Cosmic Geoff

Seeing the rooftop inverted strongly implies that you are not using the star diagonal. You should use it to avoid pointless neck-ache when observing the night sky.  Fitting the diagonal will give you an erect image (but reversed L-R) and require a significant refocusing.

37 minutes ago, Anuradha said:

.however still I see like a black circle sort of dot  in middle of the image is that how it actually appears ?

We have seen a number of newbies complain of this, particularly when using a low-power eyepiece. Needless to say, I have never had this problem with my telescopes, and avoiding it is probably a matter of getting used to using a telescope.

You should not need a 40mm eyepiece for that purpose.  With the Nexstars (including the Celestron equivalent of your scope) I have found that the Goto alignment if properly done will place objects within the field of a 25mm eyepiece.  If you are not getting that degree of accuracy with your Az GTi, some attention to the mount or alignment procedure may be required.

BTW you might as well have a 32mm 1.25" Plossl, as the actual FOV will be the same as with a 40mm 1.25" Plossl.

It should not be dificult to get the 8 SE into focus if pointed at a suitable target. "White" suggests you are trying this in daylight. You need to find a high-contrast target such as distant tree branches against the sky, and then wind the focuser till it comes into focus. 

If you focus on a distant point of light at night and the focus is not too far out, you will see a bright disc or donut, which makes things much easier as you wind the focus knob in the direction which makes the disc smaller.

If finding objects quickly is part of your requirements, I suggest a C6 SE or C8 SE GoTo SCT.  The C8 has the aperture to show lots of galaxies and other DSOs from a dark site, and is compact enough to be easily transported by car and light enough to be carried a modest distance.  Not cheap though, at today's prices, unless you can pick up a used one.  I have taken mine down to rural Devon a couple of times.

2 hours ago, Trevor Matthews said:

If anyone wants to sell a 6.3 focal reducer suitable for my 8SE I would be interested......

When I looked for one a few weeks ago I saw several on ebay and eventually got one via astrobuysell.com/uk/

In my experience with the same mount, a bad power cable connection will definitely cause malfunctions.  You can splay the split centre pin slightly with a craft knife, and attach a cable tie to stop the cable shifting around at the inlet.

You can also get a bad connection where the handset plugs into the mount arm.

If the handset cannot get a response from the mount, an Error 16 or Error 17 will result.  The cause can be scrambled firmware (had that), or a failed internal connection ( not had that) or a general failure caused by something like water in the connectors (had that).

It is not a simple matter to refresh the firmware even if you have a working mount and handset and power. See nexstarsite.com for guidance. How far do you get before encountering an issue?

Any error codes?

Have you checked that the power cable is making proper contact, and/or the battery is charged?

Has any water got into it?

59 minutes ago, bf79 said:

and when I try to do a firmware update on my laptop it doesn't find the mount. 

Did it find the mount previously? Various things have to work for the firmware update to succeed.

I imagine Celestron can supply a replacement board as a last resort, as this is a current model.

Before you buy anything else, buy the book "Making Every Photon Count" by Steve Richards.  This book is an essential introduction to astrophotography and should answer many of your questions.  It is available from forum sponsor FLO.

A competent electronic engineer would be able to de-solder the power jack and replace it with an identical part. (A solder-sucker or other tool will be required).  Tomatobro however is suggesting that there is a break in the PCB tracking. A competent engineer would also be able to fix that by some suitable means, eg by repairing the track or bridging it end to end with a piece of wire joining the solder pads.  This could also be an opportunity to replace the not-very-satisfactory  original jack by a better designed part.

Whether you or your kids feel competent to do this is up to you - otherwise seek professional help.

It would be inadvisable to try moving the outfit fully assembled. If you store it as separated OTA and mount/tripod, and separate counterweight, two or three black binbags should suffice to keep dust and drips off, as well as screening the kit from prying eyes..

Further to my previous post, I dispensed with the flip mirror assembly, using a star diagonal to give some spacing.  It is fairly easy to manage without it. The widened field of view also helps... Using Celestron's 'Precise Goto' the 'PG' aligning star sometimes appears in the camera field, and if it doesn't, the 9x50 RACI finder can be used to correct the aim. 

I also found out that it was possible to do a plate-solve on a rich starfield with this setup, with Sharpcap/ASPS

NGC2440 was quite low, so low that the 'precise Goto' star was behind a building and I had to manage without.

A lot of the cheaper zoom eyepieces of sundry brands are essentially the same (you can tell by looking at the specs and sales pictures.)  Some models of the 7-21mm variety were reported to be awful.

I have a 8-24mm BST Starguider zoom which looks just like several other brands, e.g. Celestron. It did not cost much, and performs quite well optically.  BUT the action is so stiff that I have to take it off the telescope to adjust it, and the FOV at 24mm is so small that I never use that setting.

