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Nexstar 8 GPS

Posted by Donnie Bigers   10/31/2004 07:00AM

Nexstar 8 GPS

I want to state up front that I have no affiliation with any company mentioned in this article.


I recently picked up a Nexstar 8 GPS used on AstroMart. Although I have only had a few chances to use it, due to weather, I am now ready to offer this mini-review of the scope. Although many might think that a few times is not enough experience to offer a true review, I feel differently. I have been in Astronomy for well over 20 years now. During the course of that time I have owned or used over a dozen SCT's. With that in mind I am also well aware of the drawbacks to the SCT design. Every telescope design has some drawbacks, the SCT has seemingly more. However, the advantages to me far outweigh the bad.

Reason for purchasing

Up front I want to go ahead and list my reasons for choosing an SCT. This particular SCT to be more specific. Anytime I read a review I find it useful to know what the intentions were of the reviewer when purchasing said scope. The only way to understand their opinion is to know what expectations they had going in and what their needs are. First I will start with why I chose an SCT, "again". As I mentioned I have quite a bit of experience with SCT's over the years. I find their combination of reasonably large aperture and small form to be a great advantage. There is not another design commercially available that will give such a relatively large aperture in such a small overall package. Another important consideration for me is budget. Like most amateurs I am on a somewhat strict budget. The strict part comes from the enforcement by my wife. ;-)

Speaking strictly from a financial standpoint, a 10" dob would be a much better value. But I also desire designs that require little effort from me to stay in good working order. I have owned Newts in the past. While I am capable of collimating a Newt, I find it to be necessary more often than a SCT, especially fast Newts. Also, there is a lot more to collimating a Newt than an SCT. Also, a 10" dob although in practice is somewhat easier to setup than an SCT, overall it is more bulky to store and get out of the way. I also require tracking. Early in my Astronomy experience I discovered that being comfortable is a very important consideration in picking a scope. With tracking I do not have to worry about 'nudging' the scope when doing high power work. Though many find this acceptable, I do not. I prefer to sit hands off and simply allow my eyes and body to relax. I have found that not only is it more comfortable, but I often 'see' more when I am comfortable.

The refractor question. Well, to be honest I love refractors. As is quite obvious, they offer more performance per inch of aperture than any other design. However, in satisfying my requirements for portability and reasonably large aperture, they fall short. I owned a 6" refractor a few years ago. While I found that it was a pretty good performer it was large, cumbersome and required an expensive outlay for a suitable mount--if I wanted to be comfortable when using it. Also, chromatic aberration is not something I am fond of. It is a drawback that achromatic refractors suffer from. Unfortunately it is not a drawback that I am willing to live with. Although I often hear that some people find it unobtrusive, stating that they hardly notice it. The problem is that everyone's eyes are different. Depending on what colors the refractor is corrected for, you might not notice it at all. Since your eyes may not be very sensitive to the color that lies outside the infocus spectrum. Whether you notice it or not, it is still there. A quick test with a CCD camera will confirm this. Its not something that I find acceptable. With the 6" that is. I had a 4" achro recently that offered to my eyes very acceptable levels of chromatic aberration. But then again, a 4" scope is not the aperture I want to use. Rather than start a refractor vs reflector war, suffice it to say that everyone is different. With that said, based on my own experience I do not care for achromatic refractors above 4 " in aperture.

The other option is an APO. Now we are talking about a different story. Color correction is wonderful in these scopes. Often they are much faster than a typical achromat, so the portablity factor is closer to being met. However, they are very expensive which moves them very far from my requirements with regard to budget. Also, even if I could afford a 6", the mount required to carry such a beast would be considerable in cost as well.

So it appears that the best option for me is a reflector. An SCT to be specific. I apologize for the long lead in to the review. As I mentioned before, I often find the most useful reviews to be the ones that include what needs the reviewer had and what their expectations were before purchasing the equipment. It is much easier to judge a review when considering these aspects.

What follows is not a critical evaluation of every facet of this scope. I have not encountered any problems since owning this scope. Which says a lot. With that in mind I just wanted to share my experience with regard to this scope and how it fits my needs.

Now on to the review!!

