| Basic Telescope DesignsThe job of a
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| | maintenance, such as collimation
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| telescope is to collect light, not to
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| | (discussed in another article) which is
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| magnify an image (the eyepiece does that
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| | vital for great results in your
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| job). The larger the objective (the part
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| | astrophotography, although you will learn
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| that collects the light) whether it be a
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| | how to do this quickly with
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| lens, in refractors, or a mirror, in
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| | practice.Schmidt-Cassegrain
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| reflectors, the more light the telescope
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| | TelescopesThis is a very popular design,
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| will collect. The more light you can
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| | with a high tech look. Also known as a
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| collect, the more detail you will be able
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| | CAT (Catadrioptics). They use a
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| to capture, and also important for
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| | combination of lenses and mirrors to
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| astrophotography, the shorter your
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| | collect and focus the light onto the
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| exposures will need to be to capture this
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| | eyepiece or camera. The light enters the
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| detail.Refractor TelescopesThe type of
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| | telescope through a thin 'lens' called a
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| telescope most people visualize when they
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| | schmidt corrector plate, goes to the back
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| hear the word telescope is the
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| | of the scope to a spherical primary
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| 'Refractor'. This is what Galileo used
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| | mirror which reflects the light back
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| for his break-thru discoveries. A
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| | towards the front. Here the light strikes
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| refractor has an objective lens at the
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| | another mirror, the secondary mirror
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| front which passes the light straight
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| | which is mounted on the corrector plate.
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| through to the back of the tube, focusing
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| | This secondary mirror then reflects the
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| this light at an eyepiece or for
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| | light back towards the back where it is
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| astrophotography a camera.Advantages:-No
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| | focused onto a hole in the primary mirror
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| central obstruction (see more in the
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| | where the light is collected by an
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| reflecting scopes), giving higher
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| | eyepiece or your astrophotography
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| contrast.-Due to the simple design they
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| | camera.Advantages:-Compact and
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| require little maintenance.-Excellent for
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| | portable.-Low maintenance although once
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| planetary and lunar viewing and
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| | again collimation is required for top
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| photography.-Excellent for wide field
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| | performance.-Many, many astrophotography
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| viewing and astrophotography especially
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| | accessories available.-Cheaper per inch
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| in shorter focal lengths (more on this
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| | of aperture as compared with
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| later).-Because the objective is
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| | refractors.-Excellent all-round
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| permanently mounted and aligned there is
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| | telescope, good to very good for both
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| no need for collimation (again more on
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| | visual and astrophography.-Very good for
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| this in another article).-Excellent color
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| | planetary and lunar viewing and
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| in apochromatic and ED (Extra Dispersion)
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| | astrophotography.-Very good to excellent
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| designs.Disadvantages:-Costlier per inch
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| | for DSO (Deep Space Object)
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| of aperture (objective) than reflectors
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| | astrophotography with a caveat (see the
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| and catadioptric telescopes.-Can become
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| | disadvantages).-Very good to excellent
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| bulky and difficult to manage, especially
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| | optics, both Meade and Celestron are
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| in larger lens designs.Newtonian
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| | putting out excellent optics on a
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| TelescopesThis design was invented by Sir
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| | consistant basis.Disadvantages:-Costlier
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| Isaac Newton (he of the apple on the head
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| | per inch of aperture as compared with
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| fame). Instead of a lens at the front of
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| | Newtonian telescopes.-Loss of contrast
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| the tube this telescope design uses a
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| | due to the central obstruction which is
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| concave, parabolic mirror to collect
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| | even larger than that in the Newtonian
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| light reflecting it back towards the
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| | scopes.-Due to their longer focal lengths
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| front of the tube to a flat diagonal
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| | the field of view is smaller and longer
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| mirror which reflects the light out the
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| | exposures are required for
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| side of the telescope to the eyepiece or
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| | astrophotography, although a lens known
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| camera for
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| | as a focal reducer is available which
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| astrophotography.Advantages:-Lowest cost
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| | minimizes or removes this problem. The
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| per inch of all the telescope
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| | longer focal length is actually an
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| designs.-More light gathering power per
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| | advantage in planetary and lunar
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| dollar because of the lower cost
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| | photography.Maksutov-CassegrainThe
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| design.-Absolutely perfect color
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| | Maksutov-Cassegrain telescope design is
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| rendition.-More compact design compared
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| | basically the same as the
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| to a refractor of similar light gathering
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| | Schmidt-Cassegrain design except it uses
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| ability.-Excellent contrast for planetary
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| | a meniscus lens at the front instead of a
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| and lunar astrophotography and viewing in
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| | Schmidt corrector plate. The main
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| longer focal lengths.-Can get excellent
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| | advantage to the Mak telescope design is
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| wide-field astrophotos and short
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| | you will get sharper higher contrast
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| exposures in shorter focal
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| | planetary and lunar images when compared
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| lengths.Disadvantages:-Slight loss of
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| | with the Schmidt design.Carl Gilbertson
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| contrast due to the central obstruction
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| | has been involved in amatuer astronomy
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| (the flat secondary mirror) as compared
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| | for over 30 years and astrophotography
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| to a refractor.-Requires more
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| | for over twenty-five years.
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