EQ8 and long FL scopes

[nmoushon]

I'm still trying to decide on a mount that would handle a scope of at least 2000mm+. My eye is currently on the C11 Edge, so closer to 3000mm. I originally had my mind kind of made up for an AP900 but at a $6-7k price point it is a hard pill to swallow on my kind of budget. I keep going back to EQ8 as its spec say it should easily be able to handle these kind of scopes and the price is almost half of even a used AP900. Now I know the AP900 is a better overall mount. I'm not looking to compare the two or even compare it to other mounts as I know there plent out there that would do a better job. Not saying the EQ8 is a bad mount just that its not up to par with some other mounts that are typically use for long FL imaging.

So I'm looking to see how many people are using their EQ8s for long FL imaging and what are their thoughts and results so far. I know theres been some bad apples that got shipped out, i.e. the one Olly got and had to return. So for those that kept theirs did they have to do any major/minor tweaking to get theirs to work properly? I'm not opposed to do some minor tweaking to get the performance better but I also dont want to have to strip the whole mount appart to get it to work the way it is advertised to, new mounts shouldnt have to do that. What kind of of FL are you working with? What are your typical sub lengths you can consistantly get and whats your max? Are you having to throw away a good chunk of your subs or just a couple here and there?

I'm trying to get several honest reviews of how its been working for people.

Thanks for any comments.

PS: I have read every thread on here and cloudynights about them.

[libraryman]

I currently image with an eq8, however my imaging is relatively short f/l. Reading a good # of posts regarding long f/l imaging, it seems to me that it's potentially difficult irrespective of your quality of an eq mount!

The eq8 is a discount mount in that it does the job but its not a premium build! You get what you pay for!

However that said, most if not all current owners appear to be happy with it, the things that really matter are its ability to carry weight and perform reasonably well when guiding, your local seeing conditions will effect that aspect.

The mount is heavy and on the limits of portability, the bearings and general build quality appear to be a good improvement over the other skywatcher products but it does not compare to AP mounts unless you factor in price and accept its relative weakness's such as paint, appearence, rough castings, and a slightly higher periodic error, though I have heard claims of less than 4 arc seconds PE.

Mine has a small but perceptible backlash in Dec that I cannot reduce, born out of a slight eccentricity in the worm wheel.

Any worm wheel arrangement has the potential for backlash, its this that will make guiding at 3000mm difficult.

I may be at odds with popular opinion but I would suggest a different arrangement for that focal length I.e a mensu.

Ray

[nmoushon]

Thanks for the input Ray. I have seen a lot of people post great images taken with the EQ8 at short/er FL. Several have done tandem imaging setup, triple setup even, and have done some spectactular images with it. If I was going that route I would be leanning more heavyily to the EQ8. But I am looking at long FL for imaging so I do know that who different cup of tea.

I do realise that local seeing will effect a lot of things and no mount can correct for that. ItS some smaller errorS that cause bigger problems, like the eccentric worm wheels, that has me on the fences edge still.

This mount would be on a pier in an obsy so portability is not an issue for me.

I know I have to weigh it for its price. Im not trying to compare it to the AP900 or Mesu. Im trying to get some reviews to try to compare it to its price point.

[libraryman]

If its the possibility of eccentricity in the worm wheel that worries you, then i would tentatively suggest that you put that out of your mind, despite a lot of bad press; i hold the view that any worm & wheel will have a degree of eccentricity in it..it's a matter of how much!!!

You would be hard pressed to find any physical evidence of back lash on my mount; using the oft suggested method of rocking the saddle plate!!   The eccentricity i speak of only manifests itself in a slight delay moving South in calibration & that delay can be magnified by the fact that i use a guide rate of 0.30x or less..sometimes 0.10x.

Its small but, i would never say its not there, the truth is that eccentricity can be just a tenth of a mm in the depth of cut one side of the wheel to the other that will give a tightness on the worm, ( my case)  its most unlikely the the worm itself will be eccentric or not running true in my humble opinion.

I think this is the difficulty with worm and wheel arrangement, unless you pay for Paramount and AP construction!!... and even then, the machining may not be perfect until its bedded in or blue printed.

when I'm guiding, i have my aggressiveness set well below 50% and my guide rate very low, this adds up to a mount that will guide well and is far more indicative of a good mount than just the evidence of a little backlash.

we agree that with your ask of good guiding at 3000mm, the seeing will likely as not play a greater role in your guiding accuracy, though i guess you can mitigate it with a good guide scope to imaging ratio and a good clean image from the guide camera.

