Renewed interest in astronomy.

[JZ]

Over the last few months, my interest in astronomy has been rekindled and am now considering buying a decent telescope. In the past I was limited to a pair of Leitz binoculars and later my 500mm lens for my DSLR. Around 20 years back, I bought my son a 4" reflector for Christmas, but it was cheap, with a flimsy tripod and a drive that only worked if you had the telescope perfectly set on a N-S axis, but we were able to make out the bands of clouds on Jupiter and the rings of Saturn, albeit rather blurry. After reading recommendations and reviews, I am tempted by this Celestron offering, but still open to suggestions, should any be forthcoming. Budget is about £2K including all accessories/software. There used to be a good telescope shop along the road in Frome, MC², but they closed the showroom and went online only, but sadly, no longer appear to be trading. 

[tigerburnie]

Interesting, my brother had one one but not computerised, a fascinating hobby, but I am told I already have way too many to afford another lol.

[PupCam]

On 07/10/2021 at 08:04, JZ said:

Over the last few months, my interest in astronomy has been rekindled and am now considering buying a decent telescope. In the past I was limited to a pair of Leitz binoculars and later my 500mm lens for my DSLR. Around 20 years back, I bought my son a 4" reflector for Christmas, but it was cheap, with a flimsy tripod and a drive that only worked if you had the telescope perfectly set on a N-S axis, but we were able to make out the bands of clouds on Jupiter and the rings of Saturn, albeit rather blurry. After reading recommendations and reviews, I am tempted by this Celestron offering, but still open to suggestions, should any be forthcoming. Budget is about £2K including all accessories/software. There used to be a good telescope shop along the road in Frome, MC², but they closed the showroom and went online only, but sadly, no longer appear to be trading. 

 

Did you ever take the plunge?    If so what did you get and how are you getting on?     Are you doing pure visual or have you put a toe in the complicated, murky waters of astrophotography with the new kit?

 

About 2 years ago, with an initial  budget just over 10% of yours I started as a complete beginner, knowing absolutely nothing, and as a consequence my basic apparatus is very cheap and cheerful - with all that entails.      I bought a Skywatcher 130  with equatorial mount including a single axis (RA) mount.    This choice was more by luck than judgement as I didn't appreciate the benefit of such a mount over a basic Azimuth & Elevation version at the time or indeed the necessity for it for astrophotography.    

 

Over the recent months I've posted quite a lot about my astronomical trials and tribulations over on Early Risers.     @Darlington_Shed requested some details of my astro-camera so I thought it might be an idea to come over onto this thread for a bit more nitty gritty.    I believe many experts suggest you should not attempt astro until you have established a degree of visual skill and suggest waiting for 2 or 3 years.    I have a lot of patience but not for that!

 

For my first attempts at astrophotography I made an adapter for my son's mirror-less Canon camera body.      It's a commercial adapter modified to shorten it by removing the eyepiece mounting and replace it with a sleeve that goes over the eyepiece tube.   This enables focus to be achieved without the aid of a Barlow lens (and hence the inherent magnification).

 

  

 

 

It seemed to work and I had a degree of success with this for both lunar and deep sky images.     Shortly afterwards some of the plastic teeth fell off of the rack for the sloppy plastic focuser.   I became aware of the much improved "Crayford Focuser" design and although you can buy such devices I had a crack at making one.   Here you can see it in place complete with the camera adapter and the manual focus knob.   It's basically an Ali tube sitting in a Vee of four ball races to allow fore & aft movement held in position and driven by a round, sprung loaded rod bearing down and gripping the top of the focus tube.      

 

 

Last year I bought a dedicated astro-camera and despite all of my recent experience with budget equipment I bought a budget colour camera.  It was about £130, which is about as cheap as you can get when astro-cameras typically cost £300+ and many are in 4 figures).    The camera is the AltairAstro GPCAM2 Colour camera and for a tiny, budget camera it sort of works OK for lunar, planetary  and deep sky work but much more of a challenge with deep sky because it's relatively insensitive so seeing what your photographing is much more of a challenge!

