Celestron C90 Maksutov spotting scope, 90mm, 1.25" 38x, photo tripod mounting block


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This Celestron spotting scope puts good quality Maksutov-Cassegrain optics for long-distance observing (both terrestrial and astronomical) into a compact and lightweight body that's easy to use in the field  . . .
Our Product #: C90M
Celestron Product #: 52268

Product Description

This Celestron spotting scope has:
• 90mm f/13.3 Maksutov-Cassegrain optics
• 45° viewing angle diagonal (eyepiece holder)
• upright/right-reading images suitable for both terrestrial and astronomical use
• 8 x 21mm erect image finderscope
• built-in T-threads for easy 35mm or DSLR camera attachment
• 32mm Plössl eyepiece (38x)

Like all Maksutov optics spotting scopes, such as the ultra-premium Questars, the Celestron C90 is exceptional for observing anything that is small and distant and needs a lot of power to resolve clearly. It provides sharp, high contrast images of distant birds and wildlife, details that are free from the distracting spurious color you'll find in comparably-priced achromatic refractor spotters. Optically very nice, this Celestron 90mm Maksutov has the optical performance to keep you busy observing the land and sky for many years to come.

Features of this Celestron spotting scope . . .

Maksutov-Cassegrain optics: 3.5" (90mm) aperture, 1200mm focal length, f/13.3 multicoated optical system. The 11" long optical tube weighs only 3.1 lbs with finderscope and eyepiece attached.

Multicoated optics: The system's Maksutov corrector lens is fully coated on both sides with multiple layers of antireflection materials for high light transmission and good contrast.

Internal focuser: Focuses by moving the primary mirror fore and aft in the optical tube by means of a large focusing knob on the rear cell.

Close focusing: Twenty turns of the slow, but very precise, focusing knob of the C90 moves the focus from the horizon down to a very close 20'. This is not as great a burden as it might first seem, as only a few turns of the knob in the middle of its rotation range will cover most of the medium to long distance observing situations the C90 is designed for. However, the relatively slow multi-turn focusing makes the C90 more suitable for observing stationary targets from distant locations, rather than trying to follow fast-moving birds in flight.

Erect image eyepiece holder: Unlike conventional 90° star diagonals (eyepiece holders) that reverse the image, the supplied 45° viewing angle erect image 1.25" diagonal provides correctly-oriented images that are identical to what you see with your unaided eye (upright and correctly oriented left-to-right so that printing is correctly oriented and readable and you can easily follow subjects in motion).

Eyepiece: Fully multicoated 1.25" 32mm (38x) Plössl eyepiece with a 1.4° field of view (73' at 1000 yards). While this Celestron C90 Mak has excellent optics with sharp images, its field of view is somewhat narrow, due to the scope's long focal length. However, the narrow field is entirely in keeping with the primary task of the scope, that of long distance observing. The eyepiece has a usable eye relief of 18mm for eyeglass use. In addition, any of nearly 200 different 1.25" astronomical eyepieces can be used with the C90, giving exceptional flexibility in choosing observing magnifications. For example, the optional Celestron 8mm to 24mm zoom eyepiece listed below provides very flexible viewing, with a zoom range of 50x to 150x, allowing you to instantly modify the magnification to suit the target distance and lighting conditions.

Finderscope: 8 x 21mm straight-through crosshair design with erect right-reading images that give you the same image orientation you see with your unaided eye. Three collimating screws let you line up the finder crosshairs precisely with the center of the eyepiece field. The finderscope must be removed from the scope before the scope is stored in its case, but a quick-release dovetail bracket makes removing the finder just a matter of seconds. The finder can be reinstalled on the scope just as quickly, and the dovetail bracket system assures that the finder will be properly lined up with the main optics once in place on the scope. The finderscope eye relief is quite short at 8mm. It will severely vignette the field of view for eyeglass wearers.

