Review Details

NexStar 4SE Computerized Telescope

Product Review (submitted on February 10, 2012):

Visual Observing.

The 4SE is an excellent telescope for viewing solar system objects. For typical viewing conditions where magnification is limited by atmospherics, it competes very well with a larger C6S for the moon, surface details of Jupiter, and even the trapezium in Orion.

For deep space, its sharp image helps to resolve stars in globular and open star clusters as well as to split double stars providing views that rival larger aperture telescopes. With little exception, nebulae and galaxies are small gray smears of light with no definition as typical in most small aperture telescopes. Its views are much more likely to be appreciated by an experienced observer than by new comer to astronomy.

Astrophotography.

The 4SE mount has a built-in wedge and Celestron’s Any Star Polar Alignment routine to provide for a precise polar alignment. It also has a routine, “Calibrate GOTO,” programmed into the hand controller that will measure and adjust for the impact of adding a heavy load such as a digital single lens reflex camera to the back of the telescope. The Calibrate GOTO command does maintain the accuracy of the 4SE mount and GOTOs with a camera and focal reducer attached to the scope remain accurate. From the perspective of being able to handle the additional weight of a DSLR, the 4SE is capable of photography.

For photography in the Azimuth Mode. The 4SE mount provides a sturdy platform. Exposure times are generally limited by field rotation, not mount movement or vibration. The mount is capable 30 second exposures with a 30% rejection rate due to mount movement, star trailing, vibration, etc. This is more than adequate for very short exposure astrophotography (exposures of 60 seconds or less stacked).

For photography in the Equatorial Mode. Out of the box, the 4SE can not be used in the equatorial mode for astrophotography. The 4SE mount has no mechanisms for the fine adjustment in azimuth or altitude needed to precisely polar align the mount. This is true whether or not a drift alignment is used or Celestron’s Any Star Polar Align. A modified latitude adjustment bar is easily made using hand tools that will allow for a precise polar alignment. If a modified latitude bar is installed, the mount is capable of unguided short exposure astrophotography (60 to 180 second exposures). It is not capable of long exposure guided work.

The 4SE hand controller can control a DSLR. The hand controller can be programmed to photograph up to nine objects controlling the number of exposures, the duration of each exposure, and the delay time between exposures. Once the sequence is started, the process is automatic until all objects in the program have been photographed. The advantages over an interval timer are that exposure times can be varied, and the controller will automatically go to another object once a photograph sequence is completed.

The 4SE is a 102mm f/13 Maksutov Cassegrain Telescope and its high focal ratio is not particularly suited for photography. The typical method to adjust for a high focal ratio telescope by extending exposure time is not available for very short exposure photography with exposures of 60 seconds or less. A 0.63 focal reducer reduces the focal ratio to 8.2, still slow but acceptable. Increasing the number of frames to stack also helps to some extent but the effectiveness of stacking markedly decreases after 200 frames
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Conclusion: The 4SE is ideal as a lightweight grab and go second telescope for astronomers having intermediate and advanced level skills. It has excellent optics and a solid vibration free mount and tripod. For visual work, it can often compete with larger telescopes for solar system objects and does a surprisingly good job for its size in deep space. A 0.63 focal reducer or a 32 mm eyepiece greatly enhances its performance in deep space. With a rather simple modification of its latitude adjustment bar, it can serve as a lightweight, portable equatorial platform to photograph the brighter deep space objects; however, its f/13 focal ratio detracts from its ability as a camera telescope unless a focal reducer is used. While the 4SE is more appropriate for astronomers with intermediate or advanced level skills, it is also a excellent choice for a beginner who wishes to explore the many aspects of amateur astronomy before purchasing a larger and more expensive telescope. It is ideal where portability is paramount and a photographic capability is also desired.