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Celestron Starsense Autoalign unit – Page 2

Problem No. 1:

But not everything went to plan. Firstly, the small dovetail mount of the SSA camera was too tight at the rear to fit fully into the finder scope mount. This meant I had to sand it down in order for it to fit properly. But now that it is done, it fits much better.

Small mount foot too large to fit Finder mount - sanded down with Dremel tool
Small mount foot too large to fit Finder mount – sanded down with Dremel tool
Now the foot fits better
Now the foot fits better

Problem No. 2 (my mistake):

With everything was set up, I started to do the star alignment (by inputting the location in latitude and longitude, the date and time – I only needed to do this the first time as it seems to store it in memory). This was where I made my first mistake. I did not take off the cover from the SSA camera lens, which resulted in it not being able to align the stars (too few stars); it seems this is a customary mistake as many reviewers have mentioned this  – and after reading it, this mistake still happened to me (twice on two consecutive days). But once the cover was taken off, the alignment process went very smoothly and was a success.

Problem No. 3:

Now as the SSA camera and the telescope will not be pointing at the same spot in the sky, due to the offset of the SSA camera from the telescope, the next step would be to calibrate on the telescope to bring a chosen star right into the centre of view on the telescope (with rough and fine adjustments). Once that is done, the SSA will capture an image of the sky again and calculate the offset from the telescope and correct for this in future. The SSA will need to do a realignment afterwards.

It all sounds very easy but this is the next thing which did not go well. As I could not mount my red dot finder on the scope (due to the SSA camera having taken its place), I found it exceedingly difficult to find the star I was supposed to be slewing to. I even tried to estimate the amount of slewing I needed to do with Jupiter and the moon, but I just could not work it out.

And when I thought that I had got the right star in the centre, accepted the calibration and did a realignment, I slew to Jupiter to confirm that the calibration was right, but Jupiter was no where in view. By this time I had spent over 1 hour trying to do the calibration (whereas each alignment only took about 3 minutes). I was about to give up when I realised that there were screws located on the side of my scope which were in a straight line and could act as guides for slewing. So I centered the scope on the star Procyon using one set of screws as guide and the mounting bar on the side of my scope (at 90 degrees to the screws) for the rough adjustment of the two axis.

That did the trick and I could adjust my calibration until it was dead centre in my 5mm reticle eyepiece. What a relief! I confirmed the calibration and did a realignment and then slew to Jupiter. Lo and behold it was in the centre of my 24mm eyepiece. In fact even when I switched to my 5mm reticle eyepiece it was still in view which is pretty amazingly accurate. Do be aware that if you collimate your telescope, you will need to calibrate the offset of the camera to the telescope again – something I learned on the second day of use as I had just collimated my telescope and slewing to Procyon showed that it was off centre although still visible with my 24mm eyepiece.

Here are some images of the handset:

SSA scanning the skies and acquiring stars for alignment
SSA scanning the skies and acquiring stars for alignment – for my Equatorial mount it does it 4 times until you see the number 4 at the bottom left (currently showing 1)
It shows that it has acquired 100 stars which is the maximum. In poorer conditions (e.g. cloudy) it may pick up fewer stars.
SSA analysing the image captured against its database to determine the area of sky it is pointing at
SSA analysing the image captured against its database to determine the area of sky it is pointing at and solving the spatial orientation of the scope

As the skies cleared last night, I decided to set up my telescope again, partly to check the version of my Starsense firmware. Looks like it is definitely the latest including the polar alignment procedure.

Latest firmware - allows for polar alignment
Latest firmware – allows for polar alignment

So all in all during the first night, I managed to realign the scope at least 5 to 6 times with the SSA – and each time it did not take very long at all; this is something I would not have been able to do without the SSA. And other than the times when I had the cover on the camera (and it could see nothing), I have not had a failed alignment. In fact, it even succeeded to realign when the clouds came in – it picked up stars which I could not see, which was amazing.

Last night, I managed to recalibrate the Starsense after I recollimated my scope again, which only took a few minutes. Next I proceeded to do the All star polar alignment. At the start my polar alignment was way off but I managed to center it first with my 24mm eyepiece then with my 5mm reticle eyepiece. I did a realignment again followed by a second All star polar alignment. This time, my chosen star Procyon was actually visible in my 5mm reticle eyepiece straight away. I re-centered it again and did a realignment and voila – a perfectly polar aligned mount/telescope.

Following this, I swapped my eyepiece with my Olympus E-PL5 to test the tracking. I did 2:30 min subs using Liveview mode which allows for you to see the exposure as it builds up – great for astrophotography. I was amazed that I could get perfectly round stars without star trailing. Previously this was only possible with guiding and on a 1.6x crop camera. Now I could do the same length exposure on 2x crop camera and without guiding. You can imagine that the Starsense has breathed new life into my Celestron CGEM mount. I did further subs last night and only 1 out of the 16 2:30min subs had slight elongation of the stars.

What is good about the Celestron Starsense Autoalign?

1) It works and automates a process which can be tedious, especially if you need to do this for visual observation and then again when changing equipment for astro-imaging.

2) With the SSA, I can set up the system for imaging straight away and balance the system accordingly, as the SSA will take care of the alignment (no need to have an eyepiece in the scope to check alignment). So there is no need to swap gear unless I also wanted to do visual observation.

3) It was able to pick up stars even with clouds in the sky. So even if it is cloudy, the equipment can be setup and be prepared for when the skies clear. This is a great bonus in England where clouds do roll in every now and then.

4) You can do realignments when you need it. And extra calibration stars can be included to make the alignment even more accurate.

5) The All star polar alignment works very well, and the fact the Starsense does the realignment afterwards means this is no longer tedious and with practice can be done in just a few minutes. And it is accurate enough to be able to do 2:30min subs at 3200mm effective focal length (1600mm scope with 2x crop factor camera).

What could be improved?

1) The small mount dovetail can be fairly tight at the back end and not allow the SSA camera to fit fully in the finder scope mount – I’m not the only person to have encountered this.

2) The calibration of the camera to telescope offset was tedious and nearly made me give up. So this needs some ingenuity to find an alternative way to align the stars to the scope as I have found – so no longer a problem.


I am aware that many users have voiced their concerns about the Celestron Starsense Autoalign in the early days following its release. But it does look like there have been improvements in its functionality through firmware updates. Even its manual has been updated (previously it only had 24 pages but the current version has 28 pages). Celestron has corrected for the accuracy of pointing to the planets with its firmware update, and addressed many other issues brought up by early users, is reassuring.

Hence the Celestron Starsense Autoalign gets a big thumbs up from me (Highly recommended if you have a compatible computerise mount). The fact I can do the alignment to the stars by simply pressing a button, going inside the house to do other things (assuming I remember to take the cover off the camera – need to keep reminding myself) and come back to find that the star alignment has been done for me is fantastic. Now that I know my firmware is the latest which supports polar alignment adjustment, and the fact the Starsense has helped me get my polar alignment correct in minutes, makes astronomy a whole lot easier now (imagine the two words Polar alignment used to give me horror – no more).

Also, a big thumbs up to Tring Astronomy Centre, who updated the Starsense for me and have said they will do the update of future firmware for me for the SSA (I may not do this as it is already working so well) which is great as they have the necessary kit to do this. Talk about good service.


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