What’s So Great About Schmidt-Cassegrain Telescopes?

What are the advantages and disadvantages of Schmidt-Cassegrain Telescopes?

They are among the most popular telescopes among amateur astronomers, SCT’s have been around for decades in the commercial market. During this hangout, we’ll discuss some of the advantages of these scopes, why they are so popular, and delve into the many characteristics of their optical design.

Should you buy one? Tune in to find out! Each week Tony Darnell, Adam Smith, John Suffill and Alexander Reinders get together to talk about telescopes and amateur astronomy. You don’t want to miss out on our expertise if you’re new to the hobby and are thinking about buying your first telescope.

Join in our online chat on Discord here:


Marco Aurelio A. says:

What’s up in the sky is a fantastic idea, thank you!

HiddenPalm says:

It’s not clear why Schmidt’s arent for beginners. You can get the Nexstar 6SE for $700. The 6SE bundle that comes with power, filters, lenses, etc is going for $850. And I assume the 4SE would be much less. I guess it requires more maintenance than a Reflector?

Maha Al says:


Maha Al says:


alphaphotoandvideo says:

I’m glad I watched this vídeo, I had the Celestron cs6 ready to buy from Amazon……..
thanks for sharing your knowledge……

bashpr0mpt says:

Am I the only person who finds all optical telescopes to be utterly underwhelming?

Damien Cannane says:

Totally backwards information. SCT’s are fantastic for many types of imaging, particularly planetary imaging and small, faint galaxies and planetary nebulae. But you will need a really nice mount if you’re shootings deep sky targets with one because of the focal length. However, you won’t find an 8″+ system that’s easier to operate. They’re much easier to collimate than Newtonians or RC’s. Aside from turning a few screws, there’s no maintenance.

And SCT’s have a wider FOV than Maksutovs, relative to their aperture.

Joey Murillo says:

Is it normal to have so many cloudy nights during winter? I’ve had just a handful of nights with clear skies in the past 4 months. Finally upgraded my eyepieces and all I can do is stare at them. lol

Art Griggs says:

All optical telescopes are photon catchers.  The larger the diameter, the more photons that are captured – more photons equals better image resolution.  That said, the best things about a Schmidt-Cassegrain (or SCT) are the short length of the optical tube (or OTA) and its lower weight when compared to other designs with the same diameter.  The SCT design enables one to have a larger diameter OTA that is still manageable.  One down side to an SCT is its longer acclamation period (or cool-down) as compared to a refractor.  Another is the weight of a fork-mounted SCT making transport and setup more laborious as Alex remarked.  Personally, I have owned/used pretty much all the mount and optical designs . . . from 60mm to 406mm – reflector/refractor/SCT/MCT et al.  In the end, I realized that the best OTA always seems to be the one I no longer have!  🙂

Maple Flavor says:

the objective maksutov corrector lens focuses all colors to the same convergence point. newtonians inherently have this problem of not having the light properly focused. regular newtonians also require a larger secondary mirror obstructing the primary and further diminishes contrast and the maksutov corrector allows for the secondary mirror to be suspended on it which further improves contrast. the objective maksutov corrector lens uses the spherical errors of a negative lens to correct the opposite errors in a spherical primary mirror.
secondary mirror size: (lower is better)
SCT > DOB > Mak-Newt
mak-newt has much better contrast according to what i’ve read and much cheaper than APOs

Joram Arentved says:

Are there pls. Any Tachyons That can prove to exist?, J.A., Chile, 0056 96 505 67 01, take care, so I can find ‘It,’ The Danish Law, My Semi-ac. Wendy – etc. etc.!

mycarolinaskies says:

1. External crayford focusers eliminate the need to move the primary mirror for focusing
2. It is not typical to remove or move a corrector plate.
3. SCTs are great for imaging DSOs which are typically very small. Matched with at least an APS-C or full frame camera the FOV is reasonable. Undersized chips will crop the field causing some issues for certain targets.

People used to wide-field refractors often dislike the long focal length of SCTs because it does require greater attention to alignment and the details. Yet an 8″-14″ SCT collects considerably more light in a shorter period making the need for numerous subs unnecessary.


Thumbnail has tomorrows date on it. Awesome hangout by the way 🙂

HiddenPalm says:

Hey Tony, your panel should be using Push to talk. And its good that you have Discord, as its the primary voip for gamers right now, and its really the youth youre talking to here since this is all mostly dedicated to beginners. Great job, keep doing it.

HiddenPalm says:

I have spent 3 weeks searching for the perfect telescope …. I was about to get the Nextstar 130 SLT after hours and hours and hours of research, and today I have chosen to go for the NexStar 6SE which is a Schmidt-Cassegrain, with a larger aperture than the 130SLT. But now you guys are saying that a Maksutov is better for astrophotography, which I definitely want to get into …. but telescopes.com is saying that the Nexstar 6SE is both a Maksutov and a Schmidt Cassegrain ….. my brain is so fried at this point. Any words of wisdom? Please dont tell me to get a pair of binoculars. I want to do astrophotography and I want goto. I want! I want! I want! And I want it now! =P

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