Hopefully you get the opinions of people better placed and with more knowledge than i to provide an opinion.

Regards Ray

[Jussi_K]

I have Eq8 and GSO RC 12". Focal length is about 1710mm with reducer. I can take one hour exposers with  (tested several nights in a row) SX costar on the OAG. Encoders went nuts and almost broke my camera last winter, I disabled them by taking encoder wires of the motherboard. Im quite happy with the mount, if I don't count the encoder problem.

[tony210]

I have to agree with Ray - I image at present at 1.2 m FL and I think the mount is very good for me but it  does have Dec backlash that cannot be tuned out - great payload allowance but at 3m FL I wonder?- It is after all a great effort I feel, by Sky Watcher, at an attractive price but with understandable limitations - I still think it will be adopted by many at this price and serve well for visual users and some astrophotographers who always grapple with limitations in the equipment's aperture, focal length dilemma -Tony.

[ollypenrice]

I would have thought that, at a three metre FL, backlash perceptible to touch would be enough to spoil the data.

So is it now accepted that there is a consistent problem with Dec backlash on the EQ8? I haven't seen much news recently. The amount mine had was too much for even a quite short FL. Perhaps there will be a fix from SW by the time you're ready to buy.

Olly

[FLO]

So is it now accepted that there is a consistent problem with Dec backlash on the EQ8? I haven't seen much news recently. 

Olly

That is only your wishful thinking Olly

Your campaign against the EQ8 has not dented it's success but it has driven much of the discussion off the forum (imagine your response if someone bad-mouthed your Mesu every time you mentioned it). The EQ8 is alive and well having been installed in observatories up and down the country, including a number in astro societies, schools and universities. 

But I'll share this with you: By focusing on backlash you missed the mark because all mounts with worm-and-wheel drive have backlash (a little backlash is necessary for the design to work). The EQ8 doesn't have a problem with backlash but it does depend on a reliable power supply. To be fair all modern mounts need a good power supply but the EQ8 does protest loudly if you try to run it off anything less. 

Your EQ8 arrived faulty so we collected it free of charge and arranged a full refund, but faulty EQ8s are not the norm. 

HTH, 

Steve 

[ollypenrice]

Easy, Steve, I don't have a campaign against the EQ8 and I certainly never wish for other people to have trouble with their kit. It's just that in this short thread two owners discuss their Dec backlash. I simply aksed a question and if you're selling this mount and not seeing the problem then that's great. Of course some backlash is unavoidable in a worm and wheel but the question is, how much? I believe that if you can feel it with your fingers it will be too much for three metres FL, which was the OP's area of interest.

In a recent thread I pointed out that I personally know owners of every single premium make of mount I can think of  who have had significant problems at the level of return or spares sent out for a fix. This includes Mesu SiTech, Paramount, Astro Physics,10 Micron and ASA. I can only repeat that I have no campaign against any of these makes but the fact remains that they can all misbehave. I also posted today in support of the AZ EQ6 in John's thread in which your service was, as ever, of the absolute best.

Olly

PS, I also posted very openly about our recent Avalon, where I side with those who are concerned, at least, by the elasticity in the drive.  I described this at some length and gave my honest opinion of it. I posted equally openly about the primary drive backlash which affects our Takahashi EM200 mount. I think I'm pretty fair, on the whole, and don't hide the shortcomings of kit I might one day want to sell. In a nutshell it is impossible to buy a mount from anybody and be sure it will work perfectly. OK, 'perfectly' is never going to happen but I think most manufacturers 'could do better,' as we teachers like to say...

[FLO]

Easy, Steve, I don't have a campaign against the EQ8 ...

So do you think you could go one whole month without posting anything negative about the EQ8?  

Seriously, you have a right to post your thoughts and I haven't criticised your advice in this thread but your negativity towards the EQ8 and your attempts to find faulty ones are well known. 

Steve

[Earl]

I did consider the EQ8 seriously, even had the pier adapter sorted as one came up sh on ABS, then an AP900 was offered to me which cost me more but is a tried and tested mount from a owner with experiance.

