Celestron NexStar 4SE Review

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Celestron Nexstar 4SE is the smaller brother of the great Schmidt Cassegrain telescope Celestron Nexstar 8SE. If you don’t have a budget for an 8SE, then you should check the 4SE. In this review, I will show you what you can expect from this nice little telescope.

Celestron Nexstar 4SE is a Maksutov Cassegrain telescope with 4inch(102mm) aperture and 52inch(1325mm) focal length. It is mounted on a motorized goto mount. The mount is an alt-azimuth type, but you can also use it as an equatorial with a build-in equatorial wedge. This is a unique feature of this telescope because you have two types of mount in one package.

Celestron Nexstar 4SE Specifications

DesignMaksutov-Cassegrain Catadioptric
Aperture4 inches (102mm)
Focal Length52 inches (1325mm)
F/ratio of the Optical System13
Primary Mirror102mm
Secondary Mirror Spot Size1.25″
Highest Useful Magnification240x ( ~ 6mm eyepiece)
Lowest Useful Magnification15x ( ~ 80mm eyepiece)
Optical Tube Length13.5 inches
Weight of Telescope11 Lbs.
Weight of Tripod10 lbs
PortsRS-232 communication port on hand control
Tracking RatesSidereal, Solar, Lunar and King
Tracking ModesAlt-Az, EQ North & EQ South
Alignment ProceduresSkyAlign, Auto Two-Star, Two-Star, One-Star, Solar System Align
Database25 user defined programmable object. Enhanced information on over 100 objects
Total Object Database38,181

Celestron Nexstar 4SE Maksutov-Cassegrain Design

Most people are mistaken by the looks and think it is a Schmidt Cassegrain(SCT) telescope. But the Celestron Nexstar 4SE is using Maksutov Cassegrain(MAK) telescope design.

The Maksutov Cassegrain design is mostly used in combination with smaller aperture telescopes. It has excellent quality optics, sometimes better than SCT, but because of the thick corrector plate at the front of the telescope tube, it is not used in big telescopes. The plate is expensive to manufacture in big sizes, so SCT design takes over in big Cassegrain telescopes.

If you want to know more about the difference between SCT and MAK design, read my article Schmidt Cassegrain vs. Maksutov Cassegrain.

One of the Catadiaoptric Cassegrain design’s shared advantages is that you can squeeze long focal length into a small telescope tube. This design uses mirrors like a Newtonian telescope. But it is a closed design with a corrector plate at the front, and the secondary mirror on the plate is parallel with the primary mirror.

That’s why the Celestron Nexstar 4SE telescope tube is only 13.5inches(343mm) long but has a focal length of 52inches(1325mm). 

The focuser and the eyepiece are at the back of the telescope because the light reflects between the primary and secondary mirror and then goes through the opening in the center of the primary mirror to the eyepiece in diagonal.

Light path in Maksutov–Cassegrain

The 4SE also has an integrated flip mirror at the back of the telescope. It is used to switch between the diagonal with the eyepiece and the opening for a camera, which you can attach to do some astrophotography. 

The focusing mechanism is also different from basic reflecting and refracting telescopes. Instead of moving the eyepiece with the focuser, the focuser moves the primary mirror to achieve the focus.

Celestron Nexstar 4SE Magnification

Because of the Maksutov Cassegrain design, the 4SE can provide high magnifications. Magnification is calculated by dividing the focal length of the telescope by the focal length of the eyepiece.

Therefore the long focal length of the 4SE is a significant advantage if you are looking for a high magnification telescope to observe planets.

The 4SE comes only with one eyepiece with a focal length of 25mm. It is a Plossl eyepiece providing 55x magnification. It is not a lot, and this telescope can handle higher magnification, so I recommend buying an additional smaller eyepiece for higher magnification.

Don’t forget that the highest useful magnification for the Celestron Nexstar 4SE is 240x, so don’t go lower than 6mm eyepiece.

You can grab a 9mm or 6mm Goldline eyepiece to get higher magnification. 

Also, having a good Barlow lens will double your eyepiece collection and will provide more magnification options with one eyepiece. For example, the 2x Barlow lens will give you 110x magnification with the included 25mm eyepiece and 3x Barlow lens 165x magnification with the same eyepiece.

Here are a dwo examples of magnification and field of view you can expect from different eyepieces with the Celestron Nexstar 4SE looking Saturn:

Jupiter 6mm Eyepiece
Jupiter 9mm Eyepiece

Celestron Nexstar 4SE GoTo Telescope – Motorized Mount

The Celestron motorized mounts are high-quality mounts. The mount is sitting on a sturdy tripod with solid metal legs to provide good telescope stability. 

