Avocette

You may find some help here also: https://www.cloudynights.com/topic/683609-polar-alignment-how-good-is-good-nuff/#entry9766007

Super job! Could you let us know more about your equipment, filter(s), subs exposure and number please? And processing software etc? Many thanks.

Curious to know whether you feel any significant backlash in the drive gearing? My own AZ-EQ5 was 2 years old when I bought it and had a bit of slop about equal in both axes until I tweaked them (and lightly greased them). Very happy now. The Alt scale is just a piece of printed black self adhesive tape several mm from the pointer, so may suffer from being inaccurately placed. However if you put the head in AZ mode, which is rather accurately preset in the factory, the pointer should indicate 90° which will give you a clear idea of the likely error in the tape scale position.

In (simple) answer to your question, the primary mirror locking screws are the grub screws which are reached with a small Allen key type wrench, the adjustment screws are the cross head screws. For the secondary mirror, the adjustment screws are also grub screws requiring an Allen key. The cross head bolt in the centre of the secondary mirror fitting, holds the mirror against the pressure from the adjustment grub screws, so will need careful adjustment at the same time. However, are you sure that you need to make ANY adjustment at all? Although the scope is an earlier model, the primary adjustment screws look just like my Skyliner 200p did in 2012. Behind the adjustment screws are neoprene O rings which after years may have lost their elasticity having been effectively ‘crushed’ during factory collimation. Even when new these O rings permit very little adjustment but good manufacturing tolerances probably make this approach adequate for most scopes. If you do start making adjustments you may well need at least replace the O rings with fresh ones, or better, change the adjustment screws and locking grub screws to longer ones and use small springs in place of the O rings. Then you could also spend on Bob’s knobs (which I ended up doing) for easy tool free adjustment. But this will mean that you cannot stand your scope (temporarily) on the bottom end of the tube without risking affecting the collimation.

I have just come across this thread again after a couple of months and thought I would update you to today’s situation in my particular Pi4 implementation. I am now using a 2GB RPi4 in a Flirc aluminium case which acts as a CPU heat sink and keeps the processor below 50°C indoors and below 40°C outdoors. My plate solving for Polar Alignment and more generally is now sorted. I did not need all of the astrometry files that I had downloaded due to an error in calculating the FOV (so my initial installation now occupies about half of the 32GB micro SD card). It turns out to be less error prone to let Ekos measure the FOV for itself by performing a first ‘Capture and Solve’ in the Alignment module before attempting Polar Alignment. Solving typically takes 10 seconds with my Canon 450D and 15 seconds with my 550D, I suppose due to the larger number of stars which are captured by the 550D sensor. I am very impressed with the practicality of the whole system and some early imaging in Bortle 5 skies with nearby yellow streetlamps and the full Moon bathing my back garden in light. I am now planning to have my 550D astromodified, to invest in guidescope and guide camera and very likely in one of the multi narrow band filters. With some regret I decided to fund these by selling my little used Dob.......

I recently bought my AZ-EQ5 second-hand technically still under two year guarantee. I found a touch of backlash on both axes - about equal on each. Rather than ask the dealer to honour the guarantee and argue about whether the level of backlash was abnormal, I had a successful go at making adjustments myself. Not difficult, but not for the faint hearted. Obviously a new mount bought from a reputable dealer like our sponsor, shouldn’t have significant backlash, but I sometimes question the factory quality control. For instance, the printed tape sticker which shows the latitude angle for the Alt adjustment, is about 5° out! On your second point the Delux pier style tripod has definitely been withdrawn from the market, but whether that signals the demise of the whole mount I don’t know. I feel lucky to have bought my AZ-EQ5 with the pier style tripod, admittedly already fitted with a pillar extension to bring it to a very useful height. And I am very happy with the wide range of adjustment on the Az axis (around +/- 25°) and the simple single spring loaded lever adjustment on the Alt axis (very effective and no risk of bending adjustment bolts).

My friend and I are still scratching our heads for ways of making it possible for one observer to use both scopes...