 

I've updated the Crayford to a stepper motor drive with an RF remote control so that focus can be achieved without touching the scope - a very big plus point that!    It uses a pair of very cheap 4 channel On/Off RF modules and an Arduino providing the drive signals to the little stepper motor drive board.  At the same time I've added a similar RF remote to the RA control box that came with scope.   In this case the RF module uses a transistor across the back of each button to simulate button presses.     I think Tx/Rx  modules were about £4 a pair and the stepper motor and driver board were equally as cheap.   Here's the updated Crayford with the dinky little GPCAM2 in this case in use with a reasonable 3X Barlow.   The Barlow cost about £100 and is far better than the very cheap and cheerful 2X version bundled with the scope.    A similar quality Celestron eyepiece from the same range has made a big difference too.  IT has much better eye relief which is much appreciated by this spectacle wearer.

 

 

 

And this is the mod to the RA drive box.   You can just about see the RX module standing on end next to the cable entry with the drive wires each leading to a transistor wired across the button connections.

 

 

 

I have learnt that the watchwords with everything related to astronomy on a budget appear to be patience and persistence.     If you buy budget you must put up with quite a lot of frustration which is not because you are necessarily doing anything wrong it's that in many cases the equipment just isn't up to it   e.g. sloppy mounts, wobbly tripods, sloppy focusers and a whole host of other things.   There are of course plenty of things to learn and perfect, particularly polar alignment which is tricky but essential with an equatorial mount (particularly for astrophotography), collimation of Newtonian reflectors and actually just finding the targets (although if you can't find the moon unaided you'd best give up now 🤣).

 

If you are the type of person who tries something and immediately gives up when it doesn't work first time and moves on to something new then astrophotography probably isn't for you but when you do make progress despite and not because of the budget equipment I have to say it's rather pleasing.   

 

So far my really memorable astronomical achievements/moments are:

 

     The first time I looked at the moon through the telescope  - Wow!

     EVERY time I look at Jupiter through the telescope - Wow squared and that doesn't diminish the more times I do it!

     The first time I looked at Pleiades through the telescope

     The first time I got a half decent, sharp image of the moon after getting the hang of some software (Registax IIRC)

     When I finally managed to extract some detail (not a lot I grant you) in the Orion nebula

     My recent exploits and improvements in imaging Jupiter with various software packages

     My first recent wobbly image of Saturn

 

In another post, if anyone's interested, I'll mention some of the other mods and gadgets I've concocted or used and also list some of the software packages I use to process images.  In the meantime I'll leave you with perhaps my best image of Jupiter to date complete with the Great Red Spot and its 4 Galilean moons. 

 

Alan

 

 

 

 

 

 

 

 

 

 

 

 

Edited January 17 by PupCam

[Darlington_Shed]

20 hours ago, PupCam said:

In another post, if anyone's interested, I'll mention some of the other mods and gadgets I've concocted or used and also list some of the software packages I use to process images.

 

Yes please!

[tender]

21 hours ago, PupCam said:

 

In another post, if anyone's interested, I'll mention some of the other mods and gadgets I've concocted or used and also list some of the software packages I use to process images.  In the meantime I'll leave you with perhaps my best image of Jupiter to date complete with the Great Red Spot and its 4 Galilean moons. 

 

Alan

 

 

 

Wow that’s a great photo of Jupiter with the equipment you have. I’ve not ventured into planetary photography as my refactor is only 250mm FL and planets are just tiny dots. I stick with large DSO’s but their faint light brings other challenges with long exposure times and tracking accuracy.

[25kV]

22 hours ago, PupCam said:

In the meantime I'll leave you with perhaps my best image of Jupiter to date complete with the Great Red Spot and its 4 Galilean moons. 

 

Alan

 

 

Somewhat better than my pic of the same this evening!  😉  Got photobombed by our neighbour.

[JZ]

22 hours ago, PupCam said:

 

Did you ever take the plunge?    If so what did you get and how are you getting on?     Are you doing pure visual or have you put a toe in the complicated, murky waters of astrophotography with the new kit?

I bought a Celestron NexStar 8SE. But so far it has seen little use. Purchased with a view too really getting back into it in retirement. That has been put on hold, mainly due the present economic situation and the inept handling of it by this government. But maybe this summer and I will have had enough. I have the base of an old greenhouse in the garden and I plan to fill this with concrete and get some power up there and to use this as my telescope platform. Saw some stunning skies when I visited Australia back at the tail of 2022. Had planned a visit to https://outbackastronomy.com.au/ near Broken Hill, but on the days I was there, the skies were, unfortunately, cloudy. Otherwise, some lovely clear skies. This is a moblie phone shot taken from Coledale, on the NSW coast south of Sydney.