Id of liked to of tried an EQ8 as it ticks alot of boxes.

Of course I still look at where next, its one of the drawback this hobby has, thee is no end of upgrad potentials, but i must get one season under my belt without gear change.... (now if I can stick to that......)

[FLO]

I think the unspoken truth, Earl, is we buy what we 'want'. Not what we need. In this I am as guilty as the next person  

Steve

[nmoushon]

Thanks for everyones input. I am very well aware that this mount, and most mounts for that matter, have backlash. The existence of backlash isnt the problem Im worried with its the amount of backlash. I've heard stories from both ends of the spectrum in regards to this. Very bad backlash and very good backlash. I'm just trying to find out what end is more weighted. I am specifically more interested in those that have tried to image with long FL over short FL bc even the smallest of errors are greatly compounded...especially if I get a C11Edge at 2800mm. Now I would love to be able to do 30min subs at that length but maybe I'm asking to much. Maybe Im going to have to drop to a 9.25 to get that length or jump up to a better mount. Going to have to weigh all my possible options.

[ollypenrice]

So do you think you could go one whole month without posting anything negative about the EQ8?

Seriously, you have a right to post your thoughts and I haven't criticised your advice in this thread but your negativity towards the EQ8 and your attempts to find faulty ones are well known. 

Steve

I can answer your first question authoritatively by looking back through my EQ8-related posts and the answer is 'yes.'

I'm done on this thread and am sorry that I provoked a spat in this way. Apologies to nmoushon. Good luck with your search. Imaging at 3 metres is never going to be easy but one thing that might be a help would be an active optics unit. I'm told they are a pain to set up but they can really do wonders at these FLs. I've seen a couple in action here.

lly

[libraryman]

I think that the comment "consistent problem with Dec backlash" is a misleading term! that implies..every EQ8 is faulty!!

 

This is a perception that has to be ignored!

It also implies that the dec backlash is a real problem for all users of the mount..it is not!    Moreover; it is appears as an attempt to undermine the equipment that people have spent good money on, though i'm quite sure it's unintentional.

I find mine just fine, i think as Steve say's other owners do too.

 

Ray

Ps, whenever i speak to people who have been to Olly's, they are unequivocal about the praise they give to him and the opinions / help he gives, however, with respect to the perceived eq8 issues, it can be misleading.

[FLO]

Thanks for everyones input. I am very well aware that this mount, and most mounts for that matter, have backlash. The existence of backlash isnt the problem Im worried with its the amount of backlash. I've heard stories from both ends of the spectrum in regards to this. Very bad backlash and very good backlash. I'm just trying to find out what end is more weighted. I am specifically more interested in those that have tried to image with long FL over short FL bc even the smallest of errors are greatly compounded...especially if I get a C11Edge at 2800mm. Now I would love to be able to do 30min subs at that length but maybe I'm asking to much. Maybe Im going to have to drop to a 9.25 to get that length or jump up to a better mount. Going to have to weigh all my possible options.

For most people with regular imaging setups the EQ8 offers the highest performance-per-£ so wins, particularly when considering a mount for heavy loads, but if price isn't an issue and you are looking for the 'best' performance at long focal lengths it isn't the right mount for you. 2800mm is extreme so you need a mount with very little, or zero, backlash. Olly is right (hope he's still talking to me!) in your circumstances the Mesu will outperform the EQ8. Olly is the best person to speak with for Mesu advice, being thier no.1 fan. 

I'm done on this thread and am sorry that I provoked a spat in this way. 

Don't be like that Olly, this isn't the first time we've danced together and we agree on most things 

Steve 

[ChrisLX200]

I suppose what you will look for as a prospective buyer are examples of images taken at 3M focal length - by compentant astroimagers using excellent OTAs (no point in compromising elsewhere, it is the performance of the mount that is being put under the spotlight). So where are they? If you can't find any that you would aspire to then move on. I will be upgrading my mount next year because I need better load carrying capacity and stability, my old G11 is pretty good in the accuracy department (it guides well within 1 arc-sec unless there is a slight breeze - in which case it is pants!). So where do I go from here? EQ8 has the load carrying capacity I'm looking for but doubts about tracking will very likely steer me away from it. Where is the evidence to convince me otherwise? How does one find out?