When I purchased this scope I had just sold my Ultima 9.25. While the Ultima was a fine performer, it was starting to see less and less use. It is heavy and requires considerable effort to setup and take down. Before the past year or so this was not a problem. However, my schedule over the past two years has been quite busy. So much so, that I found myself less inclined to go out and observe. So I decided to sell the Ultima and 'downgrade' to something smaller. I really didn't want to go lower than 8". Though a personal preference, it was an important consideration. I had already decided on an SCT based on the criteria I listed above. The most immediate choice was the Nexstar 8i from Celestron. In an effort to maximise my observing time I had also decided that GOTO was something I was interested in as well. From all accounts the 8i provides good tracking and GOTO's, and was also a very lightweight setup. With 8" of aperture it appeared to provide all that I was needing at the time. I had decided that I was going to purchase a new 8i. However, one day while perusing Astromart, as I tend to do a lot, I ran across an ad for a N8GPS. The N8GPS is a different mount than the 8i that offers more stability. Other than that I saw no real advantages to the scope. In fact the increased weight was a concern. GPS as I will mention later was not a consideration. Nor was the carbon fiber tube, other than the fact that it looks cool!

After a day or two of research and brain busting I decided that the N8GPS would be the best choice. If I decided to move up in aperture later or purchase something else, the N8GPS would have more resell value than the 8i. I found the N8GPS for $1300 used. It was approximately one year old and in mint condition. The package also included a flexible dewcap and an 8" dewstrap. Since I already had a controller I would have everything I needed. If I had gone with the 8i I would have had to purchase these items separately. So for a savings of a couple hundred dollars I was able to get the N8GPS used and didn't need to invest in these must have accessories. Must have for my part of the country that is.

The scope arrived in excellent condition. The only thing worthy of mention was a few scuffs on the legs of the tripod, which was pointed out by the previous owner prior to me buying it. The scope was packed in the original Celestron boxes. Just like a kid with a new toy I hurriedly assembled the scope. Like a proud Father I asked my wife to come and look at it. She was impressed as well. Again, since she is usually the financial officer, her approval was a good thing. She noted that it seemed like a lot of scope for the money, especially considering the condition of the scope and the included accessories. I have to agree with her.

Upon assembly I ran into a snag that I think could have been avoided with more thinking on Celestron's behalf. When I went to place the scope on the tripod all was well. Hitting the locating pin on the middle of the tripod was not a problem. Easier than I thought. Harder though, was locating the three holes that the bolts thread into on the base of the scope. I found that I had to get down on my knees to actually line the holes up. This was a problem that I think could be eliminated with a more intelligent design. I decided that with more practice it would become easier. So I took the scope off the tripod and practiced for a bit. It did become easier. But it wasnt until I was mentioning the problem on the CloudyNights forums that I came across an easy solution. Jim Gutman offered this solution.


There's an even easier way. Look at where the power pin and the power switch are located. Notice that there's a rise in between them. Center this over a tripod leg, and the bolts will slip right in. Easier to find in the dark than the little wedges and you can almost do it by feel.

Clear skies,

First light

With that solved. Next came setting everything up outside. With my 'new technique' this was now easy. Surprisingly enough the day the scope arrived it was clear. Unfortunately I had the flu. Not feeling too well, I took the scope out mainly to make sure there was nothing glaringly wrong with the optics and to test the GOTO accuracy. Soon after turning on the scope I was on my way to my first alignment stars. Earlier in the day I had turned on the unit inside the house. It found North even while in the house. Though my location is quite a ways from the original owner, it still managed to initialize from my location--in the house no less.

After aligning on the alignment stars I tried my first GOTO with the Nexstar. This was my first experience with the Nexstar GOTO. My previous GOTO scope was an LX90 a few years ago. There are some differences with the hand controllers for AutoStar and Nexstar. No real functional differences I noted, just different buttons and navigation of the menus. With that in mind I did not take too much time looking at the manual earlier in the day. I can say that if you are reading this review right now, then you have all the computer savvy necessary to operate these types of scopes.

Okay, I pressed the M button on the controller for the Messier catalog. My first target was M22. The teapot is somewhat low from my latitude, but M22 is an object that I am very familiar with. A few seconds later the scope arrived at M22. It was dead center in the eyepiece. I was using a 15mm Plossl, which provided 135x in power. I was pretty impressed at this point. After taking in the view for a bit I decided to try some more GOTO's. Since I was very sick, the GOTO performance was all I wanted to evaluate this first night out. So I went to M13 next. Again, dead center in the field at 135x. At this point I was really starting to feel glad about the purchase. Subsequent GOTO's included a whole slew of Messier objects. Most notably the Dumbell and the Ring Nebula. All the GOTO's over the course of the next hour were dead center in the field. Very satisfying to say the least. Although I only stayed on a couple of objects for more than a few minutes, tracking was great also. To confirm this I went to M57. Then I went inside to take some medicine. I stayed inside for about an hour. While in there I decided I would forego anymore observing and get some rest. So I went back out to take the scope down. M57 was still in the field of view--in fact very close to where it was when I left. Again, this is very impressive and I cant imagine needing better GOTO or tracking performance. Since at this point the scope had been out for a reasonable amount of time I decided to do a star test.

