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Thread: Nexstar 5SE Tracking - Am I Expecting too much?

  1. #11
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    Default Re: Nexstar 5SE Tracking - Am I Expecting too much?



    lots of good info so far. I don't have the 5se but do have the 8se so will give a few things to check based on mine but should be same or similar for yours.
    1. did you check balance of the tube when loaded? I made that mistake with mine of balancing mine without the camera attached and it really does make a difference especially on the north/south (up/down) axis.
    2. did you level your tripod really well? A level tripod makes a big difference. I use a small level to make sure I get it really well leveled and it makes tracking much more accurate if you start off as close to exactly level as possible.
    3. did you tighten down all legs and bolts on tripod properly? If anything is loose, it can really cause problems.
    4. IF all else fails... don't ignore just doing an alignment again. I have set my scope up 100s of times over the past couple years and sometimes the alignment just doesn't turn out perfect. I can tell it almost instantly just by moving the scope around in the sky. If it doesn't feel right... I wont hesitate to start over with a new alignment.

    My Nexstar wont track objects for long periods of time without a shift but 30 second exposures are very doable when I do my part with the setup and alignment. One more thought is even the 8se is pretty lightweight which I like but can be a challenge in the wind. Are you having problems even on calm days? It could just be wind influencing your delay pics. IF so, try handing weight under the tripod and see if that helps. That is what I do with my 8SE on windy days and noticeable improvement.

    Ok that's all I can think of but hope you get it sorted out.
    Telescopes: Celestron CPC1100 GPS, Celestron nexstar 8SE
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    Default Re: Nexstar 5SE Tracking - Am I Expecting too much?

    Thanks again for the help and advice.
    I have got familiar with the limitations of Alt/Az (ie, field rotation) but many users report that exposures of up to 30 secs is possible before smearing is visible (in certain parts of the sky). I'd love to get close to that but my limiting factor is sideways drift. I'm trying to figure out if this is normal / to be expected on my Nexstar 5SE (in Alt/Az) or should I be getting better tracking than that. I use a flattener/reducer (0.6) to reduce the focal length to approx 700mm (I've even tried with 2 reducers; one on the camera; one on the scope - just for the hell of it).
    But I always get drift - in the same direction, at the same speed, making exposures of even 5 secs problematic.
    I've checked / adjusted the backlash and done the motor calibration.
    I'm trying to avoid (or maybe just delay!) spending £££ on an EQ mount!
    Should I be able to get 20-30 secs? Or am I wasting my time?

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    Default Re: Nexstar 5SE Tracking - Am I Expecting too much?

    Lots of great advice here. I use a 5SE for (beginning) astrophotography and am indeed able to get 30 second exposures with moderate success. Depending on position and alignment accuracy, I still throw away in the neighborhood of 50% of exposures due to streaking (I'm getting more pick and only keep fully round stars). Don't expect all perfect stars from this mount, but it is still possible. A few thoughts:
    1) Ensure you have menu-> tracking rate:sidereal (if you are indeed imaging stars/DSO's).
    2) Ensure menu-tracking mode is set to your alignment type.
    3) I would suggest using the wedge with EQ alignment (i.e. polar alignment), and use the modified bar mentioned elsewhere in this thread (it may seem intimidating but it is quite easy to mod-- drilling a proper hole is the only real challenge).
    4) Along with 3) above, perform as accurate polar alignment as you can. Practice and more practice, this makes a huge difference because you are not guiding.
    5) Start with 15 second exposures and work up from there to see if you can manage 30 seconds. In my experience 30 seconds is the practical limit of this mount, and even 30 seconds is probably pushing it.
    6) Use a timer/intervalometer or other remote control for the camera shutter. Pressing the button on your DSLR manually WILL cause shakes resulting in streaks.
    7) If you are serious about the hobby, get a 0.63 focal reducer-- this will increase the light (efffectively shortening exposures) as well as widen your view and shorten your effective focal length-- all great things for AP.