In the end I probably won't risk disappointment and go with a (much) more expensive mount like the 10Micron HGM2000.

ChrisH

[Zakalwe]

I suppose what you will look for as a prospective buyer are examples of images taken at 3M focal length - by compentant astroimagers using excellent OTAs (no point in compromising elsewhere, it is the performance of the mount that is being put under the spotlight). So where are they? If you can't find any that you would aspire to then move on.

There are some excellent examples of long focal length images on Astrobin:

http://www.astrobin.com/users/AstroGG/

http://www.astrobin.com/users/Dutchastrocolors/

http://www.astrobin.com/users/Pellervo_Observatory/

[nmoushon]

Everyone comments have been much appreciated. I specifically asked for personal experiences to look for the good the bad and the ugly. (Sorry for the pun but could not pass it up  ) Olly's experience was pretty ugly where as Ray's has been very good. I knew I would get both, I just wanted to see if the problem was as prevalent as it seemed when they were first released.

I wish I could afoord the Mesu as it really has shown itself on here as a great mount. Besides the price it is also very very hard to obtain here state side and shipping from Europe makes it really to expensive at that point. Same goes with the 10Micron unfortunatelys, easier to obtain here in the states but still out of my price range. Over twice my mount budget when looking at the GM2000 compared to a used AP900 (the GM1000 capasity is not up to snuff to carry a fully loaded C11Edge). Both are incredibly nice mounts and definately on my dream list but im still in reality right now lol.

Looks like I will have to keep saving, and maybe start selling some things, and aim for a mount in the AP900 category. Maybe by the time I can actually purchace a new mount the price will drop a bit too; who knows.

 

[ollypenrice]

OK, I'm back because I don't like spats. But, dammit, I have made no mention whatever of the Mesu on this thread (other than to say that I know people who have had trouble with the SiTech version.) I have not advocated it in any way whatever.  What on earth do I have to do to be considered impartial? Please, don't impose on me your own views of what I've said. Just read what I've really said. I'll take the liberty of quoting myself, in the best journalistic tradition of cutting out one part of the sentence, and say, 'I wouldn't touch an ASA with a ten foot pole.' I wouldn't, but that's me, and I haven't said that about the EQ8 because it isn't true, for one thing. I would still consider it.

Zakalwe's post is informative and encouraging and, yes, I did say that.

Libraryman, I did not say, 'There is a consistent problem with Dec backlash on the EQ8.'  I asked this question; So is it now accepted that there is a consistent problem with Dec backlash on the EQ8?  Why did I ask that question? Because you yourself said, 'Mine has a small but perceptible backlash in Dec that I cannot reduce, born out of a slight eccentricity in the worm wheel.' Please, you said it!! Now the OP (remember him?) was asking about imaging at three metres, not imaging, as you say you do, with a heavy payload. Like you I image with a heavy payload but short focal length, but this is not what the OP was asking about. I think (in fact I know darned well) that small backlash is bad news at long FL.

What is my crime here?  This was a post about three metre DS imaging. I've never done that. I've only imaged at 2.4 metres. Do I think a bit of backlash matters at three metres? yes I do. Sorry, but I just do. 

Now I'm really uncomfortable about this thread and will try to keep out of it. This is a non-confrontational forum and the better for it. Besides, I have to go and help align a new mount, seriously premium, not mne, and it does have a bit of backlash...  

Olly

[Sp@ce_d]

There are some excellent examples of long focal length images on Astrobin:

http://www.astrobin.com/users/AstroGG/

http://www.astrobin.com/users/Dutchastrocolors/

http://www.astrobin.com/users/Pellervo_Observatory/

Those are pretty impressive!

Everyone comments have been much appreciated. I specifically asked for personal experiences to look for the good the bad and the ugly. (Sorry for the pun but could not pass it up  ) Olly's experience was pretty ugly where as Ray's has been very good. I knew I would get both, I just wanted to see if the problem was as prevalent as it seemed when they were first released.

I wish I could afoord the Mesu as it really has shown itself on here as a great mount. Besides the price it is also very very hard to obtain here state side and shipping from Europe makes it really to expensive at that point. Same goes with the 10Micron unfortunatelys, easier to obtain here in the states but still out of my price range. Over twice my mount budget when looking at the GM2000 compared to a used AP900 (the GM1000 capasity is not up to snuff to carry a fully loaded C11Edge). Both are incredibly nice mounts and definately on my dream list but im still in reality right now lol.

