bw object and eye)power of reading cap
(ugh Fuck)

MRC = F ÷ 4

Question 13

Snellen/M size conversion

Answer 13

Test distance/M = 20ft/snellen

Question 14

Predicting add

• Kestenbaums
• lighthouse

Answer 14

K: inverse of distance BCVA

L: add = (got ÷ need)*WD
WD is in DIOPTERS