[PupCam]

16 minutes ago, 25kV said:

Somewhat better than my pic of the same this evening!  😉  Got photobombed by our neighbour.

 

I spotted how close they are this evening!

 

It's very clear this evening, I should lug the kit out and have another crack but I'm just too tired.   Never mind.

 

Nice to see some interest in astronomy here though!   😀

[JZ]

17 minutes ago, PupCam said:

 

It's very clear this evening, I should lug the kit out and have another crack but I'm just too tired.   Never mind.

Similar problem. I work earlies, getting up between half 2 at the very earliest, to maybe half 4 at the latest. It means I have to retire between 19:30 and 21:00. In the summer, that means it's still daylight. Roll on retirement.

[PupCam]

Crayford Focuser

 

Going back to the Crayford Focuser briefly.    

 

This little clip of the half-built focuser illustrates the basic principle of operation.    As you can see, its actually very simple.    Unlike a Rack and Pinion  version, as there are no gears there can be no backlash just at the critical point.    The focuser was hewn pretty much completely out of solid aluminium, machining the curved base was a slow job as there was a lot of material to remove but in deference to my venerable old Myford I only took very small cuts!   It's rather chunky and consequently heavy so introduces some scope balancing problems.   If I were making it again I'd do a Colin Chapman (Lotus cars) and try and "Add lightness" wherever possible.

 

The addition of the remote, electric drive was well worth it as it is impossible not to jog the telescope (budget mount don't forget) when doing it manually.    It also has the particularly useful characteristic of being able to focus the scope whilst sitting indoors in the warm 😀

 

These are the little 4 channel RF remote control modules I've used for both the focuser and the RA drive.     Can you believe it?    Five  pairs for £10 !!!!!     They have a multitude of uses including many on a model railway!   Dead easy to use if a little awkward to programme the mode and they work brilliantly

 

 

The electronics for the controller (Arduino Nano, the remote Rx, the stepper motor driver and four rechargeable AAA batteries) live in a little plastic box that has been screwed to the side of the Red Spot finder bracket.  Well it was handy and close by the focuser.     Battery powered means no trailing wire connected to the scope  which is good, but the batteries don't seem to last that long meaning focusing stops when the batteries are flat, which is bad!   There's already a cable going to the scope for the camera (and another if I venture into using the camera's guide output) so perhaps rather than banishing cables to the scope I should just concentrate on good cable management?

 

 

Platform

 

The next improvement to my budget priced scope is an extremely simple one.    A large flat ali plate sandwiched between the tripod and the mount.   This provides a platform to rest my phone on when using a suitable Spirit Level App to set the head level.    I quickly found out the tiny little, stick on, bubble levels are as much use in this application as a chocolate fireguard.   The plate really needs a little guide rail adding to positively set the phone to the telescope's bearing rather than just "Eyeballing" it but that's still on the To Do list.

 

I've recently found a useful little phone App;

 

      "NOAA Magnetic Field Calculator"

 

The primary purpose is to calculate the local magnetic declination but it includes a handy combined Compass and Spirit Level display that works well* with the phone sitting on the platform.     I haven't yet been able to set the telescope bearing accurately enough to magnetic north let alone compensate for the magnetic / true North error!

 

* Well, to be honest the compass bit only works "Wellish" because the magnetometers in the phone can be affected by the big lumps of steel in the mount.   

 

Sloppy Yoke

 

The Sloppy Yoke on my budget priced scope is not conducive to accurate Polar Alignment because as you tighten the locking screw it moves the axis in both azimuth and elevation.   Not a lot but it doesn't have to be a lot.    I was thinking about boring the yoke out and fitting two hunky ball races and a suitably chunky shaft.   So far I've gone with the much simpler interim solution of turning  aluminium bushes to fit in the yoke to take up the slack.  It's a big improvement but really needs the "Proper" solution.   Maybe one day if I don't suddenly decide to splash out and buy a complete new, much better scope and mount!

 

More another day ......

 

Alan

 

 

 

 

 

 

Edited January 18 by PupCam

[4630]

Not sure if photo-competitions are of interest, but the Astronomy Photographer of the Year competition is currently open.  
 

