Still confused with mount selection

[DJ N]

Hi all,

Still tossing around ideas of equatorial mounts. Looking at purchasing an 8 inch SCT and mounting it to a GEM, preferably with goto. Looking at this great website along with other literature, the consensus seems to indicate that the HEQ5 mount seems ‘a lot’ better package than the CG5 (as a friend of mine put it, when he saw both of them side by side, it was like comparing a BMW to a Hyundai!!). The chief purpose of the mount is for visual use, but with a pal of mine and his ‘expensive’ camera gear, we are starting to dabble in quite a bit of astrophotography using my Dob so I have come to the conclusion that I need to upgrade (on top of this we now have access to a private farm about an hour out of Adelaide where the skies are pretty good – at least much better than Adelaide itself).

So the question which comes to my mind, which would be better,


HEQ5 Pro series mount (obviously wait for version 3 software)
Standard HEQ5 mount and fit Argo Navis (this then would make it ‘drive to’ rather than goto?).
Option 2 would probably turn out about the same price as the HEQ5 Pro, but my thinking would be that this would be a less complex system in terms of reliability. Would I be correct in assuming that the drive system of the standard HEQ5 would be less complex than the Pro series???? I would have thought the Pro series would have additional circuits etc… so more things to go wrong with it???

As a final thought, is the CG5 that much inferior to a HEQ5??

Oh by the way, I did consider the EQ6, IT IS MAMMOTH (so I have definitely dropped this one from the equation).

Would be great to hear peoples thoughts!

Cheers,

Daniel:help:

[Merlin66]

Looking at your needs... why not go for the full fork mounted SCT? It'll support your gear and give GOTO etc??????

[DJ N]

With a fork mounted SCT, I would assume something like LX90 or LX200? For astrophotography, would it be absolutely necessary for an equatorial wedge? I suppose the downside of a fork mount would be that you do not have flexibility for OTA changeover.

[Merlin66]

For short exposures, the al/az set up would work fine. When you build up confidence then you can make up a wedge to give extended tracking without field rotation.

[g__day]

DJN- some thoughts,

Using forks you'd need a field de-rotator for all but short duration photography.

Forks can be challenging to use if you you are photgraphing stright up, in terms of clearance at the bottom of the OTA and the fork for all your photographic equipment.

CG5 with goto (between $999 - $1,249 - flash upgradeable handcontroller version) are a variant of EQ5 mounts.

A goto EQ5 mount is likely to cost $1,699 or $2,199 HEQ vs $1,999 for a Goto EQ6 from Andrews!!!!

Of the EQ ranges I'd definitely slect the Goto EQ6 at that price - much more scalable for later use!

http://www.andrewscom.com.au/site-section-10.htm

Skywatcher Equatorial Mounts


HEQ5 Go-To has steel tripod legs and Skyscan Go-To Upgrade fittedNow $1699.00HEQ5 PRO has steel tripod legs, white in colour, Skyscan Go-To fac. fit. Now $2199.00EQ6 extra heavy duty equatorial mount with tubular steel tripod legsNow $1199.00EQ6 Go-To has steel tripod legs and Skyscan Go-To Upgrade fittedNow $1999.00

I have a CG5 with a C9.25 and a 80mm Megrez piggybacked on a pier. Its great for visual work; to be determined if the mount is stable enough for serious astrophotography loaded as it is!

The CG5 has Autoguiding (essential for long duration photography) but not Periodic Error Correction (PEC).

Its hard to find, but when I researched carrying capacity, cost, pointing and tracking ability (shame the post was lost in IIS, but still exists here http://www.astronomyonline.com.au/Default.aspx?tabid=107&forumid=24&threadid=37&scope=posts ) the carrying capacity of the CG5 is HIGHER than the more expensive Heq5!!!

EQ5 7 Kg, HEQ5 10 Kg, CG5 13 Kg

Those figures came from the manufacturers - so there is no veracity that some weren't being modest and others aggressive with their limits.

[DJ N]

Hi G_day,

Couple of questions.

1) Regarding the Goto upgrade fitted versus factory fitted on the Pro Series, apart from the white paint, what are you paying the additional money for?? Any ideas??

