Nexstar 6SE GOTO mount
My name is Malcolm Bird and I have been in the hobby since I was 13....I have owned/used a lot of scopes and mounts, and wanted to post some comments and views on the Nexstar 6SE GOTO mount. As a counterpoint, I have also owned two LX200 mounts in the past and had an abortive marriage with an Ioptron cube – so I am not a GOTO virgin.....
I have said it before in my other reviews, but I’ll repeat it here. I believe that a good sturdy mount is more important than a really good optical tube. Why? Because if you can’t focus your telescope properly, or the image is constantly jiggling around, or you can’t make smooth tracking adjustments to keep your target in view – then the best optics in the world are useless. Your mount is unaffected by seeing, whereas your fancy optics can only perform up to their capability if the seeing, and your mount permits. So you don’t want to put your Takahashi on an EQ1 mount. Extreme perhaps – but it makes the point. Okay – enough of the rant.
What it is.
The Nexstar GOTO series has grown over the years from their humble first attempt at the Nexstar 5i (I had one actually and it was a pretty good 1st attempt) to the current series of Nexstar SE’s and their bigger brothers, the dual fork CPC series.
The 6SE mount is a single fork arm, computerised GOTO altazimuth mount. It may also be used in the equatorial position with a wedge. This is the mount that Celestron uses for both the 6SE and 8SE scopes which are 6” and 8” SCTs respectively.( The 4 and 5SE mount have a shorter fork arm.) The mount and tripod together only weigh 9lbs – so it is a very portable setup.
I have always admired the design of the 6SE series. It is functional and pleasing to the eye. (Compared to the new Meade LS series mount that looks like a bricklayer designed it..)
General functionality and features
The Nexstar mounts come with the ubiquitous Celestron hand controller which, like Meade, gives you GOTO capability to umpteen million targets (most of which you have never heard of and will never be able to see) as well as a host of setup and tuning utilities. It can be upgraded, and controlled via a control cable, although to be honest, I have never attempted this with any of my GOTO mounts. The newer controller features Celestron’s new Sky Align system whereby you point the telescope at three unknown bright object and the scope figures it out from there. More on this later.
The Nexstar SE will run off a series of 8 ‘AA’ batteries (12V) located in a tray in the top of the base. However, unless you know the Duracell Rep personally, and have a flagrant disregard for the environment you won’t want to run the SE mount solely off batteries. You will be lucky if you get more than 2 nights use out of a set of 8. If your SE mount did not come with an AC power adapter - beg, borrow or buy one. Any 12Vdc output adapter will work providing it has the correct 5.5mm diameter center pin positive plug that can deliver about 1000ma.(1A)
A very nice feature of the Nexstar mounts is their ability to mount any scope with a standard Vixen dovetail mount. The ALT (declination) axis has the standard dovetail fixture that accepts a wide variety of OTAs up to a maximum size of an 8” SCT.
This single arm approach trades of some rigidity for the flexibility of accommodating a wide range of OTAs. The other caveat is that whatever scope you mount cannot have any more than about 9-1/2 to 10” from its balance point to furthermost rear component, otherwise you will hit the base of the scope when approaching the zenith.
In contrast, the dual Meade fork mounts do not allow you to dismount the OTA without a great deal of gritting of teeth and possible trauma to the OTA’s paint. Even their new single arm LS mounts have fixed OTAs. (makes you wonder why they didn’t just put this technology in their proven dual fork designs)
A word of caution re: the SE dovetail clamp. The Vixen dovetail system works at fairly shallow angles, and the nature of the Celestron clamp is that it is a little wobbly until tightened up. It is easy to get a false ‘read’ that the rail is fully seated in the dovetail recess when in reality it may be stuck between the upper and lower jaws, only to work loose when you’re not watching. And the mount is so light that it is tricky to push up against the fork firmly enough to ensure proper seating without pushing the mount over. Best to do it in the daylight when you can see what’s going on.
The on-off switch and power jack are located on a small panel at the base of the fork arm which is unfortunately part of the moving portion of the mount. This means that cord wrap can be a nuisance unless you choose the utility function that will not allow the mount to slew past a chosen point before reversing and going round the other way. The power jack is not very a positive fit and you are cautioned (by me, not the manual) to arrange some sort of strain relief for the jack-end to prevent it wiggling loose. If this happens, you will lose your alignment and have to re-align. I just tie the cord around the fork arm and plug it in, or use an elastic band as a strain relief. Sometimes the easiest things are the best..... As an aside, if you leave a set of batteries installed, they will act like a backup, so if your cord does get yanked out, the batteries will take over without a loss of info.
The hand controller is loosely fitted into a recess in the fork arm, which makes it look sleek and modern. However, your natural instinct when carrying the mount is to grab it around the arm, which inevitably sends the controller tumbling. Also, the coiled control cord could do to be longer and more flexible, but there is only so much they could tuck away in that recess. I got used to using the controller with it left mounted in the fork arm. The controller also has a telephone jack port for connecting a communication cable for firmware upgrades or control by a computer based planetarium program.
