An astronomical telescope has an objective lens, whose job it is to gather light and create a sharp, and well focused image. A telescope is also made of an eyepiece, which can be more but is generally several lenses, that has a job to magnify a viewed object. The relay lens system is what creates an erect viewed image, as oppose to an inverted or mirrored image. The use of this lens system has resulted in telescopes that are longer but the system also assisted with the magnification variation of the telescope. At least, that is how it worked in the older days. Now a prism is used to right the image.
One can purchase a Barlow lens for their telescope that increases the effective focal length of the objective lens or primary mirror and provides double or triple the magnification of the eyepiece. Lenses which are used for the objective lens are achromatic lenses which are made from two layers of glass. This design was created so that no rainbow colors were seen around the image. The rainbow images which are created by a non-achromatic, or single lens, distorts the image and spoils the view.
The key elements of lens knowledge when it comes to telescopes is knowing whether a lens is achromatic, and being familiar with the objective lens. A powerful objective lens does not necessarily designate a superior telescope, as it is not the magnification power which an astronomer is after. It is also important to ensure that the lens on one's telescope has some sort of optical coating which ensure that as much light as possible is taken in by the telescope. The main goal of a telescope is to gather the light for an object in order to ensure that it is clearly seen.
Do you have something to say about Barlow Telescope Lenses? Be the first to comment using the space provided below.
Bookmark this page with:
Delicious
Digg
reddit
Facebook
StumbleUpon
More helpful advice in
The Forum
NASA Extends Space Station Cargo Delivery Contract
NASA has awarded Lockheed Martin Integrated Systems Inc. in Houston, a one-year contract extension v...
Shuttle Crew to Visit NASA Headquarters, Available for Interviews
NASA is developing new spacecraft, the Ares rockets and Orion crew capsule, to deliver astronauts to...
NASA Sets Launch Dates for Remaining Space Shuttle Missions
Following a detailed, integrated assessment, NASA selected target launch dates for the remaining eig...
College Students Design Future Aircraft in NASA Competition
Sixty-one students from 14 colleges and universities around the globe have imagined what the next ge...