Telescope Basics (Reflector, Refractor, Schmidt-Cassegrain)

Beginners Guide and Tutorial for Reflector, Refractor, and Schmidt-Cassegrain telescopes, Alt-Azimuth and Equatorial mounts, benefits, and comparisons.

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Science & Technology

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• tutorial
• beginner
• basics
• telescope
• Astronomy
• alt
• azimuth
• mounts
• optics
• reflector
• refractor
• schmidt
• cassegrain
• eyepiece
• mirror
• stars
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• tristate
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[Huronhumedo]

The reflectors are not suitable for deep sky observation

[DeepSkyDan]

@Huronhumedo Actually, reflectors are the best for deep sky observations. Most world class telescopes are reflectors. As an example the Keck telescope is a 10 meter diameter reflector. Also the Hubble Telescope is a reflector. (Ritchey–Chrétien).

Perhaps you are thinking of refractors. They are also OK for deep sky observations, but their size, weight, and cost are quickly out performed by reflectors.

[Huronhumedo]

@DeepSkyDan but if I have to choose between a 127 mm catadioptric Maksutov and a 130 mm reflector what would be best to observe deep space objects (like nebulae) and galaxies? Celestron nexstar 127 slt and 130slt

[DeepSkyDan]

@Huronhumedo For the models you have selected I don't think you will see any difference for casual observing for deep space objects. You can think of the Maksutov as a 'folded reflector'. It is shorter and easier to handle (which means you might set it up more often). The Maksutov is not as easy to collimate (align the mirrors) as a reflector, should the need arise. The Maksutov has sealed optics, the reflector is completely open to dirt. Personally I'd choose the reflector.

[lotsofsmarts]

what is the "blocked" ?

[DeepSkyDan]

@lotsofsmarts "Blocked means that some of the light from the Star is prevented from getting to the primary mirror because the secondary mirror is in the way. The secondary mirror casts a shadow on the primary mirror. All reflectors and Schmidt-Cassegrains have some light loss (blocked) because the secondary mirror is in the center of the light path.

[kageypg]

how do you compare reflector and refractor apertures in terms of light-gathering?

[moneebjunior]

I am school Student, I want to make a telescope, you have made a really very good video. It was so much helpful for me. Thanksss

[DeepSkyDan]

@mileyselena7 I'm not aware of a reflector like that. That does not mean there isn't any. I'm not an expert in optics ;-) Not sure of the impact and how it would affect the image quality, but a V shaped Optical Tube Assembly comes to mind where the mirror reflects to the side into the eyepiece instead of directly back up the OTA to the secondary mirror. It would be very awkward to use. The mirror effective surface area would be reduced, same problem. 1 way mirror doesn't reflect light very well.

[lotsofsmarts]

@DeepSkyDan thnk u!