This scope has one of the best star tests I have ever seen from an SCT, actually besting my 9.25. Initially the scope was out of collimation a slight bit. But this was easily solved. After that, the inside and outside of focus images were nearly indistinguishable. The star test looks very close to what a one-fifth wave obstructed scope looks like in Abberrator. Actually somewhere between one-fifth and one-sixth. Now I would imagine that all SCT's dont come with optics this good, but I will say that of the SCT's I have looked through over the past couple of years, both Celestron and Meade are indeed putting out some of their best scopes ever at the moment.

My experience so far with this scope optically has been wonderful. I have not yet had a chance to look at either of the two Gas Giants. I cant wait for the crisp winter nights and the chance to view them and of course Orion too in all their glory. What objects I have viewed so far have been great. This scope takes a bit less time to cool down as compared to the 9.25, which is another plus. Although not a side by side comparison, I can say that from my memory the only advantage the 9.25 has over the 8" is aperture related. Having owned a very nice 9.25 for years I know about all the stories and legends regarding the superiority of the 9.25 to the C11 and of course the C8 as well.

I have not found that to be the case. As I said, any advantage is purely aperture related as far as I can see, which the C11 negates quite handily. I think the reason that the 9.25 is often perceived as being sharper is due to collimation. That's not to say that every time someone says the 9.25 is sharper it is because they are comparing to a C11 that is out of collimation. However, the 9.25 has a longer primary. I have found that "slight" collimation errors that show little detriment in the 9.25 often produce more effect in the "regular" SCT's. When considering the longer primary in the 9.25 design, this certainly seems like a possiblity. I will say that the 9.25 I had was far more tolerant to even slight mis-collimation.

The reason I mention this is that I was afraid after using the 9.25 for so long that I would notice the lack of sharpness in the C8. I can say that I have not experienced that at all. Once I took the time to critically tweak the collimation at a near 'stupid high power', this scope is very sharp and the only thing it gives up to the 9.25 is the extra aperture. Simply put, this is a superb example of what an SCT can be, even with all their drawbacks.

To GOTO or not to GOTO?

Subsequent nights with the scope have been more of the same. With the smaller footprint and the easier setup I find myself using this scope much more often than the Ultima. The GOTO has also added to my enjoyment of the scope as well. Rather than get into the old debate of GOTO vs Non-GOTO I will simply say that I believe this is a hobby of many choices. I used to hear the purists say that people shouldn't rely on GOTO. I refrained from responding because I didn't want to get caught up in a flame ware with them. I dont see the harm. Many of the purist state that by using GOTO newbies never learn the night sky. Well, whether they do or not, is that really an issue? Yes there is something about knowing the night sky in intricate detail. But is it required? I think not. To me, anything that gets you outside and off the couch enjoying the night sky is a plus. If you use GOTO or if you actually cant find a thing withought it means little to me. If you enjoy observing that way, then that's all that matters.

Star hopping is something I used to take great pride in. I find it less rewarding now. My time is very limited. I prefer to spend it actually observing. But even if I still did prefer to star hop, is that the only 'correct' way to pursue this hobby? No. Not at all. As I said, whatever gives you enjoyment in this hobby is what counts. No-one can say that any way of observing is better than the next. It might be better for them, but there is no universally correct way to do anything. If it works for you, that's all that matters. If you spent your whole life observing and only using GOTO, is that wrong? If you never learned the night sky in much detail is that wrong? I think to some it is a challenge to the way they learned. I had similar feelings when GOTO first became widely available. This is my second GOTO scope now. I must say that my feelings after being in this hobby for a while are that everyone does things differently. I personally enjoy the advantages of GOTO. However in the grand scheme I am neither for it nor against it. Everyone can choose which method or style they prefer.

GPS--Overkill to me!!

