Equations to learn

Question 1

Mag

Answer 1

Fe/4 times 1/1-wK

Fe= power of eye
w= working distance (m and negative)
K= ocular refraction

Question 2

Field of view

Answer 2

j(m)= g(k-w)/Fe

J= blur circle or field of view in m
G= pupil size in m
K- ocular refeaction
W= working distance in m and neg
Fe= 60

Remember to convert g to m
Convert w first to m and then make sure neg then do reciprocal then equation
Then times by 1000 at end

Question 3

Refractive error

Answer 3

K= 1/focal length (m)

Question 4

Circle of least confusion

Answer 4

Sphere power+ (cyl power/2)

Question 5

Far point

Answer 5

1/refeactive error

Question 6

Power

Answer 6

1/working distance (m)

Question 7

Fsp

Answer 7

Fsp= frev-w

Fsp spectacle lens
Frev=reversal lens
W= 1/working distance

Only subtract the sphere leave cylinder alone

Question 8

Speed of light

Answer 8

a/B= w-x/w-k

W= we’d in dioptres reciprocal
X= power of source
K= ocular refraction

Question 9

Speed of reflex how to work out x

Answer 9

X= 1/distance from eye

Distance from the eye is 1m+working distance Eg 0.67 if 2/3m
And then 1/ this ans

Question 10

how to get k for the speed of reflex equation

Answer 10

you just do sphere-cyl
or if its two negative powers add them