Telescopes

Question 1

astronomical telescope- keplarian

Answer 1

positive eyepiece 
positive objective
inverted image
erecting prisms needed
lightweight now, variable focus

Question 2

galilean telescope/ terrestrial

Answer 2

-ve eye piece, positive objective
common shaped
fixed focus
small, compact
upright image

Question 3

why are telescopes good

Answer 3

can increase angular subtense without a change in wd

Question 4

who are telescopes good for

Answer 4

people who visual demands of reading- at any D- but just at 1 D

Question 5

what does a telescope consist of

Answer 5

eye piece lens
and objective lens

in order to enlarge image- eyepiece must be the most powerful
for astronomical this must be a large -ve- but its ok as shows its inverted. and it corrected using prisms

Question 6

how do u calculate the enlargement of a telescope

Answer 6

• eyepiece power / power of objective

galilean are shorter than astronomical bc of their -ve lens

Question 7

how do u work out the length of a telescope

Answer 7

Focal length of eyepiece + focal length of objective

Question 8

how do u compensate for rx using a telescope

Answer 8

wear their distance rx?
add corrective lenses to eyepiece
alter the telescopic length- myopes will make telescope shorter- in a galilean there will be less enlargement but in an astronomical more enlargement
hype ropes make the gallileaon enlargement bigger, and astronomical image larger

Question 9

how do u adduct a d telescope for N

Answer 9

add a correcting lens

alter the length- increase the length for N- greater range with astronomical

Question 10

how do u calculate enlargement when an end cap is used

Answer 10

Enlargement of system =

E(telescope )x (End cap power / 4)

Question 11

whats the exit pupil for a telescope

Answer 11

where the pupil should be placed to view the object through the telescope

Question 12

how is the exit pupil diameter calculated ?

Answer 12

Fo/ enlargement

Question 13

how do u know which type of telescope it is looking at exit pupil and movements

Answer 13

if it moves with - gallileon

if it moves against then its an astronomical

Question 14

if u seen on a telescope 4 * 16 what does that mean?

Answer 14

enlargement and objective lens diameter

Question 15

how do u get the biggest fov

Answer 15

hold it right up against the eye

and pupil diameter should match the exit pupil diameter

Question 16

how lens seperation in a galleilion telescope is

Answer 16

posterior focal point of the objective coincides with the posterior focal point of the eyepiece

Question 17

telescope is focal and produces parallel emergent light from parralal incident light

Answer 17

accom needed for near-

magnification squared * wd in dioptres

Question 18

which optical performance is the best- telescope

Answer 18

astronomical

even in terms of FOV

Question 19

Gallelion telescope. The closer the exit pupil to the entrance pupil of the eye the

Answer 19

better the field of view- maximum light intensity and maximum image brightness

Question 20

gallilean telescopes have a virtual exit pupil due to the -ve lens

Answer 20

white disc that seems to lie anterior to the eyepiece.
exit pupil is within the system so not in the same plane as the entrance pupil of the eye
compromised
– field of view
– light intensity
– image brightness

Question 21

how lens separation in an astronomical telescope is

Answer 21

posterior focal point of the objective coincides with the anterior focal point of the eyepiece

Question 22

The exit pupil for the astronomical system

Answer 22

real and posterior to the eyepiece.
small disc that appears to float above the eyepiece lens.
optimise the field of view, light intensity and image brightness by aligning the exit pupil of the system with the entrance pupil of the eye

Question 23

small exit pupil in an astronomical telescope means

Answer 23

that the telescope has to be held close to the eye and very still
Field of view is reduced when the device is moved from eye
slightest movement- image moving in and out of view as the emergent light misses and then enters the ocular pupil

Question 24

which are more expensive- binocular or monocular

Answer 24

binocular

Question 25

px needs training and time to use a telescope. ons their health and manual dexterity is an issue to0

Answer 25

also like children- they can’t constantly adjust them, also they may break them. think about the pressure on their poor little nose. think about frame choice and nose pads

Question 26

for spotting short duration tasks

Answer 26

use a hand held telescope

Question 27

symptoms of oscillopsia and motion discomfort with telescopes bc of

Answer 27

sensory mismatch between the visual and vestibula-r ocular systems