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Pros - Replaceable eyepieces - Maksutov-Cassegrain design for premium optics - Integrated T-threads Cons - Complicated design (but that’s the nature of high-quality glass!) - Not waterproof

Welcome to our review of the Celestron C90 Mak Spotting Scope. Celestron is well known for their telescopes, and the C90 Maksutov is designed to be an excellent transition product between telescopes and spotting scopes. It is advertised as being a good choice for both terrestrial and astronomical usage, but how well does it truly perform? Let’s find out.

What Comes With It?

You need to know what you’re getting when you purchase a spotting scope, obviously. The Celestron C90 Maksutov Spotting Scope provides you with everything you need to get started. In the box, you will find:

• The Celestron C90 Maksutov Spotting Scope
• A 32mm eyepiece
• A 45º erect image diagonal
• An 8x21mm erect image finderscope
• Carrying backpack

The backpack is good quality, but does not offer much in the way of padding to protect your investment. If you are going to travel much with this spotting scope, my recommendation would be to invest in a bag or case that offers more cushioning to protect the spotting scope.

How Much Magnification Does the Celestron C90 Maksutov Spotting Scope Provide?

Celestron has designed the C90 Maksutov spotting scope to allow for the use of different eyepieces with varying powers. The included eyepiece is a 32mm Plossl eyepiece, which provides you with 39X magnification. At this magnification, images are very crisp and clear with plenty of contrast and detail. In theory, this spotting scope could go as high as 210X with an appropriate eyepiece, but the most I’ve gone to was 187X with a 6.7mm eyepiece. Testing the spotting scope out at night with that eyepiece allowed me to easily view Saturn’s rings, even though it was a slightly hazy night.

Is the Celestron C90 Maksutov Spotting Scope Easy to Use?

The Celestron C90 Maksutov Spotting Scope contains a very complex system of mirrors and baffles, but it is amazingly simple to use. A single focusing knob controls the position of the primary mirror, which slides back and forth on the primary baffle tube. This focusing knob turns easily and smoothly, but has just enough friction to keep it from moving out of adjustment if you bump it. The placement of the focus knob on the back of the spotting scope takes a bit of getting used to, though.

How’s the Light Gathering Capability on the Spotting Scope?

The 90mm objective lens on the Celestron C90 Maksutov Spotting Scope, along with all of the rest of the optics, are multi-coated but not fully multi-coated. This would typically mean less light transmission than if the optics were fully multi-coated, but it seems to me that this spotting scope already does a fantastic job of gathering light. I’ve been able to use this spotting scope late at night to view stars and planets, even the moons around Jupiter. I’ve also used it during early morning hours to birdwatch, and the images were always bright and clear.

How Are the Optics and Focus on This Spotting Scope?

This catadioptric telescope is a Maksutov-Cassegrain design, combining a spherical mirror with a weakly negative meniscus lens. Of course, Celestron markets this as a spotting scope because of its small size and light weight. But I digress.

The optics are quite good, providing crisp, clear images at all of the magnification levels I have tested it with. The focus knob moves smoothly and easily, but not so easily that you might bump your image out of focus. The included eyepiece is excellent quality, and I quite enjoy the ability to swap in different eyepieces of different focal lengths to increase (or decrease) the magnification. This is more work than just adjusting the zoom, of course, but it yields a much more powerful spotting scope than an all-in-one design would give you.

What’s the Housing Like on the Spotting Scope?

The body of the Celestron C90 Maksutov Spotting Scope is aluminum, and there is no rubber armor encasing the unit. The spotting scope features a dovetail mount for the finderscope as well as a standard tripod mount on the bottom that is drilled for both standard and astronomical tripods. What this means is that you can easily use the Celestron C90 Maksutov Spotting Scope together with a high-quality atronomical tripod for a steady, astounding view of the bright stars and planets.

The eyepiece is removable, and the spotting scope has built-in T-adapter threads for mounting your SLR or digital SLR camera to the device. The optical chamber of the Celestron C90 Maksutov Spotting Scope is nitrogen-filled, so it is fogproof for use in extremely cold weather. This spotting scope is a total of 16 inches long, and weighs 5 pounds.

How Durable is the Celestron C90 Maksutov Spotting Scope?

Make no mistake; this spotting scope was not designed with roughness in mind. The body is aluminum, and there is no rubber armor to protect the spotting scope from bumps or falls. The included backpack offers little to no padding, so if you plan on taking this spotting scope on a hike, I would recommend getting a bag with some cushioning. If you purchase this model, be sure to check your warranty card. Until the end of 2011, Celestron offered a “No Fault Warranty” on all of their binoculars and spotting scopes, which would allow you to have your spotting scope repaired or replaced for a flat rate of $35. According to Celestron’s customer service portal, this warranty is no longer offered, but my unit included the “No Fault Warranty” card even though it was purchased after Celestron stopped offering that warranty. You just might get lucky!