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Saturday, June 29, 2013

My Celestron NexStar 5SE Review

My Optical Arsenel
At left you see a composite image showing much of my collection of telescopes. Starting at top left, you see my 60mm Carton refractor, my ETX 90 RA, my  NexStar 5SE, my 6 inch Newtonian, and my Stargazer Steve Dobsonian. Not included are a couple of small refractors.

I show these because they are the telescopes the represent the greatest variety. The favorites of these at the moment are the 60mm refractor and the Newtonian. I have fun with the collection not only because of the range of sizes and portability they provide, but they are each quite different optically. One refractor, one Maksutov Cassegrain, one Schmidt Cassegrain, one Rich Field Newtonian, and one long focus Dobsonian. It is that diversity that gives me enjoyment, with each of the collection offering views with particular characteristics. And, I imagine you can see, none of the instruments are expensive to own.

I purchased the Celestron NexStar 5 SE Telescope  used from an astronomy egroup friend. It hasn't made it's way into "favorite" status yet, but it may well edge out one of the others in that category. Since getting it, I've been using the NexStar side by side with others of my arsenal to see how it measured up. I wanted to find out how good the optics were, and how convenient (or not) the mount was.

The NexStar is a computerized telescope. Once it's aligned, just use the controller to select an object to view. I'm still getting used to it. For years I used a calculator program to tell me where to point my non-computerized telescopes. Now, I use a cell phone and the Star Pointer web site utility. It provides handy computer assist to any telescope, altazimuth or equatorial, that has setting circles.

Optics-wise, with my early trials of the NexStar 5SE I was favorably impressed. While I'm not sure I'm a fan of the GOTO mount just yet, the optics of the telescope are excellent. On early observing trials, I was just using Polaris as an alignment star. Peeking into the eyepiece, I noticed a quite obvious companion of Polaris. The companion I spotted is within the range of a number of my telescopes, yet I'd never noticed it before. The NexStar virtually stabbed me in the eye with the companion.  I was impressed.

On that same evening, I had the opportunity to observe the Plato region of the moon, and it was fortuitously  illuminated for good detail. Again, the NexStar virtually poked me in the eye with the view of about 3 craterlets on the floor of Plato. I've hunted for Plato floor craterlets before with other telescopes, and usually came away without success. But there they were, clearly visible, their impact splashes easy to discern. I looked with my 6 inch f/5 Newtonian, and sure enough it also revealed the craterlets. But, they were not as obvious as when observed through the NexStar.

More recently I decided to do comparisons between each of the telescopes you see in the arsenal by looking at Saturn. I started out one evening by looking with my 6 inch Stargazer Steve DOB. It's especially designed, at f/10, to be a superior lunar and planetary telescope. It has a Pyrex mirror, an over sized tube to help ventilate, a small secondary to minimize diffraction, and a very steady mount.

It showed Saturn superbly. The Cassini division was easy, as was the lighter colored equatorial band around the planet. Also easily detected were 3 of Saturn's moons: Titan, Rhea, and Dione. Stargazer Steve's telescope delivers. The only issue with the telescope is that because of its size, it is a bit more clumsy to use, and it's ultimate capability is usually limited by the atmosphere. It's always a bit of a disappointment when I endure the longer setup time the telescope requires, only to see that on that evening a smaller, easier to set up telescope would have sufficed.

Next I tried the NexStar 5SE on Saturn. To my surprise, the image was nearly as good as the one produced by the planetary DOB. The view was just not quite as bright, with Rhea and Dione a tad more difficult to see. The only other difference is that the Stargazer Steve low center of gravity mount was steadier than the NexStar mount.  But those were about the only differences. Again I was impressed with the optical quality and contrast capability of the NexStar.

