Telescopic Magnification Flashcards
1
Q
Why is telescopic magnification more versatile than plus lens magnification
A
- can be produced at any viewing distance
2
Q
General formula for telescopic magnification
A
- M= -Fe/Fo
- t = f’e+f’o
3
Q
What is the exit pupil
A
- the image of the objective lens seen through the eye piece
- all rays entering the objective lens pass through the exit pupil
- important in defining the field and brightness of the image
4
Q
Formula for diameter of exit pupil
A
- diameter of objective lens/magnification of telescope
5
Q
Factors affecting a telescopes field of view
A
- magnification
- vertex distance
- object distance
- objective diameter
6
Q
Vengence amplification formulas (Frieds)
A
- L’=M2L
7
Q
How to adapt telescopes for near and intermediate viewing
A
- full correction for viewing distance over objective
- increased correction for viewing distance over eyepiece
- increasing the separation of Fe and Fo
8
Q
Formula for total magnification
A
- Mtotal = Mtel x Mrc
9
Q
Why use telescopes for near vision
A
- increase in working distance
- 2x greater than magnifiers
10
Q
How to compensate telescopes for ametropia
A
- full correction for refractive error behind eye piece
- partial correction for refractive error over objective
- changing the separation of Fe and Fo
11
Q
3 types of telescopes
A
- hand held
- clip on
- spec mounted
- Contact lens telescopes