Tripod adapter: The scope has a mounting shoe with two standard 1/4"-20 thread mounting holes to let you use it on any suitable heavy duty photo tripod. The front hole is for visual use. The rear hole will help better balance the scope on the tripod when a camera is attached for terrestrial photography.

Built-in camera adapter: The star diagonal holder threaded onto the Cassegrain focus at the rear of the scope has standard T-threads built in that allow you to connect a 35mm or DSLR camera to the scope by simply adding an inexpensive optional T-ring to fit your camera. This converts the C90M to a very high power 1200mm focal length (24x) f/13.3 telephoto lens for long distance terrestrial nature photography. Such high magnification requires the use of a very sturdy photographic tripod for the sharpest images.

Carry case: Nylon backpack style carrying case.

Tech Details

Aperture 3.5"
Armored Yes
Exit Pupil 2.41mm
Eye Relief 18mm
Field of view 1000 yards 73'
Length 11"
Magnification 38x
Near Focus 20'
Photographic Focal Length 1200mm
Photographic Focal Ratio f/13.3
Twilight Factor 58.48
Weight 5 lbs.
Warranty Limited Lifetime


Review by:
For what this scope does, it weighs practically nothing. Celestron is marketing this as a spotting scope which gives you a limited lifetime warranty. I would avoid any of the used ones as Celestron has said this is only for the initial owner. At $150 the $20 you will save on a used one may not be worth it, especially if you need support down the road. (Posted on 1/6/2020)
Review by:
This is a great little scope, inexpensive and quite capable. Granted it is not an 8" or 10" scope but is excellent for a grab and go astronomy scope or for its intended purpose as a spotting scope. I highly recommend it. (Posted on 10/17/2019)
Review by:
Ahhhh the C90, two years ago this was my first telescope, and despite now having 5 telescopes, I plan to keep the C90, and often recommend it as a beginner scope. For someone with a tight budget and mostly interested in observing the planets and/or the moon, this is the best budget scope to get. The optics are great, quality is better than department store toy scopes, and planetary views are much superior than on other budget telescopes such as 114mm reflectors (I also own one), or 60mm achromats. With mine I've seen Saturn's Cassinni division, Jupiter's bands / great red spot / galilean moons, the Martian polar cap, Hellas and several martian maria, the venusian phases, and many of our moon's craters and features. I have even taken some nice pictures with this scope (I wish I could link them in this review!). Being a Maksutov, the C90 has better color correction than inexpensive refractors, less field curvature than SCTs, and less coma than newtonians. Another important advantage is that by being a small/short tube that's lightweight, this scope can do on smaller (less expensive) mounts while still delivering great planetary views. You can expect magnification to easily go up to 125x for the planets, and climb to 140x if sky conditions are good (or planets are close to opposition). On the moon I'd say it tops at 200x.
The caveat is that while you can observe many open clusters with it, in general the C90 is not meant for observing DSOs, so for nebula, globular clusters and galaxies you will want a (much) larger telescope.
Since it comes packaged for use as a daylight/spotting scope (for observing birds, butterflies, boats, etc). You'll need to add a mount. A photo/video tripod will do, but for proper astronomy use you'll eventually want a proper astronomy mount/tripod (I recommend the Exos Nano for this scope), and an astronomy 90º diagonal (I recommend the Celestron 94115-A). As with most telescopes, it doesn't come with many eyepieces (only a 32mm Plössl), so you'll need to get some (I highly recommend the Celestron 8mm-24mm Zoom for this scope).
I own much larger and more powerful scopes than the C90, but on many nights, the convenience, lightweightness and sharpness of the little C90 wins over when I choose what to use. It's a great little scope. (Posted on 11/15/2018)
Review by:
inexpensive, yet capable of observing anything that a more expensive 90mm can do (Posted on 10/6/2018)
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Supplied Accessories

  • Soft case
  • 8 x 21mm erect image finderscope
  • 45° image erecting diagonal and 90° viewing port
  • 32mm 1.25" Plössl eyepiece (38x)
  • Flip-down lens cover
  • Eyepiece holder covers