The next evening I paired up the NexStar 5SE with my 6 inch f/5 Newtonian. I'd recently bought a Celestron Collimation Eyepiece to more precisely align the optics of the short focus Newtonian. Once I used the collimation eyepiece, I released that probably about 75% of the time, I'd been using a marginally or poorly aligned telescope. With the collimation eyepiece, I knew that the alignment was spot on.

Looking through the Newtonian first, I saw a nice image of Saturn, with the Cassini Division and the same 3 moons easily visible. But when I looked through the NexStar  5SE, the image was even sharper. It was slightly outperforming the short focus 6 inch Newtonian. I was happy with the NexStar, but a bit disappointed that the Newtonian, even with meticulous collimation, had a slightly softer image. None-the-less, the rich field Newtonian still makes a super star telescope.

Saturn Through ETX 90
A few nights later I viewed Saturn with my trusty old ETX 90 (now superseded by the Meade 3514-04-15 ETX MAK 90-Millimeter Telescope), whose images always astound me. The view looked a bit better than the 2012 ETX 90 photo of Saturn shown at left. Other moon and planet photos taken with the remarkable ETX 90 are shown on my ETX 90 Astro-photo web page.

Except for the brighter image that the NexStar 5SE delivers because of its larger aperture, the ETX 90 view of Saturn was surprisingly close. The Cassini Division was easily visible, though not quite as stark as shown in the NexStar, and the same 3 moons were visible. However, seeing Rhea and Dione with the ETX 90 required some time and considerable use of averted vision. A pleasing view, however. Was the NexStar view better? On that evening, just a bit. On evenings with a more cooperative atmosphere, I think the NexStar's potential would be more noticeable.

And finally, I got an opportunity to check out Saturn with the modest sized 60mm refractor. Some of you who jumped into the hobby with larger telescopes than the Venerable 60mm probably think that comparing a 60mm view with the likes of the other telescopes in my collection would be pointless. I beg to differ.

I've looked at Saturn many times over the years, and for awhile I was using an early version 90mm Chinese made Meade refractor. Try as I might with that 90mm, I could never quite make out the Cassini Division. I understand the currently made Chinese refractors are much better, but my early version didn't deliver the quality of images I expected.

But on this Saturn trial, with the excellent Carton 60mm lens at the business end of my telescope, I was able to see the Cassini Division. I could also see the planetary equatorial band, though with less contrast than seen through the bigger telescopes. The view was very nice indeed. As to the moons, I was only able to see Titan for certain, thought it seemed that at times I'd glimpse either Rhea or Dione.

So, what did I learn? The main thing I learned was that the NexStar 5SE has the potential to become one of my workhorse telescopes. The optics are very good, and the computerized mount fairly easy to use, if just a bit shaky. I think the NexStar is a keeper, and hopefully some planetary photos through the NexStar will be forthcoming. For the first summer of use, I struggled a bit with a flaky power switch on the NexStar, but I found that Celestron has a market place for parts, and I was able to find the exact replacement circuit card with the power switch. Now with a new switch, the NexStar works flawlessly.

I also rediscovered what I already knew, that comparing views through different telescopes, especially different types of telescopes, is a real blast. In this little project, I was able to compare views of Saturn not only through some different sized telescopes, but different types as well. The long focus refractor, the Maksutov, the Schmidt Cassegrain, the short focus Newtonian, and the long focus Newtonian each provided a pleasurable viewing experience.

Finally, I learned that both the quality 60mm and the ETX 90, as others have said, run out of light before they run out of image quality. The NexStar 5 SE, like the two 6 inch reflectors, tends to run out of seeing before it runs out of light. But the ease of setting up the NexStar suggests that it's still a great candidate for a first choice grab. It's as easy to set up as any telescope I have, is as portable, and provides excellent performance.

What's left for me to evaluate is whether I can adjust to using the Celestron computerized mount. I'm so used to manually movable telescopes, both altazimuth and equatorial, that having to do all telescope movements through a keypad still seems awkward to me. Now a Celestron 5 inch SCT on an equatorial mount -- that would peak my interest.