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SCHMIDT-CASSEGRAIN TELESCOPES

10

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A CLOSER LOOK AT SCHMIDT CASSEGRAINS

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Collimation

Cont'd.
collimation telescopes
If you remove your eyepiece from the telescope and look inside you will see the secondary (diagonal ) mirror. In the reflection you will see roughly what you see with the eyepiece in the collimation star test. Right in the center should be the reflection of your eye. This should be perfectly centered in the reflection of the diagonal, which should be dead in the center of the rest of the reflection which is the main mirror. The best way to get an accurate alignment is to know if your looking directly straight down the eyepiece tube. Collimation tools can be bought for ease of adjustment.
TELESCOPE LINKS:
Basics
Mounts
Light Gathering Power
Closer Look At Refractors
Dimensions
Balancing
Schmidt-Cassegrains can be available in a shorter focal ratios. These
Eyepieces
are designed more for astrophotography to help keep exposures short.
Cleaning
Tips
The camera film will see more light with the shorter focal ratio, but this is not the same for what we see with our eyes through the telescope.
Astrophotography
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Maksutov-Cassegrains Reflectors

Similar to the Schmidt-Cassegrain, the Maksutov-Cassegrain uses a main mirror and a lens (hyperbola secondary mirror) it also has a corrector plate to eliminate the spherical aberration. The Maksutov is a great design for detailed views and photographs of the planets and Moon. The secondary mirror is glued onto the back of the corrector plate instead of being held by brackets. This cuts down the obstruction in front of the main mirror, which means higher resolution and light gathering. The corrector plate of the Maksutov is different in design to the Schmidt. It uses a thick meniscus lens to overcome the spherical aberration. The price per centimeter of aperture is probably the highest of any telescope since they are hand figured. Maksutovs are generally small aperture (size) telescopes because of their price, with the popular one being the 150mm(6") models. They have long focal ratios (dimensions) but are still compact. The path which the the light travels in Maksutovs is the same as the Schmidt-Cassegrain. The collimation shouldn't go out on one of these, but if their is suspicion that it has, it's best to call us to confirm and then correct it properly according to manufacturers specifications.
Binoculars
collimation
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END OF A CLOSER LOOK AT SCHMIDT CASSEGRAIN & MAKSUTOV REFLECTORS

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