1. Astronomical Refracting Telescopes
A refracting telescope uses two converging lenses. The first objective lens forms a real image which is then magnified by the eyepiece lens. This is the ray diagram you need to be able to draw.
2. Magnification of Refracting Telescopes
The purpose of any telescope is to magnify distant objects. There are a couple of ways to calculate the magnification which this video explains in a little more detail.
3. Cassegrain Reflecting Telescopes
Larger telescopes generally use mirrors to reflect light from a large parabolic concave mirror to a secondary mirror then finally through a lens to form an image.
4. Refracting vs. Reflecting
There are a number of issues with both refracting and reflecting telescopes. This includes spherical and chromatic aberrations due to the way light travels through the lens.
5. Radio, IR, UV and X-ray Telescopes
By investigating all sorts of EM radiation we can build up a greater picture of objects than if we were to just use visible light. This is how.
6. Rayleigh Criterion
This video is ok - but I think I mispronounced Rayleigh. Until I film another one this should do. I discuss the limit in resolution and the Rayleigh Criterion.
7. Quantum Efficiency, CCDs and the Eye
To record the images formed by telescopes we use Charged Couple Devices. These detect the photons and send a signal which can then be processed.