Midterm 2: Telescopes Flashcards
What is the power exiting a telescope? What is this referred to?
Equivalent power of 0.
Afocal is 0 going in and 0 going out
Describe magnification in afocal telescopes. Does it have lateral mag? Does it have angular mag?
Afocal telescopes get magnification through shape factor
Lateral mag = 1.00x which is no change.
There is angular mag due to the shape factor which is… retinal image size with scope/ size without scope
Magnification formula for telescope
(-) ocular power / objective power
or
entrance pupil diameter/ exit pupil diameter
When do you have maximum field of view?
When your eye (entrance pupil) is located on the same plane as the exit pupil. This is on the outside of the telescope on the ocular side.
Keplarian telescope image properties. How to find tube length?
Image inverted.
Exit pupil outside of telescope on ocular side (good)
Find tube length by taking focal lengths of both lenses and adding together
Describe galilean telescope.
Objective: Plus Ocular: Minus Subtract focal lengths of lenses to get tube length (shorter tube length) Image upright Exit pupil inside telescope Better choice for low vision aids
For a galilean telescope, a myope would need a shorter or longer telescope?
Shorter
For a galilean telescope, a hyperobe would need a shorter or longer telescope?
longer
How do you make a terrestrial telescope?
Modified terrestrial telescope.
Increase tube length and add a third lens between the ocular and objective lens.
Put the secondary focal point for objective at the 2F for middle lens.
Put the primary focal point of the ocular lens at 2F’ of the middle lens.
Properties of terrestrial telescope
Image upright
FOV less that keplarian, more than galilean
longest tube length of the 3.
How much increase in tube length for a terrestrial telescope?
4x focal length of the terrestrial
