Advice re NexStar 6SE

[rblunden]

I've just purchased my first scope - a NexStar 6SE from First Light Optics. I have to say that the advice and service I received from FLO was superb. I will certainly use them again.

I've been able to try the scope out a few times. The Sky Align process has worked exceptionally well - even when there were only three stars visible in the sky when I did the alignment. Last night I was excited to see Jupiter and three of its moons, and also the Andromeda Galaxy. The dew shield, which Steve at FLO advised me to buy, has proved invaluable. The one night I left it off resulted in a totally misted up front lens.

I have experienced two minor problems and would welcome any advice:

1. the glass on the finderscope mists over after a while. Is it ok just to wipe it clear with a clean cloth/tissue, or should I take some other step?

2. Whilst the sky align process works well and I can correctly locate many objects after setting up, it seems to lose its alignment after a time (10 - 15 mins) and has to be set up again. Might this be due to something I am doing (like using the direction keys whilst it is still locked onto an object)?

Any advice welcome. Many thanks.

[MeerkatinBKK]

Hi and first of all welcome to SGL!

You've got a cracking first scope there and should get hours of fun out of it. To address your questions:

1. The red-dot finder that comes with your scope isn't really a high precision piece of optics, so a gentle rub with a lens tissue/cloth will be fine. It might be an idea to fashion a home-made cap out of aluminium foil to slip over the end pointing at the sky when you're outside and not using it. It should help to slow down the onset of dew.

2. Quite a few ways to improve alignment. Here are some off the top of my head, other posters might chime in too:

a ) If you're not already using a power-pack or the mains to power the scope, do so! The Nexstar 6/8SE mount chews AA batteries in minutes and this leads to all sorts of slew errors.

b ) Balance the scope. With the scope off the mount, fit the diagonal, usual eyepiece and your dewshield - ie everything as though you were set to observe. Lay a pencil on a table and rest the scope across it until you find the balance point or centre of gravity. Mark this point on the tube. When you fit the tube back on the mount, make sure this mark aligns with the altitude nut on the fork arm (there's a "V" on the arm to show you this point). A well balanced scope will slew and track much more accurately (and stress the motors less too). Also make sure that the rail on the tube is exactly flush with the mount when you fit it.

c ) A few obvious ones. Make sure the mount is level, and that you've entered in your lat/long and time as precisely as possible.

d ) Try to pick good alignment stars. The first two (assuming you're doing a SkyAlign) should be as far away from each other across the sky as you can manage. The third one should not be on the straight line joining the first two. Don't pick stars too low on the horizon (below say 20 degrees) or ones directly above your head at the zenith.

e ) Make sure the stars are aligned as close to dead centre in the eyepice as you can manage. If you've only got the 25mm eyepiece that came with the SE that can be a challenge. If you've a few higher power ones, gradually switch to higher and higher powers to really nail it in the centre before hitting the alignment button. A few extra minutes doing this will make for a much better alignment. Defocusing the star so it appears larger is also a help when trying to centre it.

f ) When your scope does a slew, you'll notice that it gets roughly into position, pauses, then does a final extra movement. By default, the front of the scope should move down and to the right in this final bit (and this is the recommended setting for the northern hemisphere). If this is the case with your scope, when you're aligning your stars in the eyepiece, you want the final movement you enter on the arrow keys to make the star move right and up. Because of the reversal of the up/down keys at slow slew rates, this means that you'll be wanting to use the right and down keys to centre your stars. If you shoot past the centre, don't worry, just move the star away to the left and below the centre and try again. You'll quickly get good at doing this I promise! This will help eliminate backlash.

g ) You can also fine tune the backlash settings of the mount, but I've found it unnecessary. If you want to investigate further, check out page 21 of your user manual.

OK you should be fairly well aligned by now, however there are a few more steps you can take for even extra accuracy.

a ) Sync. This allows you to improve accuracy for a small portion of the sky. This is under the Alignment menu and gets you to precisely centre whatever object is currently being pointed to (using exactly the same method as when you were doing your initial alignment). Your scope will now have improved accuracy in that area of the sky. If you want to look at something somewhere else, you'll need to "Unsync" first, also under the Alignment menu.

b ) Precise Goto. This is found under the main Menu page. You enter the object you want to look at, and the software automatically finds the nearest bright star and slews to it. You centre that star in the eyepiece as normal, then the scope will do another small slew to the original object you selected. Works a treat!

c ) Update your alignment stars. During the course of an evening it's inevitable that the scope will slowly lose alignment, no matter how good the initial one was. You can however replace one of your initial alignment stars with a new one (rather than do a complete new alignment from scratch), via the Alignment Stars option in the Alignment menu. Full details are on page 16 of the manual, but it's pretty self-explanatory anyway.

Correctly set-up you should be able to keep objects pretty close to the centre of the eyepiece for hours at a time. You don't need to worry about using the direction keys in the meantime.

Phew, rambled on a bit there - once I started I couldn't stop!

Anyway, again welcome to SGL and I hope this helps. Whilst it all seems pretty complicated in the beginning, it will soon become second nature.

Nick

[rblunden]

Many thanks for a very helpful response. There's plenty here for me to do to improve accuracy. I have levelled the scope, entered coordinates , date and time accurately, but will now follow up on your other suggestions. It's strange, but the alignment seems pretty spot on at the start, but soon becomes way off. For example, I was looking at Jupiter (which it found perfectly), went off to look at something else, and about 15 minutes later tried to go to Jupiter again, but the scope pointed way too low. Perhaps ensuring good balance will help with this.

Anyway, thanks again. Plenty for me to do, and I'll report progress.

[rblunden]

Just a quick update. I followed your advice, MeerkatinBKK. In particular I balanced the scope in its mount and aligned down and to the right. In my last session (on Saturday), the alignment sustained for the whole two hours I was out.

Thanks again for the helpful advice.

[MeerkatinBKK]

Hi Roger,

You're more than welcome and glad you're getting the hang of it. Thanks for popping back with the update.

Nick