C8-N GT First Light

[russ]

Amazingly I had my first light on the day of delivery :shock: A big thanks to Steve (and DHinds) for such a quick delivery. Ordered 2pm Wednesday, arrived 9am Thursday......that's good!!!!!!!

The Mount

More or less knew what i was getting having just sold the non GOTO version. It's fair to say it's a lottery with the Chinese kit. My last CG5 was smooth and without any play in the RA axis. Sadly not the case with this sample. Very stiff and sticky in both axis, plus a bit of play in the RA. The play was enough for a star to move across the entire field in a 25mm 52AFOV eyepiece. It also means the damp down times are quite lengthy. And the scope gets the jiggles.

Also need to sort out the backlash on both drives......the backlash is massive. Never quite seen it this bad on a mount straight out the box. Needless to say the GOTO was way off, struggling to put things in the field of the 9x50 finderscope.

The drives are noisy but not Meade LXD75 noisy. I didn't feel a need to hide! Although they were noisy enough that I didn't feel comfortable using them after 11.30pm.

I used the mount undriven for the most part but this was very frustrating due to the sticky nature of the movement in both axis. It was hard to just nudge an object into view. The mount would stick, then release and then go too far.

So at the moment it wouldn't be fair to comment on the mount. I think it needs a full strip down to it's component parts. Rebuilt with a cleanout, regrease and play with the gears. So a visit to Astronomy Boy will be in order.

The Scope

No surprises here. This is my fourth Synta 200mm f5 Newtonian and it's as good as all the others I've owned. Collimation was a tad off but too be expected after just been manhandled by the delivery boys.

I went out too late for Jupiter but the Moon was sharp and detailed. M13 was simply beautiful, resolved to the core. M81/M82 were nice considering the moonlit night sky.

I was hoping to do a GOTO tour but with the GOTO so far off that will have to wait.

The focuser was no surprise. Sticky and with plenty of image shift. I know this can be rectified to an extent but I can't be bothered. Going to replace it with Synta's own Crayford as used on the ED's. Also going to add Synta's electric focus at some point.

Overall impressions

No real surprises really. Synta kit is a lottery. I got lucky on the last CG5 but not so on this one. It will definitely need a rebuild and a fair bit of work. My HEQ5 and LXD75 required some (LXD75 required lots) work too. So it's just a Chinese thing.

The 8" f5 was as good as I hoped. And once the focuser is replaced it will be perfect.

Regards

Russ

[centroid]

A very good and honest review Rus!

Sorry to hear about the problems with mount, but with a bit of work they can be 'sorted', albeit you really shouldn't have to be doing that with a new piece of 'kit'.

My first scope was a (Celestron G8 SCT), with an EQ5 mount, and this was 'put together' with a thick black treacle like grease, which did nothing for the smooth operation of the mount.

I then found a very detailed article on stripping down, cleaning, and re-greasing the mount. The result was a very significant improvement.

Good luck, and hope you get it sorted, to your satisfaction.

Dave

[russ]

Thanks Dave.

I did think about returning the mount but to be honest I have had EQ5/CG5 which were far worse. My worry being this isn't horrendous but the next one could be. And it could be weeks before i'm up and running again.

I'm gonna sort out the backlash and RA play over the weekend, then decide on the sticking/stiffness later. It will be just the job but just needs some tinkering to be right. A work in progress at the moment.

Russ

[centroid]

Its always the risk when getting a sub-standard item replaced, that the replacement may actually be worse.

It its something that you can put right yourself, then its often better to 'stick' with the one you have.

The only downside being that you spend good money a new piece of 'kit', only to find that its poorly built.

Dave

[Whippy]

Good review Rus, firm but fair as they would say. Sounds like I got lucky and you didn't. If in the unlikely event you need anything, let me know mate.

Tony..

[russ]

What is annoying, I sold the other CG5 (5 weeks old) to a chap at work. He'll never use it, it'll never see the light of day or the dark of night :? I wish i hadn't handed it over so quickly, just needed a day crossover period. Could have swapped things around. He now has a spot on CG5 which won't be used (like the last thing I sold him) and I have a not so spot on CG5 which will be used a lot. Poo! :insects1:

Russ

[Whippy]

Surely go round his house and swap it round without him noticing!! Bit of effort but if you get him drunk before hand, all you need to do would be the mount head..... :shock:

Tony..

[Black Shuck]

Russ,

I enjoyed reading your review, but it is a shame that the CG5 is poor. I am lucky (like Tony) in that I got a good one. I agree that I would be very tempted to sort it out myself but I am sure it will invalidate your warranty.

I would be inclined to drop a line to Steve/D Hinds to let them know and give them chance to offer a solution. I am sure that they would be mortified that you are having problems and would everything they could to sort it.

Hope you get sorted soon

Bill£

[russ]

It's really not that bad to be honest. Just to iron out the play and backlash would be fine. I think i'm making this sound far worse than it is. Fussy astronomer is all.

Pretty sure Steve/Adam would wonder what i'm talking about if they checked it. :shock:

Besides I can't go a week without a scope with clear nights forecast

Russ

[FLO]

It's really not that bad to be honest. Just to iron out the play and backlash would be fine. I think i'm making this sound far worse than it is. Fussy astronomer is all.

