Celestron C11 SCT 11-Inch Schmidt-Cassegrain Optical Tube

The classic 11-inch SCT for visual observing and astrophotography

The Celestron C11 SCT (C11-A XLT) is one of the most popular large-aperture telescopes ever made, and for good reason. Its 11-inch (279mm) aperture gathers over 1,500 times more light than the unaided eye, yet the Schmidt-Cassegrain design folds a 2800mm focal length into a tube just 24 inches long. That combination makes it a favorite for detailed planetary and lunar views, faint galaxies and nebulae, and serious astrophotography.

This listing is the optical tube assembly (OTA) only, so you can pair it with the mount that suits the way you observe.

Planetary detail and deep-sky reach

At its native f/10, the C11 delivers high-magnification views of Jupiter's cloud belts, Saturn's rings and lunar craters, with a theoretical resolution of 0.42 arcseconds. The 11-inch aperture also pulls in globular clusters, galaxies and nebulae that smaller scopes only hint at. Celestron's StarBright XLT coatings maximize light transmission through the optical system for brighter, higher-contrast images.

Built for imaging: Fastar and HyperStar compatible

The C11 SCT is Fastar compatible. The secondary mirror can be removed and replaced with a HyperStar lens, turning the C11 into a fast f/2 imaging system for wide-field deep-sky astrophotography with short exposures. You can also add Celestron's f/6.3 reducer/corrector for a wider field and faster focal ratio, or image at native f/10 for planets and the Moon. One telescope covers visual observing, planetary imaging and fast deep-sky imaging.

Pair it with a modern mount

Today's strain-wave (harmonic drive) mounts are a great match for the C11: compact, light enough to carry in one trip, and able to handle a large SCT without the bulk of a traditional German equatorial mount.

• ZWO AM7: rated for 44 lbs without counterweights and 66 lbs with them, leaving plenty of capacity for the C11 and a full imaging train.
• Sky-Watcher Wave 150i: a lighter, more portable option rated for 55 lbs with the Wave counterweight kit, and works in both equatorial and alt-az modes.

Plan on using a counterweight with either mount. Strain-wave mounts can carry a lot of weight without one, but a large tube like the C11 puts its center of mass well out from the mount. A counterweight balances the load, reduces strain on the mount and gives smoother tracking. Both mounts accept the C11's included Losmandy-style dovetail.

What's included

• Celestron C11 11" f/10 Schmidt-Cassegrain optical tube with StarBright XLT coatings
• Losmandy-style (CGE) dovetail bar
• 40mm eyepiece (70x)
• 1.25" star diagonal
• 1.25" visual back
• 9x50 finderscope

Celestron C11 SCT FAQ

What mount do I need for the C11?

The tube weighs 27.5 lbs before accessories, so choose a mount with comfortable capacity to spare, especially for imaging. The ZWO AM7 and Sky-Watcher Wave 150i are both good matches. Whichever mount you choose, use a counterweight: even when a strain-wave mount's rating allows the C11 without one, the tube's long center of mass makes the setup much better balanced with a counterweight in place. The included Losmandy-style dovetail fits most mid-size and larger mounts.

C11 or EdgeHD 11?

The EdgeHD 11 adds flat-field optics and mirror locks designed for wide-field imaging with large camera sensors at native focus. The standard C11 costs less and excels at visual observing, planetary imaging and HyperStar imaging, where the HyperStar lens provides its own field correction.

Can I use 2" eyepieces?

Yes. Replace the included 1.25" visual back and diagonal with a 2" SCT visual back and 2" diagonal for wider fields of view with 2" eyepieces.

Specifications