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Frustrated with new 6" SCT


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I have been playing with my new Celestron nexstar 6" SCT and I can't be more frustrated...views of moon and Jupiter are good, but these are pretty much all the objects I have been able to observe. Am I suppose to be able to see the Orion nebula and other DSO's?....or is it not a big enough telescope?. My son has a 4.5" newtonian (powerseeker 114EQ) and he can pretty much see the same two objects (barely distinguishing jupiter's bands).

I've invested countless hours aligning the scope, making sure the tripod is leveled on solid ground ( i use a stanley level with three bubbles)...follow other people's recommendations when centering the alignment stars, got a decent Celestron zoom eyepiece and other accesories ( power tank, 2x barlow, dew shield, etc)....still not big advantage over what my son can observe with his $160 newtonian.

Goto functionality is pretty much useless...it misses the mark unless it slews to an object it has been previously "sync" to ( like jupiter)...tried star re-alignment multiple times until it slews to the star spot on, but still misses targets like Jupiter itself slewing to it completely out of the FOV ( two star alignment seems to work better than sky align). Scope seems to be collimated ( star pattern is concentric when out of focus).

I've noticed though they shipped to me an older version of the scope ( version 4), not the latest nexstar +...so I called them and they are sending me a replacement.

Do I give it another chance with the new scope I will receive ( same model, hopefully latest revision)...?...or do I just send it back unopened and try a different model/brand?.

Any comments are appreciated...thanks...

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Mgarsal............Hi, That's not good news that your having problems with the telescope. The fact that they are sending a replacement, could they just not send back a refund? That said, someone here will have the same scope as you , and will no doubt be able to help you. I personally haven't used a GoTo (go-near) telescope system for the exact problems your having to suffer. I know about GEM/EQ mounts and just think there's too much to adjust all the time. As you can see from my signature. I have a Newtonian telescope on a Dobsonian mount. If your interest is solely observation, then I would recommend a similar scope  for your next purchase.

EDIT* I still have a Celestron 127 EQ and my Skyliner blows it away with its performance. What you can see also depends on your skies, light pollution, weather ect. Maybe send back the Nexstar and negotiate a replacement Dobsonian. Its the easiest thing to use, just place on level ground and you can start straight away on low power, but may need to cool the telescope to ambient temperatures before going to higher magnifications. Using High mag  early allows you to see the thermal currents in the tube, Once the scope is cooled, all is fine.

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I use the 8SE OTA but upgraded my mount - didn't get on with the SE mount due to wobble and lack of accuracy, nothing I could do would get it to find objects.  You have enough OTA to see the orion nebula for sure, as well as a number of other DSOs.  There are people however that do have success with that mount so it is worth persevering UNLESS you can find the money to get a full refund and add a little to it to get the 8" or 6" SCT on the AVX mount - would be a far more effective set up.

Since I changed my mount it is amazing how much more I see, and how accurate the go to can be

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Hi Mgarsal and welcome to SGL :)

Unless you have a faulty model the Celestron mounts are usually pretty accurate with "goto" and tracking in my experience - I've had three of them with no issue. But I have seen people having problems with them and it's nearly always "user misunderstanding" of some kind or other.

The 6SE has a 1500mm focal length and comes with a 25mm eyepiece giving 60x magnification at f-10. This is quite a low magnification which won't give particularly high accuracy. I like to work around 150x to 200x magnification on average for alignment, which in your scope would mean using eyepieces in the range of 8mm-10mm.

Centering is particularly important during star alignment and the finder and main scope must be perfectly aligned with each other. During daylight - focus a 10mm eyepiece on a distant object over a mile away - something like a pylon tip or church spire tip. Get the tip of your object dead center of the view and then adjust the finder so the cross hairs are exactly on the same point.

When doing a star alignment - first ensure you know which star(s) you're pointing at - you need to be able to identify them exactly by eye and totally unaided. Expect to have to adjust the first two stars in the alignment process by centering first in the finder and then in the eyepiece (the software will guide you through this). Do it using a 10mm eyepiece - you should find the 3rd star to be be bang on. Once you've finished aligning all should be well for the rest of the session. Initially choose alignment stars in the same quarter of the sky for best results. Get a well spread triangle of stars in that area - eg winter triangle or summer triangle.

If you're out all night then expect to have to periodically recenter occasional objects that appear slightly off after a slew - particularly if you're hopping all over the sky. After recentering half a dozen objects well spread around the sky the goto accuracy will come "on song" as the software builds in successive adjustments to it's star map.

Because the sky moves naturally in equatorial mode - alt/az mounts often need a little "training" to keep up. It just needs a little patience for an hour or so to get it right. Also bear in mind that an Sct fov isn't as wide as say a newtonian or some refractors - so using a higher power eyepiece up to 200x will improve accuracy immensely - any lower powers will automatically be accurate by default.

Hope that helps and do come back if you're still stuck with more questions. :)

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I have the 127 SLT so similar type of scope but less aperture. In my limited experience and based on research before buying;

I would not expect DSOs to be much better than your son's newtonian. I do not think DSOs are an SCTs strength but you should still get reasonable views. I have been happy with what I have seen over the last 7 months although I do pick my targets carefully, which include the Orion nebula. Have you read Qualia's thread pinned at the top of this forum ?