It’s early days for me with my newly acquired AZ-EQ5. I can feel a little backlash, about equal in both axes, and that does mean a touch of horizontal slop in AZ mode. Last night was my proper first light in AZ mode where I wanted to compare my ‘old’ SkyMax 150 Pro with a friends much newer one. We set up the two scopes in parallel and I was happy that the views through my one were no better and no worse that through his (using matched pairs of eyepieces). I did a quick levelling of the pillar top before attaching the head and carrying out a two star alignment. After that we toured the sky with a 20mm Maxvision 68° eyepiece in my scope and a 4.7mm 82° in his. We were amazed how well the two scopes were aligned naturally on their standard dovetails in pucks which have differential adjustment only in the Alt direction. But the AZ backlash didn’t bother us and the GoTos were spot on, often in the centre of the 4.7mm I.e. at ~380x. My major application of the mount will be AP in EQ mode, when a little unbalance should bias the backlash, but it was great using AZ mode - and a touch of backlash in the AZ axis in visual use didn’t worry me as a long term Dob nudger. I shall be reading up on everyone’s experience in attempting to minimise backlash in both axes on the AZ-EQ5, but last night’s experience was great and may have sold another AZ-EQ5 to my friend.

That's the same setup that I have with RPi4 4GB running Raspian Buster, KStars, Ekos and Indi. I run it 'headless' I.e. without monitor, keyboard or mouse attached, but controlled via VNC on an iPad. The specific package I installed on my RPi used the AstroPi3 script written by Rob Lancaster (search rlancaste on www.github.com) who has been preparing versions to run on various other OSs if you don't like Raspian. I'm no Linux expert so I have needed step by step instructions but Rob has provided these in his Readme.txt. I have a Ublox 7 gps dongle, an EQDir EQMod cable and my Canon DSLR connected by USB, so the KStars knows where it is and the correct time when operating in hotspot WiFi mode in the field. My 'experiments' with the whole rig over the last few nights have been to try to become familiar with the myriad software packages especially starting with Polar Alignment (I have no polar scope on my AZ-EQ5). No resounding success so far, but maybe better news tonight having downloaded and installed a further 12GB of astrometry.net Index files today. This means that my RPi microSD card now has about 28GB onboard! Plate solving of some images I photographed last night has been working offline on the RPi with a typical delay of a little over a minute so sounds like things may work tonight.

I sympathise greatly with you -philip- having myself explored various telescope options over the last seven or eight years. My budget didn’t stretch to buying new, so my purchases were largely steered by local second hand availability and a bit of luck. As my signature suggests I presently have assembled an array of four scopes, a 300mm Flextube Dob, 150mm Newt, 150mm Mak and an 80mm ED Frac. The latter three can be mounted on an AZ4 manual mount or an AZ-EQ5 GoTo with two of the three side by side in AZ mode or one in EQ mode. I regularly question myself about which of them I really enjoy most, and which I would I keep and which I would sell if I only had room for one. During my slow climb up the learning curve, I first owned a Skyliner 200p and after an outbreak of aperture fever I also had a 250px for several months. The latter needed some significant breathing on (cleaning up in general, washing mirrors, swapping out a dodgy focuser etc) and I fitted up both scopes with digital setting circles, Wixey's and leveling bases I believe I should have been satisfied with the 200p. With the benefit of hindsight, I think most of my observing was limited by the quality of the atmosphere, and my somewhat aging eyes, and not by the equipment. The fact that the 200p and 250px scopes have identical focal lengths should have made it easy to pick out the differences made by the aperture differential. I persuaded myself that the slightly greater 'astigmatism' or was it 'coma' at f4.7 of the 250px required better quality eyepieces than the f5.9 of the 200p. Many authors do suggest that f5 is a threshold, if not a cliff edge, beyond which higher quality eye-pieces are a requirement. Of course you might buy a good example of a particular telescope model or a rough example of the same model - and it's quite clear that we are required to carry out our own personal quality control of such inexpensive Chinese made equipment. I have two other opinions on aspects of your dilemma (200p versus 250px Flextube GoTo): Weight - My 300p Flextube is heavy - about at the limit of my capability to deal with comfortably when divided into base and OTA. I would prefer a fixed tube version except that I like to use a binoviewer for viewing the Moon and planets. This requires me to set the truss rod fittings about 10cm down from their maximum positions to achieve focus through the BV. But the GoTo Flextube scopes are that much heavier, which for me would be beyond comfortable handling on my own. GoTo accuracy - I have owned an EQ5 Pro with the SynScan v3 handset and more lately the AZ-EQ5 GoTo mount with the v4 handset. Both have tripods can be adjusted to physically level the mount before you begin alignment procedures. I have learned just how critical this leveling is to the success of subsequent alignment and GoTos. The Flextube base has no inherent capability for leveling adjustment so if you plan to make a suitable trolley or truck base for moving it, don't forget to build in some leveling screws, that preferably would reach down to terra firma. If you can persuade your friend to let you have the 200p back on long term loan you could end up being a happy man!