Looks like I will have to keep saving, and maybe start selling some things, and aim for a mount in the AP900 category. Maybe by the time I can actually purchace a new mount the price will drop a bit too; who knows.

Well this is my take on it...

If you want the load capacity then the EQ8 followed by the Mesu at almost double the cost, really are the starting points.. full stop. Either you wait & save.... hoping it doesn't become a moving target. Sell some organs and go for that 10 grand plus ( Scottish punds of course dream mount, or bite the bullet & go for what you can afford now. You may have to compromise & adapt, tweak this and that but you'll be getting something, churning out subs and learning from it along the way.

I think the unspoken truth, Earl, is we buy what we 'want'. Not what we need. In this I am as guilty as the next person

Steve

You are right of course Steve... however I think the restriction there is the inevitable reduction in life expectancy once she finds out..

[libraryman]

OK, I'm back because I don't like spats. But, dammit, I have made no mention whatever of the Mesu on this thread (other than to say that I know people who have had trouble with the SiTech version.) I have not advocated it in any way whatever.  What on earth do I have to do to be considered impartial? Please, don't impose on me your own views of what I've said. Just read what I've really said. I'll take the liberty of quoting myself, in the best journalistic tradition of cutting out one part of the sentence, and say, 'I wouldn't touch an ASA with a ten foot pole.' I wouldn't, but that's me, and I haven't said that about the EQ8 because it isn't true, for one thing. I would still consider it.

Zakalwe's post is informative and encouraging and, yes, I did say that.

Libraryman, I did not say, 'There is a consistent problem with Dec backlash on the EQ8.'  I asked this question; So is it now accepted that there is a consistent problem with Dec backlash on the EQ8?  Why did I ask that question? Because you yourself said, 'Mine has a small but perceptible backlash in Dec that I cannot reduce, born out of a slight eccentricity in the worm wheel.' Please, you said it!! Now the OP (remember him?) was asking about imaging at three metres, not imaging, as you say you do, with a heavy payload. Like you I image with a heavy payload but short focal length, but this is not what the OP was asking about. I think (in fact I know darned well) that small backlash is bad news at long FL.

What is my crime here?  This was a post about three metre DS imaging. I've never done that. I've only imaged at 2.4 metres. Do I think a bit of backlash matters at three metres? yes I do. Sorry, but I just do. 

Now I'm really uncomfortable about this thread and will try to keep out of it. This is a non-confrontational forum and the better for it. Besides, I have to go and help align a new mount, seriously premium, not mne, and it does have a bit of backlash...  

Olly

I'm not interested in incurring argumentative debates on line, please accept my apologies Olly if i have misrepresented your intention to be neutral and unbiased.

Ray 

[ollypenrice]

I'm not interested in incurring argumentative debates on line, please accept my apologies Olly if i have misrepresented your intention to be neutral and unbiased.

Ray 

Thanks Ray, and please accept mine for exactly the same reasons. Like you, I intensely dislike such arguments and I never intended to provoke any - and I'm quite sure that you didn't either.

Best wishes,

Olly

[sharkmelley]

The key issue at long focal lengths is guiding accuracy.  Backlash can cause guiding problems in both the RA and Dec directions.  In addition, periodic error and other higher frequency "jitter" can cause guiding problems in the RA.  Periodic error correction can make a big difference though its success may depend on gear ratios in the gear train (the EQ6 has problematic 12:47 gear ratio which makes PEC less effective - I don't know about the EQ8). 

Backlash in the RA direction can be overcome by weighting the axis slightly heavier on the East.  In the Dec direction backlash can lead to oscillations where the guiding corrects in one direction, overshoots and then has to overcome backlash before it can correct in the opposite direction.  On my EQ6 mount the guiding can often take a few seconds to remove the backlash when Dec guide corrections change direction. This can be mitigated by deliberately misaligning the polar axis very slightly to intentionally induce some very slight Dec drift e.g. a drift of 1 arcsec per minute of time.  The guiding software can then be set up to make corrections in only one direction and the problem of oscillatory behaviour is removed.

Obviously, good guiding accuracy is much easier to achieve with a good quality mount but that doesn't mean it is impossible with a cheaper mount.

Mark