On the GOTO side of things I find it has been very good/excellent most of the time, so unless you have a software glitch or hardware malfunction I am surprised by your problems. fwiw I normally use two star align. Sorry to state the obvious but check and recheck your settings; Lat, Long, time, zone and date. eg it is easy to change the Lat and Long when on a remote site and then forget to change back. As you are using a power tank that should cover the most common problem with goto, the power supply.

I hope things sort themselves out.

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Well, there is definitely enough aperture for you to see the Orion Nebula - I can see it as a clear fuzzy patch with my 8x40 binoculars. I'd wait and see on whether or not the replacement solves the problem. You didn't mention Polar Aligning, which presumably you've done accurately?

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SCTs can easily do DSO work - it is just down to aperture, a 6" should show a lot in the right sky conditions.  The main limiting factor is the FOV for the bigger ones - but I easily pick up galaxies, nebula, etc.

An no PA required on the SE mounts

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What brantuk and stevend said bssically. When I had my goto sct the only really bad time I had was power tank related (lack of charge) although at first I also had accurasy issues and this was down to centering using to big an eyepiece.

Does your son not have a 10mm you can borrowvto centre it. In absence of that you could always barlow the 25mm. I always used 3 star align and never had any issues after the initial teething.

until I got aperture fever that is, hehe

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Have the 5" version of your scope and love it. You'll see plenty of DSO in your 6". Alignment is usually accurate for me and without issue.

Think the Nexstar SE range a great blend of portability vs aperture.

Hope that you find the replacement works straight out of the box for you.

Take your time in the set up, use the latitude and longitude for your location, date in US format, a decent power supply, and on level ground you should be fine.

Best of luck.

Chris

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Thanks much for the feedback and recommendations.

I've noticed that out of all the settings the correct time needs to be entered every time I try a new alignment procedure ( same night)...I have not kept a record but sometimes time is close to my last entry, off by 20-30 minutes or more....wondering if this is normal ( all other settings like long/lat, date, time zone, etc are correct and kept even between power cycles/different days as it is likely stored in NVRAM). If the hand computer needs less than 2 minutes of time error...could this affect the alignment procedure?...it usually takes me at least 15 minutes to do a two star alignment while I locate a good star, find the name, align to it, slew to the 2nd star, etc. The hand control must have a little VCXO oscillator that should be able to keep reasonable time ( to miliseconds a day) unless powered down.

Comments appreciated...

I'm curious whether the new scope would do the same thing...I'll give it a try and report back. If not satisfied I'll probably send it back and save for a VX mounted scope as Paul recommends. As Chris says I like the versatility the 6SE promises and would like to keep it.K

Brantuk, Knobby thanks for the advice...for now I've been using my zoom eyepiece at higher magnifications and de-focus so my alignment stars are dead center in the FOV ( reticle eyepice and Telrad sight ordered!)....and use the hand control in my hands so I don't touch the mount/scope. My long/lat are good to the second, verified by two different types of services, and I'm sure the stars are correct ( Star walk/IPAD is my aid)...I do not use planets. Time is checked against a service sincronized to a NTP server...entered to the second.

Only way I get it to track correctly is by one object solar/planetary alignment with jupiter...I use this out of my window sometimes when I don't have stars in sight ( it goes back to jupiter mostly dead center in the FOV), but this method is specified to have limited accuracy so not good to go find other objects....Not failing because there is no time error accumulation vs other procedures??....

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The inaccurate clock in the mount will create great difficulty in alignment.

The Earth rotate 360 degrees in 24 hours, i.e. 15 degrees in one hour, or 7.5 degrees in 30 minutes.

With your stock 25mm eyepiece in focuser, you have hardly 1 degree true field of view, that error of 7.5 degrees will make the object way out of the view.

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The aperture issue is straightforward - a 6" scope will give better DSO views than a 4.5" scope, assuming they have equally good optics. The issue is finding the objects and keeping them in view, i.e. the mount. That comes down to two things - what you are trying to do, and personal taste.

As a dedicated dob user, personally I find GOTO (and EQ mounts) more trouble than they're worth. My dad got a second-hand small refractor on GOTO mount. We spent ages trying to get the GOTO to work - in the end I switched the thing off, loosened the clutches and used it as an undriven alt-az, which made everything simple. Recently a friend wanted me to help them set up their small EQ mounted Newtonian. I did this no bother, but then spent ages trying to get the thing pointing at Jupiter (using the supplied and completely lousy Telrad-type finder attached to the scope). I also managed the Moon, but trying to get the thing pointing at the Orion nebula was out of the question - I'll give my friend a spare 30mm finder I've got, and that will make his life easier. Seeing the nebula through his binoculars, by the way, was no problem.

With any scope, you've just got to get used to using it. I'd say the learning curve is easiest with any undriven alt-az mounted scope (e.g. a dob) but if the advantages of GOTO or EQ are desired then it's a case of learning the ropes. I'm sure the Nexstar 6 is wonderful once you've got the hang of it. But if you can't, then I would suggest putting a finder on it, mounting it on an alt-az tripod, and using a map.