My childhood interest in astronomy had mostly been in suspended animation until recently when I retired and found myself occasionally in the Shropshire countryside under dark skies. My wife was surprised to discover my long hidden passion for astronomy, so I set about trying to recall my earliest memories to explain all to her. One of the stories I told her has just been wonderfully and vividly clarified. For a month or so, it has been possible to search the early copies of the BBCs Radio Times which have been put on line http://www.bbc.co.uk/blogs/aboutthebbc/posts/Genome-The-Radio-Times-Archive-is-now-live. After a few stumbling searches, I quickly found the reference to the programme that set off my early attempts at practical astronomy. I don't think I ever watched The Sky at Night in those days since I was in bed by the time it was broadcast. But I regularly watched another Patrick Moore monthly called Seeing Stars which was broadcast in Children's Hour on a Friday. I know that I always had to fight to be able to watch the programme, against opposition from two sisters who would have preferred to watch whatever was on the other channel (Tyne Tees TV ) at the time. And the most memorable programme was the one which was broadcast, according to the new website, at 17:40 on Friday 13 March 1959. I recall particularly the accompanying story with photo in the Radio Times showing a 16 year old 'Northumbrian astronomer' who was building an observatory, like a small version of Mt Palomar, to house his telescope. The programme was very good, but more exciting than usual for me because I was living in Northumberland at the time, about five miles from Shiremoor, the village where the young man, Raymon Lane, himself lived. When my dad came home from work, I showed him the photo of the young man and his observatory, and immediately after supper, we got into the Morris 1000, and drove to Shiremoor. My dad popped into a local pub, asked a couple of questions, and within minutes we were parked outside the house 'with the observatory in the back garden'. Of course it was daylight and the sky was cloudy, nevertheless we knocked on the door..... Over the next few weeks, whenever there was a moment of clear night sky, we made visits to Raymon Lane at the Shiremoor observatory, which housed a wonderful brass 12" Newtonian reflector on an EQ mount with slow motion controls and a clockwork RA motor. We had to stand on a ladder to reach the eyepiece so my guess is that the scope was about f8. I well recall seeing a crescent shaped Venus but not many other noteworthy objects though the telescope. My dad asked Ramon what sort of telescope he could suggest for my birthday, and I was thrilled to receive Raymon's second hand scope - a 4" Newtonian reflector on a simple EQ mount (no fine adjustments for latitude, or azimuth, and no slow motion controls). I think my dad paid him £12. After a few rather frustrating attempts at star gazing through this scope, I went back to looking at the sky with naked eyes alone. I remember that the secondary mirror was a prism, but the mounting arrangement was a crude metal strap which probably had to be bent to position it correctly. I don't recall any facilities for collimating the primary mirror, but then I was only nine years of age. I think the telescope spent a couple of years gathering dust in the cupboard, and if I recall correctly my dad sold it on to a neighbour (hopefully one with some optical engineering skill). Fifty five years later I've finally got my own 12" Newtonian (Dobsonian these days of course) - pity I haven't still got nine year old eyes!