Celestron NexStar 102 SLT Review: Sorry Not Sorry

Celestron NexStar 102 SLT is too expensive for a 102mm optical tube, but the tech is impressive.

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Review

SLT 102 doesn’t come with a built-in battery, and it is not a powerful model. 

But, automation itself can be a reason why SLT 102 is an impressive telescope. 

Let’s take a look.

SLT 102 has impressive tech and slightly boring optics.

Optics

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4mm(3.5″) Aperture

660mm Focal Length

f/6.5

All-Rounder

Celestron NexStar is the usual 102mm refractor that is so common in the “entrance” level telescope market. It has a 660mm optical tube, which creates an f/6.5 focal ratio. 

The optics have all-rounder design.

Such optical design has mid-level performance in both deep space and planetary viewing. Deep space performance is slightly better for a couple of reasons I will talk about, but they are about the same. This is an excellent optical design for first-timers. If only the price tag weren’t this high.

Planetary Performance

Planetary performance is average; enough to view the popular details in the Solar System. 

It can provide images of moons of Jupiter, its clouds, and The Great Red Spot. 

Rings of Saturn is an easy target, and its largest moon Titan is easily visible. The other moons of Saturn are harder to view, but not impossible with the NexStar 102 SLT. 

Mars appears as a red disk with a little surface detail.

Venus is also a disk in, but this time yellow and its phases are observable. 

Other planets; Mercury, Pluto, Neptune, Uranus; are all tiny colorful dots or not observable at all. These objects are hard to observe with any telescope.

The only problem with the planetary performance is the chromatic aberration. Chromatic aberration is a colorful halo around bright objects such as the Moon, Jupiter, and Saturn. Some don’t mind it, and for some, it is a deal-breaker. You can solve this problem with a corrector lens. 

Expect some chromatic aberration.

Deep Space Performance

Deep space performance is better than planetary since chromatic aberration is much less effective, and the field of view is enough to fit in the largest of space objects.

The Andromeda Galaxy, Orion Nebula, Whirlpool Galaxy, Pleiades Star Cluster are always great targets. Most of the Messier Catalog is visible if you are in an ideally dark environment.

Is Astrophotography possible with Celestron NexStar 102 SLT?

The short answer is no. It is not. The long answer is, barely.

Although the mount automatically follows any object in the night sky, it is not built for astrophotography. It uses up and down motions to follow the object, which will ruin any long-exposure image.

But, it is possible to get 30-40 second images. So you can take great photos of the Moon, Jupiter, and Saturn. Deep space astrophotography such as nebulas and galaxies will be disappointing, I’m afraid.

Mount

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No Battery

Reliable Accuracy

Sturdy but Plastic Build

The mount is the most significant part of the NexStar 102 SLT. It is safe to say that most of the cost goes to the mount instead of the optical tube, which is never a good thing, in my opinion.

The mount is more complicated than any manual mount due to its motorized nature. Although it works well %99 of the time, that 1% will introduce problems that you can’t solve on your own. You will have to send the telescope to customer service. So it would be best if you had a Celestron Customer Service in your country.

8 AA Battery Slot

The Battery Problem

The NexStar mount doesn’t come with a built-in battery, which is absolutely ridiculous. You have to get your own AA batteries. This would be acceptable if they didn’t run out in a single night. 

There is no built-in battery in the mount.

In the end, you will have to attach your own power source to the telescope, which will ruin the alignment most of the time, and it will be a burden to carry around. 

Sturdiness

The most important aspect of any mount is its stability. The NexStar Mount is pretty good at that with its large, circular connection to the tripod. 

The 3.75″ dovetail bar connection to the optical tube is not enough to carry heavy DSLR cameras and 2″ eyepieces. But you can simply acquire a new one; they are cheap. 

In terms of sturdiness, Digital NexStar Mount is better than any manual mount that comes with refractors. 

 The Tripod

Although the computerized mount is reasonably stable, the tripod is not strong enough to carry it. It is made of steel, but the legs are not as wide as the usual steel tripod.

Celestron decreased the width to lower the cost; therefore, the tripod is flimsy. It takes a few seconds for the telescope to become stable after any fast movement.

The tripod is not sturdy enough.

Vibration Suppression Pads would largely solve the problem, but it is not a perfect solution.

The Software

There are three options for using the telescope digitally. 

The Hand Controller, which is antique technology.

The SkyPortal App, which only works if you get a Wi-Fi adapter from Amazon for 75$. The connection is not perfectly reliable, though.

Or a third-party app.

Celestron StarSense

Celestron has made StarSense compatible with all of their computerized telescopes. It is an excellent piece of tech that lets you align your telescope automatically, but it is not cheap. It costs almost as much as the telescope itself.

Accessories

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Kellner Eyepieces

Red Dot Finder

Star Diagonal

1.25″ Focuser

There is nothing surprising with the accessories.

The eyepieces that come with the telescope are Kellner models. They are basically second-to-worst models that you can get, after Huygens. Although they are enough to get you started, I recommend getting better eyepieces as soon as you can.

The diagonal is a “Star” model instead of “Amici”. This is absolutely appreciated since Star Diagonals are vastly better in quality and don’t create any image problems with astronomy.

The finder is a “Red Dot” model. It is not the best finder you can get, but you will only use it when first aligning the telescope. It is a good thing that Celestron sends a cheap model to lower the cost. Smart move.

1.25″ Focuser

The focuser is plastic on the outside and metal on the inside. It is a 1.25″ version and has a rack-and-pinion design. It works well for a 102mm refractor, but it does have slight stability issues. Nothing to worry about though, you probably won’t notice it most of the time.

Drawbacks

Expensive

No Battery

Chromatic Aberration

The most significant problem is the price. At this price range, most of the cost goes to the computerized mount instead of the optical tube. Sacrificing image quality for automatization is not a smart thing in astronomy, especially when you can acquire a Zhumell Z8 instead of a 102mm refractor.

There is no built-in battery that comes with the mount, and the AA batteries run out in 5-6 hours.

There is slight color inaccuracy around bright objects.

Conclusion

SLT 102 is amazing automation at moderate powers, and the price tag reflects it. 

There are vastly more powerful options available at this price range, but there is little that can combine portability and GoTo abilities this well.

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