A small FOV at lower power is a common feature of zoom eyepieces.

I tried this a few times using simlar techniques to planetary imaging. It works well with doubles of roughly equal brightness, less so when the brightnesses of the components are very unequal.

On 15/02/2022 at 19:15, Mike JW said:

I found/find that if I align accurately and two star sync, then sync to a known star or DSO in the region of interest then the DSOs I am planning to hunt down are always in the fov.

Good suggestion. I intend to try doing without the flip mirror at the next observing opportunity. 

That might be a long search.  New and used 4 inch to 6 inch telescope tube assemblies are now so cheap in the West (compared with average wages) that there is no interest in new pre-made mirrors of these sizes.

There is a site https://www.astroboot.eu/AstroBoot which sells parts removed from unsaleable telescopes, which might have what you want sooner or later. (They have some 76mm dia mirrors in stock).   I do not know if they ship to India - currently they do not ship to the UK because of Brexit, which is not encouraging.

I have acquired a f6.3 focal reducer and tried it out last night. First results indicate that it is a very worthwhile purchase. Images of the same PN with three different setups are shown below. 

Unfortunately the extra length of the reducer causes the imaging train to hit the forks base at altitudes above 70 degs - a major problem. I will have to figure out a workaround - can I find objects without the flip mirror diagonal while maintaining the backfocus in the recommended range, or find a more compact adaptor to connect the flip mirror and reducer (that would be T2 to SCT thread)?  

17 minutes ago, Marc1964 said:

Any particular RDF that's reasonably well built?

The Baader Skysurfer III. I have tried others and this is well made and the most reliable so far.

I use a Baader Skysurfer III on my 102mm f5 Startravel (same focal length as your scope).

I used the basic red dot fnder with my ST102 Startravel, but when it failed (as they do 😧) I bought a Baader Skysurfer IV.  I never saw the need for an optical finder.

Why not buy the ZWO IR-cut filter, which costs about £20?  It's purpose is to block the IR (to which the camera is quite sensitive) to prevent colours looking off.  If you try the camera in daylignt with the fisheye lens supplied you will soon see what I mean...

6 hours ago, huddo said:

ollowing a visit over to the North Norfolk Astronomy site I’ve been advised against a Schmidt Cassegrain on the grounds that they’re not the easiest of telescopes for beginner to find targets.

I don't think this is sound advice.  With my 127mm Mak - a similar aperture to your proposed purchase, but with a focal ratio of around f12.5, I don't have trouble getting things in field even using it manually on an Az-4 mount (it came with a SLT GoTo mount).  The SCT is f10.

There are various choices open to you, each with their own peculiarities, pros and cons. 

39 minutes ago, BackyardAstro said:

Stellarvue m2

Just my opinion, but I do not think a manual alt-azimuth mount is a good match for a scope with a 2 metre focal length, even with the addition of a Starsense.

The general opinion seems to be that Celestron and Meade SCTs are both good (meaning the OTA) but the Meade mounts do not have a good reputation for reliability.  Meade also had some kind of financial problem recently which you should look into before buying.  You should also look into what sort of reputation they have/had for technical support as I don't want to type anything prejudicial without checking.

You should also note that large SCT outfits are often a whole lot cheaper on the second-hand market.  Like half the price of a new outfit.  For instance, a forum member is selling a C9.25 OTA for what looks like a give-away price.

" I will liberate a starsense explorer mount for the upcoming SCT."  The SCT probably deserves a better mount than that. If it's for visual, you could buy the Nexstar Evolution C8 bundle.

It is questionable whether you need the ACF or Edge options unless you are going to image deep-sky objects with your SCT, in which case you need a serious equatorial GoTo mount.
 

The CPC/heavy duty tripod is a lot heavier but very rigid. Celestron supply it with a 11" SCT.

The C8 SE tripod+ mount is not bad so long as you use it for visual in a sheltered location with the legs retracted to minimum length.  The tripod itself is vey light.  On the plus side, you can leave the whole outfit assembled for storage and carry it through a domestic doorway.  For transportation, the mount/OTA comes off the tripod easily but if you split the OTA and mount (by slackening one clamp knob) you have the problem of holding a fat OTA that has no grab handle and needs two hands to hold it securely...   

The main reason for choosing the Evo 8 over the C8 SE is that the Evo has a better quality mount. The tripod is different but may not be much stiffer than that of the C8 SE (it looks much the same in photos).   It has WiFi, and yes there is a battery, but it's rather small and uses the kind of chemistry found in laptop batteries.  Some Celestrons have the heavy duty tripod ( distinguished by a large cast aluminium eyepiece tray and separate spreader) which is far more substantial (and quite heavy).

46 minutes ago, DavieH said:

This is likely to be my last scope.

Dangerous words...