Pretty sure Steve/Adam would wonder what i'm talking about if they checked it. :shock:

Probably, but I'll be guided by you Russ.

I know you know the difference between a faulty mount and one that is within spec but can be 'improved'.

If you'd like it changed, give me a call

[russ]

I'll play with the backlash settings this weekend, see if can sort that out. And perhaps adjust the play in the RA.

Hopefully the mount will loosen up with use and solve that problem itself.

You can have look in two weeks time

Regards

Russ

[MartinB]

The polaris mounts are very similar and I have spent a lot of time tweaking the back lash and taking out play on my SP and GPDX. The slop should be easily reduced by taking the nut off the worm and tightening the threaded wotnot until the play is gone. with the GPDX I can remove all play but with the SP I have to leave a tiny amount or the gear starts binding.

The backlash adjustment is very fine getting the set screw loosened to just the point where the play in the gears virtually disappears, a gnats whisker further and it sticks.

[Rob]

Blimey.. I go on holiday for a week and his bought a whole new setup!!!...... ok, so you have a few glitches to sort. But it sounds the business all the same Russ. Nice one!

I'm guess the setup is coming with you to Salisbury in a few weeks?.

Rob

[GordonCopestake]

The CG5 is a great mount for the price. I think at the end of the day the reason mount prices go up is NOT due to load capacity but due to the amount of time you DONT have to spend getting it to work. The most expensive mounts just work out the box, but you have to pay a lot for that. Even the losmandy stuff you have to play with to get it right. I've never heard of anyone stripping and re-greasing an AP1200 though

[russ]

I used it again last night to see if i could sort the backlash but gave up. There's too much play in both the RA and DEC. But the DEC seems to have a few other problems. As the DEC turns, it reaches a certain point and then judders/jolts. Almost like there's a broken bearing or something.....not sure. It's also quite stiff. There's heaps of backlash on the dec, which was last nights job but seeing the play and the jolt, I decided it was best to quit.

I'll give you a call Monday Steve.

[Rob]

Humm... this sounds like a lemon to me Russ. I think a replacement is in order TBH. You have paid good money for the goods, they should be right!.

I'm sure Steve will sort this out for you, no problem.

Rob

[FLO]

No worries Russ, I'll arrange that is collected Tue and a replacement sent out :salute:

[russ]

Hold on Steve. Sat down with the mount this evening and just checked things over. A lot of my problems seem to come from the DEC motor cover. On closer inspection the jolt was caused by the DEC cover clipping the DEC axis clamp.

Problem number two, the dovetail wouldn't sit flat in the saddle and the scope ended up rocking (which in the dark felt like play in the DEC axis). In the light of day this turned out to be fault of the DEC motor housing again. Put on crooked and one side was sitting proud of the saddle. This meant the dovetail couldn't sit flat.

Problem number three, the DEC axis very stiff. Well this was caused by the DEC axis clamp. It's very loose and just falls back down and re-clamps itself enough to stiffen up the movement.

Played with the backlash settings and those are far better now. Also did a 2 star alignment plus calibration star. The GOTO nailed 9 objects from each part of the sky. Putting them in the field of a 10mm Plossl.

Steve, the mount is performing okay....I'm happy I'll give you a call Monday to discuss the DEC motor housing.

That's all the good news, now the bad. I had to stop slewing around at 11.40, as a neighbour a couple of doors down told me to " shut that f@#*ing up". So in answer to questions regarding the noise......it's bleddy noisy!!!!

Should be better once winter comes round though. I can get some good observing time in before turning off the drives at 11pm.

Russ

[FLO]

Steve, the mount is performing okay....I'm happy

Well done that Man

Will sort the DEC motor housing ASAP :salute:

Not good news about the neighbour!!!

[Whippy]

That's all the good news, now the bad. I had to stop slewing around at 11.40, as a neighbour a couple of doors down told me to " shut that f@#*ing up". So in answer to questions regarding the noise......it's bleddy noisy!!!!

Should be better once winter comes round though. I can get some good observing time in before turning off the drives at 11pm.

Russ

Charming!! At least you know what to do when they have some friends round for a barbecue..........

Tony..

[russ]

Hard to say anything at the time but yes I will wait for my moment. Probably when his fisherwoman wife is going off on one and the whole street can hear them. I will take great pleasure in telling them to "shut the beep up"

I did try walking away from the mount to see if it was as loud it sounds close up. Even from the front of the house with the house in the way, I could still hear struggling on its journey to M57 from M31.

Funny all slews upto max are deadly quiet, just that final number 9 slew. I really wish Celestron would implement the quiet mode like Meade. I don't mind waiting a little longer.

Steve, chat tomorrow

Russ

[christo]

Hi people,

This is slightly off thread, hope you don't mind. I've a C8-NGT set up that I've owned for around 18 months and was wondering about the alignment process. Rus you mentioned that you completed a two star align but I don't have that option on my set. Think I saw somewhere that a newer version since mine has been made available which might be what you have. If this is the case can I upgrade to the newer system? Is it worth doing so? and...does the new system have any other benefits?

Cheers folks,

Chris