Types Of Telescopes For Astronomy

Types Of Telescopes For Astronomy

Fundamental Telescope Designs

The job of a telescope is to collect light, not to magnify an image (the eyepiece does that job). The larger the objective (the part that collects the light) whether it's a lens, in refractors, or a mirror, in reflectors, the more light the telescope will collect. The more light you'll be able to acquire, the more element you can be able to seize, and in addition vital for astrophotography, the shorter your exposures will should be to seize this detail.

Refractor Telescopes

The type of telescope most people visualize once they hear the word telescope is the 'Refractor'. This is what Galileo used for his break-by means of discoveries. A refractor has an objective lens on the front which passes the light straight by to the back of the tube, focusing this light at an eyepiece or for astrophotography a camera.

Advantages:

-No central obstruction (see more within the reflecting scopes), giving higher contrast.

-As a result of easy design they require little maintenance.

-Excellent for planetary and lunar viewing and photography.

-Wonderful for huge field viewing and astrophotography particularly in shorter focal lengths (more on this later).

-Because the target is completely mounted and aligned there is no such thing as a want for collimation (once more more on this in another article).

-Wonderful coloration in apochromatic and ED (Extra Dispersion) designs.

Disadvantages:

-Costlier per inch of aperture (objective) than reflectors and catadioptric telescopes.

-Can become bulky and difficult to handle, particularly in bigger lens designs.

Newtonian Telescopes

This design was invented by Sir Isaac Newton (he of the apple on the head fame). Instead of a lens at the entrance of the tube this telescope design uses a concave, parabolic mirror to gather light reflecting it back towards the front of the tube to a flat diagonal mirror which reflects the light out the side of the telescope to the eyepiece or camera for astrophotography.

Advantages:

-Lowest cost per inch of all the telescope designs.

-More light gathering power per dollar because of the lower cost design.

-Absolutely good shade rendition.

-More compact design compared to a refractor of similar light gathering ability.

-Glorious contrast for planetary and lunar astrophotography and viewing in longer focal lengths.

-Can get excellent extensive-subject astrophotos and brief exposures in shorter focal lengths.

Disadvantages:

-Slight loss of distinction because of the central obstruction (the flat secondary mirror) as compared to a refractor.

-Requires more upkeep, equivalent to collimation (discussed in another article) which is significant for great results in your astrophotography, though you'll discover ways to do this rapidly with practice.

Schmidt-Cassegrain Telescopes

This is a very popular design, with a high tech look. Also referred to as a CAT (Catadrioptics). They use a mix of lenses and mirrors to gather and focus the light onto the eyepiece or camera. The light enters the telescope via a thin 'lens' called a schmidt corrector plate, Astranaut Art goes to the back of the scope to a spherical major mirror which reflects the light back towards the front. Right here the light strikes one other mirror, the secondary mirror which is mounted on the corrector plate. This secondary mirror then reflects the light back towards the back the place it's centered onto a gap in the major mirror the place the light is collected by an eyepiece or your astrophotography camera.

Advantages:

-Compact and portable.

-Low maintenance although once again collimation is required for high performance.

-Many, many astrophotography equipment available.

-Cheaper per inch of aperture as compared with refractors.

-Glorious all-spherical telescope, good to excellent for both visual and astrophography.

-Very good for planetary and lunar viewing and astrophotography.

-Excellent to excellent for DSO (Deep House Object) astrophotography with a caveat (see the disadvantages).

-Superb to excellent optics, both Meade and Celestron are placing out excellent optics on a consistent basis.

Disadvantages:

-Costlier per inch of aperture as compared with Newtonian telescopes.

-Loss of contrast because of the central obstruction which is even larger than that in the Newtonian scopes.

-Resulting from their longer focal lengths the sector of view is smaller and longer exposures are required for astrophotography, though a lens often called a focal reducer is available which minimizes or removes this problem. The longer focal size is actually an advantage in planetary and lunar photography.
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