There are a few reasons: Quality of the glass. Unless the glass in a lens is perfectly homogenic, a lot of blurring will occur. With a (surface) mirror the quality of the material behind the silvering is unimportant.
Why do you think the primary or objective lens of refracting telescope should have a longer focal length?
The focal length is the length from the aperture to the focal point of the telescope. The longer the focal length, the smaller the patch of sky you’re observing. But a longer focal length also gives a higher possible magnification.
Why do we build telescopes with large primary mirrors?
A large primary mirror collects incoming light and reflects it to a focus. The light is reflected a second time by the smaller secondary mirror, to form an image on an instrument located at a safe, accessible place below the primary mirror, where the image is recorded.
Why it is better to use mirrors in telescopes than lenses?
So why do we use mirrors today? Because mirrors are lighter, and they are easier than lenses to make perfectly smooth. The mirrors or lenses in a telescope are called the “optics.” Really powerful telescopes can see very dim things and things that are really far away.
What two advantages do you get from having a telescope primary mirror with a very large diameter compared to a small diameter mirror?
Terms in this set (76) What are two advantages of large scopes over smaller ones? Large telescope have more light grasp and better resolution. This design involves only one optical surface, a concave mirror.
How do mirrors work in telescopes?
They use mirrors to collect and focus the light towards the eyepiece. Mirrors are lighter than lenses and they are also easier to shape into a smooth and perfect surface. If there are any flaws in a telescope’s optics (eg. the mirrors or lenses) then the image created will appear warped or out-of-focus and blurry.
Why are concave mirrors used in telescopes?
Light enters the telescope at the right and travels to a concave mirror. … The light is then reflected back again out of the back of the telescope to the eyepiece and the eye. Like the Reflector, uses a concave mirror as its primary objective to focus the incoming light.