Details here;

 

https://apy.rmg.co.uk/

 

https://www.rmg.co.uk/whats-on/astronomy-photographer-year/competition

 

 

[PupCam]

Further Mount Mods

 

The bearings on the EQ2 mount aren't up to much (like any of it in reality) and after a bit of use the Right Ascension axis was particularly bad which of course is a bit of a problem as that's the axis that tracks.     I disassembled it and measured it up and found I had a couple of ball races that would fit nicely in and then turned up a sleeve to match the original shaft to the bearings.     This shaft had also had a hole bored in the end of it to match the shaft diameter of a an optical shaft encoder (more on that later).     The bearings were held in place in the housing using Loctite Engineering Adhesive and the whole lot re-assembled.    Overall, the head is still closer to a Sow's Ear rather than a Silk Purse but "Every Little Helps" as they say.  

 

  

 

 

Red Spot Finder Mount 

 

These budget scopes tend to come with  a Red Spot Finder (RSF) rather than a proper, optical Finder Scope (either of which are essential if you going to find what you are looking for in the eyepiece) because, yes you've guessed it they are much cheaper .   For those that don't know; the RSF is like a crude head-up display where a little red light dot from an LED is projected onto a small clear screen and once it has been set up (i.e collimated with the telescope's axis) allows you to position the red dot on the object of interest and with a bit of luck the object of interest should then appear in the eyepiece.  Well, that's the theory!    

 

It seems they take a bit of getting used to,  their use is  not helped by the close proximity of the viewing window to the telescopes tube and it can be quite awkward getting in just the right position to see the dot.    A friend kindly 3D printed a taller mounting bracket to get it further from the tube which worked well but .......

 

     ... after getting rather warm one sunny day the nice flat flange turned into a banana.    

 

The bent flange was cut from the upper and lower "lumpy bits"  which were slotted to accept a new flange cut from sheet 3mm aluminium.  The whole thing was then epoxied together and works well.   As mentioned elsewhere,  the new flange later provided a handy mounting point for electronics box for the focuser.

 

 

 

The Astronomy Gadget

 

Early on when I was trying to understand (and failing for quite a long while) how to use an objects RA & DEC coordinates to find them in the sky using the setting circles on the mount.      Perhaps I was being a bit dense (more than likely)  but I hadn't got to grips with the relationship between RA and Hour Angle (the relationship of a specific RA value (e.g. the coordinate of a celestial object) to "time now" where you happen to be.   Whilst the RA of an object doesn't change (to all intents and purposes) it's Hour Angle is constantly changing as the earth rotates.    This all seemed very complicated (well actually it is quite complicated) so I decided to build an Hour Angle calculator (and for those of you who know me you won't be surprised to find it's Arduino based).   The idea being you enter the RA of your chosen object and knowing it's time and position very accurately (it uses a GPS module) it tells you what the Hour Angle is and thus where to point your scope.   

 

The experienced astronomers amongst us will have instantly spotted the problem that the setting circles on cheap telescopes are mere ornaments; they lack the necessary accuracy probably by a couple of orders of magnitude and coupled with all those sloppy bearings, poor clutches/locks mean that you are not going to be onto a winner.   When I'd appreciated that little gem I hit upon the idea of using a couple of optical shaft encoders  These are available quite reasonably (~£20 a piece) and would provide a resolution down to ~0.3 degrees.    OK, still not really good enough but much, much closer and would get you somewhere near so you could start hunting.    So the Hour Angle calculator morphed into the Astronomy gadget which has a couple of displays showing where the scope was actually pointing and where it should be pointing for the OoI.  

 

This was quite a project and try as I might I couldn't do all that was necessary to keep track in real-time of two shaft encoder positions and do all the other stuff (calculating Sidereal time, HA, drive the display etc etc) so it ended up with one Arduino (a UNO IIRC) as the main processor and two Arduino Nanos, one to keep track of RA encoder movement and the other keeping track of the DEC axis using a full compliment of interrupts.   As the encoders provide a relative rather than absolute position you cannot afford to lose track of a single step (~0.3°) - you'll never get it back!    As I mentioned, it's quite well packed in the box with the 3 Arduinos,  the display, the rotary encoder for the control knob, the GPS module and some other little interface modules.     I thought I had photographs of the internals but they seem to have gone walkabouts for now.