The tripod is okay, not great, but okay. There is an aluminum (ie: not plastic) tripod spreader with holes for both 1-1/4” and 2” eyepieces and a lower knob to pull it up tight against the legs. It is okay carrying the 6SE but I suspect that a heavier 8” OTA would tax the limits.. There has been enough teeth gnashing lately over manufacturers cheaping out on tripods, that I wished Celestron had put another $1.50 worth of steel into theirs. The base of the mount itself has three flat rubbery pads so you can also use the 6SE mount in a table top setup.
Overall though, the SE mounts are nice looking, well engineered and accommodating of different OTA’s....but how do they work!
These tests were done with a 6SE OTA. This is the same mount that also carries the 8SE.(I have since had the opportunity to try an 8” OTA on this mount, and it is nowhere as steady)
The SE mounts use spur gears instead of worm gears for their final drives. I don’t know enough about the relative merits of either system, but it seems these days, that manufacturers are all relying on smart electronics to make up for the accumulated mechanical tolerances that all gear trains have in them.
The overall mount and tripod is light enough that you can easily carry it outdoors in one piece. Indeed, even with the 6SE OTA mounted, it is still a pretty lightweight setup, so much so, that the whole setup is definitely top heavy with a scope attached. Carrying a spread tripod with a mounted telescope through a hallway and patio doors is sort of like trying to put an armful of skis into the trunk of a car. It’s best done in stages....
Set the tripod up and level, locate the SE mount on the locating center pin and thread the 3 captive thumb bolts from the base into the mount and snug up. Mount your OTA with the previous cautions noted and you’re done.
Once fired up, the controller will ask you what type of alignment procedure you want to use. They are.
Sky Align. Whereby you center the scope on 3 bright objects that you may or may not know the name of, but the Nexstar does, and figures out where it is with this info as well as the time and date which you will be prompted for after selecting an alignment.
Auto Two star. Select and center the first star, and the scope will slew to the second star, which you then center and accept.
Manual 2 star. Select and center both stars manually.
One star – select and center 1 star. (very sensitive to having mount level)
Solar system – can use the moon or even sun as a 1 star alignment. Handy for daytime use!
Once an alignment type is chosen you will be prompted to accept the time date, or ‘Undo’ to correct it. I seem to recall my LX200 classic controller kept track of the time so I didn’t have to input it every time. Not a big deal I suppose, and I guess it saved Celestron an internal lithium battery.
I don’t like the Sky Align. The Nexstar mounts are not fast slewers (5* sec max), and the few times I have tried the Sky Align, it was a slow, tedious process slowly slewing all over the sky for 3 widely spaced objects, made even worse by the fact that sometimes I’d get through the process only to be told that the ‘align was unsuccessful’, or that the `offset was too large.’ Start over.....gnash, gnash....
The auto or manual two star align is relatively quick and simple if you know some star names. The one-star or solar system alignment is great for quick peaks on the brighter objects, where basic tracking is more important than GOTO accuracy.
The hand controller keys are lit with a soft red, although uneven glow. The keys are easy to push.
I know an acquaintance that refers to these mounts as ‘CloseTo’ Mounts, and my experiences bear this out. I have tried every alignment procedure available, and the results have been so-so at best. The Nexstar SE mount seems to be very sensitive to approach directions. When you are centering your alignment stars, it is important that you approach your targets from the same direction that the mount uses when it is performing a GOTO. I found out after several frustrating sessions, that when you go to slew rate 6 or lower, that the controller reverses the direction of the keys........well 6 just happens to be the most useful centering speed for star alignments, and I/the scope was essentially doing the approaches in reverse because I didn’t glean this little tidbit from the manual.....arghhhhhh.
Like all GOTO mounts, a poor initial alignment will give poor results. A bit of extra time spent centering the target stars from the right direction and inputting the accurate time will pay off with more accurate GOTOs. Once a good alignment has been accomplished, the mount tracks quietly. However, objects drift out of the FOV in a few minutes.
For daytime or bright objects where GOTO is not critical, the one star align is great. Just align on the object you want to view and you’re done. Tracking was pretty good even with the tripod plunked down haphazardly.
Slews are quite a bit slower than on my LX200 (5* vs. 8* max), but also a lot quieter. GOTOs are generally somewhere near, or slightly outside the outer FOV of a WA 25mm EP. This is mediocre. With the same care in setup, my past LX200 was more accurate and consistent. The Nexstar seemed to be on and off.
One can debate the relative merits of the Celestron controller vs. the Meade Autostar, but it is sort of like the Ford – Chevy debate, you like what you like. Both get the job done. Both have their quirks, oversights and advantages depending on where you stand. And both have a lot more capability than most of us will ever take advantage off or care to.....
Very light and portable
Good support for up to 6”
Reasonable GOTO performance
Easy to use.
Accepts standard Vixen dovetail scopes up to 8”
Battery or AC driven
Can be bought independently of the OTA.
Tripod on the light side
GOTO performance is finicky
In the end, for me, it is the portability and flexibility of the SE mount that was important. My LX200 was sturdier and arguably more accurate – but the penalty was weight and portability – and of course I was stuck using only one scope........horrors!!!!
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