While I will be the first to admit that I am all for technology, this is something I don't understand at all. As I already mentioned my first GOTO scope was an LX90. I was amazed at how easily it found objects once aligned. When the first GPS scopes were announced I was completely miffed. I thought to myself, how much easier can it be? I mean the GOTO is already doing the hard part for you. Whats next, a scope that takes itself outside and assembles itself? Seriously though, I find the inclusion of GPS on any telescope to be overkill. After spending some time with this one I still have the same feelings.

First off, I can't really take anything away from the telescope and its implementation of GPS. Indeed, it works as advertised and flawlessly at that. What value it is overall is up to each consumer I suppose. Here are my thoughts. When I set my scope up I have to set it on the tripod. How much harder is it to loosen the azimuth and declination clutches? Turn and point it in the general direction of Polaris. Then make sure it is reasonably level. From there the only step I have to do is put in the current time. Takes maybe 30 seconds to a minute longer. But when you consider the time needed for the linkup with the GPS and the time it takes for the scope to move itself to North and level--well the time is not a factor anymore.
Again, I am all for advancing technology, but GPS seems like overkill to me. I can do a two star alignment or an Auto Align in no time. Granted it is an extra "convenience" and it does work flawlessly so far. But it is certainly something I could live without. In fact with the money savings it would be nice if they could include an Ultima eyepiece or an even more useful feature for a lot of SCT owners, the F6.3 corrector.

One of the advantages of GPS I have heard mentioned is if you travel. Well, not sure about everyone else, but when I take a trip anywhere I usually make a checklist. Its much easier to be sure I take everything I need. I do this ahead of time. Also, when I go on a trip its usually not a spur of the moment decision. So I usually know where I am going well ahead of time. It takes 5 seconds to type in the zipcode for where I am going and get a long/lat on the internet.

Considering the stories that I have heard about increased time to link up when using the scope in a much different location, I will take the manual option.

I also hear of people say that they are acquiring their first targets before the other GOTO guys are aligned. Hmm. Well, if 30 seconds to a minute for setup is worth it then by all means have at it. But I know for a fact that I can be setup and going plenty quick enough doing it manually. I have tried. In fact, after using my first GOTO scope a while back I couldn't imagine it being any easier or in fact needing it to be easier. The GOTO feature has already eliminated the hardest part. Now, if it were necessary to do this before each GOTO, then perhaps it might be a bigger issue. But I would imagine that if asked, most users would say that the GPS part of the equation is not a must have, and hopefully for most it wasn't a decision in the buying process.

An even more intesting thing to point out is the recent lawsuit action between Meade and Celestron. As part of the settlement of the Meade vs Celestron litigation, Celestron must now pay Meade $100 for each scope sold that uses the Auto Level and Point North feature. Well, to me it would seem the thing for Celestron to do is to stop offering this feature, since its usefulness in the first place is questionable. Not only would they save money by not having to 'reward' Meade with a $100 royalty, but they could also save money on the GPS feature. Im not sure of the costs of including GPS, but I would think the two combined would allow Celestron to offer these great performing scopes a couple of hundred below Meade. Or they could offer them at the same price point but with extra items. How about a nice Ultima eyepiece or two? Or perhaps the F6.3 reducer, which to me is a much more useful accessory than GPS. Or perhaps a nice 2" diagonal. I could go on, but I think you get the point.


All in all I have found the N8GPS to be a wonderful scope. Meeting every expectation and requirement that I had for this purchase. Which really is all that matters. The scope has allowed me to get out more and to maximise the time when I am out. Although I feel the GPS feature is overhyped, it works as advertised so I cant take anything away for its inclusion. Otherwise the scope works flawlessly. I think it is a bargain for what I paid for it. At its normal price point, considering my modest needs, it probably is more than I need. In that case the 8i would have been a better choice. But, having only paid $1300 I am very pleased as you can probably tell. This was not a real extensive review, which to me says a lot about this model. They do what they say and a lot more. I didn't touch on a lot of things with the telescope. Then again, I have not encountered any problems either, which would make discussing any of the features just a rehash of current advertising.

So, if your needs are close to what I cited early in the review, then by all means I certainly recommend the N8GPS. I can't imagine being more pleased with an astro purchase. It doesn't offer the extreme clarity that a refractor does, but what it does it does very well. Besides, if you are interested in these, then I hope you have done the requisite research and even better, perhaps you have had a chance to use one or two. If so, and you know you want an SCT, this is a very good choice.

Thanks for reading,
Donnie Bigers

Click here for more about the NexStar 8 GPS. -Ed.
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