    Those are the main things, although you'll surely discover other little tricks as you go!

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    Default Re: Nexstar 5SE Tracking - Am I Expecting too much?

    Thanks again to everyone - and especially TrustyChords.
    That tells me that I should be able to get to something like 20/30 seconds exposure with by 5SE. That's the key info I was after to make me feel like it's worthwhile persevering.
    I do have a reducer/flattener and I have made the modified adjustment bar.
    I will now re-read all the help and advice and practice, then re-read and practice some more!
    Thanks again to everyone and here's hoping for some better weather!

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    Default Re: Nexstar 5SE Tracking - Am I Expecting too much?

    I can't add much to this, but getting some kind of reticule to ensure that the alignment stars are central is essential to good alignment. You might think you have got it central by eye, but it can be very deceptive. Making sure you approach the alignment star from the same direction will make a difference to maintaining the alignment on the object. Take a look at the 'synch' facility in your handset, I find that can give an edge. Starting off with level telescope will also help. There are a lot of myths about alt/az rotation, but it does not prevent exposures 30 sec to a minute, or even longer depending on the part of the sky you are looking at. Stacking dozens or more of multiple exposures can bring out even quite faint objects quite satisfactorily.

    Get the most out of the telescope you have.

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    Default Re: Nexstar 5SE Tracking - Am I Expecting too much?

    I have the Nexstar 127 SLT - had the devil of a time trying to align it until I spent $40 and bought this double-crosshair illuminated reticle 12.5mm eyepiece. Much more precise alignments are now a breeze.

    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    MY procedure - I use Sky Align - align a star in the red dot finder scope. Insert a 25 or 32mm eyepiece in the OTA and get the star centered as best you can visually, remove that EP and insert the 12.5 illuminated one and use the hand control to center the star in the little box the parallel crosshairs create in the eyepiece in the exact center of the scope and press Align. Move on to the next alignment stars and repeat. Done and done.
    Last edited by chicagorandy; 05-30-2019 at 02:00 PM.

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    Default Re: Nexstar 5SE Tracking - Am I Expecting too much?

    The rule of 500 states you divide 500 by the focal length of your lens or scope. This is the longest sub you can take with no tracking before you start to get star trails.
    500 / 2038 = 0.245 seconds (1/25th of a second)

    You have a mount that tracks, so you can get longer images.
    You have an Alt/Az mount, so you can't really do polar alignment unless you add a wedge to your mount. Adding a wedge will decrease the stability of your mount and create other problems. Personally I would not bother with one.
    https://www.celestron.com/blogs/know...n-alt-az-mount

    The things you can do are make sure you scope is well balanced with the camera on it.
    Make sure your hand controller is set to Sidreal tracking.
    If you power your mount by battery, make sure they are fully charged.
    When doing your alignment, use a short focal length/higher power Reticle eyepiece, like this:
    https://agenaastro.com/celestron-1-2...ece-93235.html
    Remove any diagonals when imaging.
    Make sure your Visual back is snug on the SCT and that both thumb screws are snug holding the camera. Basically make sure the camera doesn't move at all in relation to the scope.
    SCT's are notorious for Mirror Flop. To prevent this, do not image up near zenith. Pick an object that is around half way up in the sky to start with.
    Make sure the cables to your camera are free and not snagging on anything.

    Try some shorter exposures, say 10-15 seconds and increase the gain. What counts most is total integration time. This is the length of your sub's times the number of sub's your are stacking.
    So lets say you want to get 90 minutes (5400 seconds) of integration or exposure time, you can do it any one of these ways:
    Total Length Number
    5400 10 540
    5400 15 360
    5400 30 180
    5400 300 18
    5400 600 9

    So 540 subs at 10 seconds will give you roughly the same results as 9 subs at 600 seconds.
    You need to throw away any bad sub's.
    Mounts: EQ1, LXD55, Atlas EQ-G (one with Rowan belt mod, EQ6-Rail and one without)

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