The database of the mount includes more than 38 000 objects to look at. But to be honest, the 4SE telescope is built mainly for planetary and moon observations. Its aperture and field of view are limiting factors, and many deep-sky objects will not fit in this field of view, or they are very faint to see any details with a 4inch aperture.

However, having a motorized mount is a great feature of this telescope. Just enter the planet you want to see, and it will automatically point to it and keep it in the field of view, tracking it and compensating for the earth’s rotation.

You will have to learn to do the star alignment before every stargazing session, but it is an easy process that you will learn in a few nights. Star alignment has to be done, so tracking and searching for objects feature works.

I have written a detailed guide on how to use a GoTo computerized mount, so go check it out.

The telescope is powered by 8 AA batteries you have to place in a nice hidden battery compartment on the mount. It is a good solution for the telescope’s portability, but I always recommend having a DC power adapter with the motorized mount if possible. 

Even if you are using a DC power cord to power the mount, keep the batteries inside as backup, so if you accidentally trip over the cord and unplug it from the mount, it will not turn off, and you don’t have to do the star alignment all over again.

Celestron Nexstar 4SE Built-In Equatorial Wedge 

The Celestron Nexstar 4SE mount is unique because it has a built-in equatorial wedge to transform the alt-azimuth mount into the equatorial mount. It may sound cool, but frankly, you will probably never use it.

It is complicated to set up, and polar align. It doesn’t have the polar scope, which makes it even harder. You need the equatorial mount for long-exposure astrophotography, which, unfortunately, this telescope and mount are not made for.

And transforming it to an equatorial mount and use it for visual astronomy is just stupid. The factory alt-azimuth setup is more than enough for this telescope.

Using Celestron Nexstar 4SE For Astrophotography

As I said above, even the built-in equatorial wedge will not make this telescope capable of long exposure astrophotography. This telescope is not for you if you are looking for deep sky astrophotography of nebulae and galaxies. Rather go and check my articles about The Best Telescope For Astrophotography or The Best Telescope Mount For Astrophotography to find the right one for you.

Despite this flaw, you can do some astrophotography; at least planetary and moon photography will be no problem. You can attach a DSLR camera at the back of this telescope and do some short videos and capture images of the solar system.

Because of the long focal length, you can capture pretty nice pictures of the Jupiter, Saturn, and the Moon craters. You can also try to use a simple webcam to capture planets(my article), so you don’t need an expensive DSLR camera. 

The equatorial wedge has some use here for planets. If you want to capture a planet rotation in the alt-azimuth configuration of the mount, you will encounter the field rotation. So you can use the equatorial wedge to do that and make an animated GIF of rotating Jupiter with no field rotation in place.

Field rotation is an issue present only with alt-azimuth mounts. Learn more about it here: Altazimuth Mount vs. Equatorial Mount.

Celestron Nexstar 4SE Maintenance

The 4SE doesn’t require almost any maintenance. There is no need to do the collimation like with the reflecting telescopes, even when it uses mirrors. There are collimation screws but don’t do it unless you are an experienced user. You don’t need it at all.

Storing the 4SE is also easy; just follow the basic rules mentioned here: How To Store a Telescope.

Overall this is a maintenance-free, always ready to use telescope. The only thing you have to keep in mind is the corrector plate at the front of the telescope. It will require some temperature acclimatization before use. Just keep it outside for a few minutes before you use it, especially in winter.

Celestron Nexstar 4SE Optional Accessories

I have already mentioned a few optional accessories for this telescope, like the Goldline eyepieces or Barlow lens. I think they are necessary, not optional, to get the most out of the 4SE telescope.

The DC power adapter is also a good idea, but it is optional. You can use this telescope on AA batteries alone with no issues.

I would also replace the red dot finder on this telescope with the proper finder scope or telrad finder scope. The red dot finder is, well, crap toy.

Another cool optional accessory is the Celestron WiFi adapter called Celestron SkyPortal WiFi Module. It will allow you to control your telescope over the WiFi network with your smartphone or computer.

You can learn more about this adapter in my article Celestron SkyPortal WiFi Module Review and Setup.


To sum it all up, if you want a small portable telescope on a computerized mount to look at the planets and take some pictures of the moon, then this is a great little telescope to buy.

But if your budget allows, and you don’t mind bigger and havier scope, buy the higher SE model like 6SE or 8SE, which are much better telescopes. 

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