 

At about the same time that all this was evolving I was taking my first steps with astrophotography using my son's Canon camera as seen earlier.    It very soon became apparent to this novice that you don't just take one photograph you need to take loads of photographs.   You also don't want to touch the telescope when doing so!    I found out that his camera has an IR remote trigger.   Thanks to the wonders of the internet I found out the IR pulse sequence to trigger a Canon camera.    An IR LED and yet more code was added to the Astronomy Gadget to provide an intervalometer function to trigger the camera.   Sure you can buy such a device ready made but where is the fun in that?    The LED is mounted in a bit of ali tube with a rare earth magnet set in the end so you can just stick it the telescope tube somewhere where the camera sensor can see it.      The software enables you to set the number of exposures, length of and the gap between exposures and also the mode (bulb or triggered).   It worked very well, the only thing to watch out for was to make sure that the time taken for the camera to store each image was less than the set gap between exposures!

 

Here is (almost) the end result

 

 

Funny enough, the gadget has fallen into temporary disuse.   I still haven't mounted the encoders on the mount yet so the pointing system is not yet operational and of course now I've started using the astro-camera  I don't need the intervalometer.  Oh well, never mind.

 

I think that just leaves the "Angle of Dangle" device (actually the polar axis angle indicator) which I'll briefly describe next time and then I'll mention the software I've found, used, rave over, given up on, as appropriate.

 

Alan

 

 

 

 

Edited January 20 by PupCam

[PupCam]

Even More Mount Mods

 

One of the many difficulties I struggle with using the Cheap-O-Scope are the dual purpose tube clamps which hold the tube in the required positions both longitudinally and in roll.     The trouble usually is that having got the scope balanced you then want to look at something which requires it to be pointing in a direction other than horizontal and when you've got it pointing in roughly the right direction you then find you need to be Harry Houdini to use the eyepiece.   So you loosen the clamps until you can rotate the tube at which point it slides down through the clamps aided by gravity which completely mucks up the balance.    Return to the start position, do not pass go, do not collect £200 .......

 

 

So I decided to get a Dovetail bar and clamps so that, once again, I can attempt to separate the two completely separate functions.    After a suitable perusal of various astronomy supplier's websites (most of which list loads of stuff not actually in stock) I resorted to the big A.   I plumped for this rail and these clamps.   I managed to find some suitable if not perfectly correct screws to bolt the clamps to the original head bracket and the rail to the tube clamps.    I have to say first impressions are how much better it is although I still have to add a couple of fixed bands to the tube that will prevent the tube from sliding through the clamps when loosened.   One thing is apparent though and that is the fact that there is not a lot of dovetail on the Arca-Swiss design and it is perfectly easy to undo the clamps sufficiently that would let the whole tube fall out if the orientation happened to be suitable.   That could really spoil one's day (or night!) so I'll have to watch-out for that.   I've got a feeling that the Vixen style has bigger Dovetails and that this may not apply in that case but I couldn't find any sensibly priced 400mm long Vixen bars.

 

 

 

Oh yes the clamps each have a couple of bubble levels built in.   Can't imagine why; they'll never be used perfectly horizontally or vertically so they are as much use as the proverbial chocolate fire guard!  

 

Angle of Dangle Device

 

The AoD device can be seen in the last photograph.   It's the black plastic box stuck onto the RA / Polar axis housing by means of the grey coloured clip (the clip is part of a savagely mutilated  Dyson vacuum cleaner accessory holder - it's the first time it and thus the Dyson vacuum cleaner has been of any use to mankind whatsoever.   You may gather I'm not a fan of Dyson ....

 

Anyway, the AoD device basically measures the angle of the RA axis which, as we know, needs to be set equal to the telescope's latitude  in order to polar align it.    The device is an Arduino connected to a little 3 axis IMU (accelerometers and gyros) module  which it uses to determine the angle of gravity (and thus by inference the AoD).  A tri-colour LED indicates when the axis is pointing too high (Blue = sky), too low (Green = ground) or precisely correct (Red).    The Blue/Green LEDs flashes at an increasing rate as the correct position is reached to give you a clue as to when you are getting close.

 

In order to calibrate it the tripod and mount are positioned  and levelled and the polar alignment is done in the traditional manner.   When this has been done a calibration button is pressed which records the IMU outputs when the position is correct.    The next time the scope is used the tripod is positioned and the mount is levelled.   The axis can then be adjusted to get the AoD gadget LED to show red and Hey Presto the angle should be set.    In practice it gets pretty close but generally requires a tiny bit of fine tuning.    Not unexpected I suppose as the IMU module was cheap and therefore not of the highest instrument grade accuracy or stability!

 

Software next time ....

 

Alan

 

 

 

Edited January 31 by PupCam