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it usually takes me at least 15 minutes to do a two star alignment while I locate a good star, find the name, align to it, slew to the 2nd star, etc.

15 mins is a long time to set up. I suggest;

- before you start choose two stars (use stellarium or a mobile app like google skymaps to help if required)

- now BEFORE selecting SkyAlign etc, move the scope around to your first star (ie to reduce set up time)

- now go into setup mode being able to set the first star quickly, then do the second

That is how I do it, as I find speeding up the setup like this makes a difference to accuracy.

HTH

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Agree with Stevend - 15 mins is too long. The scope will "remember" your date and the latitude etc, but not the time. Each time I align at the same site, I only have to update the date and time - the handset  / controller does not "store" these; but is not / should not be an issue.

I rarely use the sky align, which uses any three bright objects and usually use the auto two star align - if out early enough, Vega in the West and Capella high up and I'm usually away.  If I am looking for a really tough (for the size of aperture) target, will swap the supplied 25 eyepiece out for a 13mm for the fine align....but not always.

I liken learning to use GoTo as like learning to change gear in a car - the first times you sweat and crunch them, but with practice, you soon do it without any hassles.

One other tip, if you have a local astro club near you, you can bet that one of their members will have used the same mount or scope etc and would am sure be happy to give you a few pointers?

Good luck, the 6SE is a great scope.

Chris

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According to Michael Swanson's 'bible' on the NexStar it doesn't matter how long you take to align the scope.  Yes - you have to update the time and date every time you switch on but once you have started that procedure it remembers it and takes account of everything whilst you have it switched on.  What does help with GOTO accuracy is the centering and, if you use the Hibernate facility, to use the same clock/watch every time.

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Thanks, just to be clear, my experience with the 6SE scope is that it is not retaining the time during the same session...(no power cycles)...time is off 20-30 minutes or more between each alignment attempt ( date is kept, but time needs to be adjusted)...please provide your experience on this ( cjg?).

Unless some internal process...I do not think this is normal as time will be drifting greatly during the star alignment process...

This is different from setting time/date each different day out with the scope...as expected.

Thanks again for the help.

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Thanks, just to be clear, my experience with the 6SE scope is that it is not retaining the time during the same session...(no power cycles)...time is off 20-30 minutes or more between each alignment attempt ( date is kept, but time needs to be adjusted)...please provide your experience on this ( cjg?).

Unless some internal process...I do not think this is normal as time will be drifting greatly during the star alignment process...

This is different from setting time/date each different day out with the scope...as expected.

Thanks again for the help.

Good morning Mgarsal,

this is my experience too if I have to for whatever to reason realign the scope during an observing session (usually because I've knocked the tripod) the handset shows the time I initially entered at the start of the evening - makes no difference though as the scope still tracks and aligns to targets without a problem during the session - think that the time must be stored in some manner  / format elswhere; so would say that this is normal.

Chris

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According to Michael Swanson's 'bible' on the NexStar it doesn't matter how long you take to align the scope. 

In my experience, since I 'speeded up' my alignment technique I have found the GOTO to be more accurate - just an observation. I also agree on the importance of centering and using a med/high power EP rather than say the 25mm.

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My understanding is that if you have to restart the alignment procedure then the time will be when you first started, but during the actual alignment it does retain the time.  To quote from Michael Swanson's book, Myth 1 - You must work as fast as possible between centering the first and second Alignment stars.  Sounds good, just isn't true.  In a test of this statement I started an alignment, centered the first star then waited one hour before centering the second star.  This caused no problems; Goto and tracking behaved normally.  Obviously the hand control keeps track of the amount of time between centering one star and the next and incorporates it into its calculations.

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i may be wrong but on the HEQ5 pro I've come to conclude the handset time only gets you two things.

a) polaris hour angle (irrelevant on alt-az as can not be polar aligned)

B) approximate slewing to first chosen star during star alignment (I always do 3-star alignment, more accurate than 2 star).

I suppose if you skip star alignment then time would give the mount the best chance to slew around and goto, but it would never be that great.

FWIW the Shywatcher EQ goto mounts don't keep time or date either, there is no built in-clock, they just show the last entered value on initialisation - I set mine to nearest minute from time-sync'd phone on start-up.

Silly point but be careful to star align on the right stars too, very easy to be out and not realise sometimes :)

Good luck!

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I cannot add much to what has already been said as there is a lot of useful information and tips there.

Just to say that I also have a Nexstar se 6 and have learnt that taking a little time and effort to ensure that the tripod is level, the date time etc are accurate and to align using a low then high power ep pays dividends. The only other consideration is then to remember where the power cable is so that you don't remove it from its socket 10 mins into a session resulting in having to go through the process again.

Hope you persevere with it, its a great scope and the quality of the optics is exceptional.

RK

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Not sure if I have missed the point here, but have you ever seen a bright Deep Sky Object through either scope? If not, then why not try using the finderscope (I assume the scope has one) to locate a bright DSO such as the Orion nebula. At least you can be sure the scope is up to it before you start to worry about the GOTO mount??

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