2) You mentioned that you have the CG5 mount. Any regrets?? Looking at Andrews site, they have the C8 SGT package for $2699. Seems like a good price for the setup. For the little photography we have done, most of it involves short duration exposures and then stacking. I suppose what I am getting at, the C8 package has been on my mind for a while, and it would be great to get feedback from users.


Cheers,

Daniel

[rogerg]

For SCT I'd be going with a fork mount, LX200. But I'm bias - I have an LX200's and am really happy with it's performance over the last 6 years, as far as I'm concerned it really is very near reserach quality - train the PEC, balance it right, then you have excellent precision etc. 40 minute exposures is testiment to that.

The thing I hate about GEM's is the meridian flip. Big pain for photography I think. I fear what the problems would be with plate solve's, causing problems for automation?

As for swing-through clearance - straight up isn't any problem at all with a wedge (probably is for alt-az), heaps of room on my LX in EQ mode. Looking south gets a little tricky, I can view the whole of the LMC but only just. But it can be solved by shortenning the imaging train, just needs $200 odd for adaptors.

Short exposure can be done without a wedge as other have said, but you really need a wedge.

I'm not sure on the cost comparisons.

You're right you can't change the OTA over with fork mounts. Guess it depends what you're planning to do if that's a problem or not. You can piggyback small-medium refractors.

That's my scattered thoughts/2c worth.

Roger.

[g__day]

DJN, I'm still learning compared to many more experienced folk here, but I asked your questions about 6 months ago, so what I found is

1) No differce accord to Lee Andrews - spray it white and charge more - no sense in that!

2) Almost no regrets within tthis mounts weight limits and price brand
- once I set up the mount as sited at Sydney - rather than its precise lattitude and longitude from google. With precise co-ordinates about one in three gotos would slew the wrong way and cause collisions between scope and mount - a real no no! Going back to default location fixed this perfectly!

Also I wish the mount took time from an internal clock or a PC connected to the hand controller, as I have mine in a fixed location so then a hibernate / wake-up would be all it needs to locate thing sprecisely each evening.

Too you need third party software for autofousing, guiding, goto control - all achievable at low cost but it would be nicer if Celestron bundled all this like Meade do, rather than you having to buy 3rd party add ons from scratch!

The manual lacks some detail. Two examples:

1) Once it has 3 or even 6 star alignment I presumer it would correct for cone (pointing error automatically) no only on GoTo's but on tracking! It doesn't!!!! On gotos it corrects very well, but then it just runs the RA motor at the rate of an hour hand, rather than running both motors and self correcting your alignment error from celestial south.

Another annoyance is that the mount then knows your alignment errors and allows you to correct it, BUT only when pointing at one of the dimmest objects in the sky that a new amateur might not pick correctly - Sigma Octans. I wish it could select a real bright, visible alignment star - e.g. Altair, Antares etc - slew to it pause for 5 seconds then slew off it with based on your alignment error from Celestial South and allow you to manually adjust the mount.

2) Entering date / time or other set-up paramters - you have to hit Undo to get into edit mode - not Enter as the manual says. Too the clock doesn't start (even though time is the second paramater entered) until all 6 or 7 parameters are supplied. So to be accurate add 60 seconds or so lead time and only press the final Enter button (for the current date) once your scope set-up is all complete.

So it has oddities and dumb limitations that you can mostly work around easily once you know they are there!

[netwolf]

Does the EQ6 from Andrews for 1199 have the new synscan stepper motors, so all you need to do is add the hand pad later on?

Regards

[anthony2302749]

There has been a lot of talk about the carrying capacity of the EQ5/CG5. The realistic carrying capacity of this mount is rated between 7 to10 kg. I know that Celestron sells the CG5 with a11” SCT, this weight a whopping 41kg well over the carrying capacity of the CG5. In practical terms it is unsuitable for astrophotography due to instability caused by to much weight, a small breeze will have the hold scope shacking all night.

I have use an EQ5/CG5 for astrophotography and from experience I would not put anything large the an ED80 plus camera on this mount (total weight about 6kg). The ED80/EQ5 would prove to be quiet stable and suitable for extended exposures times if the mechanic of the mount are good eg Periodic Error.

Final point, most EQ5/CG5 mount that I have seen and use have had some work done to improve the performance of the mount (see Astronomy Boy web site for more information). While the modification make the mount better I think the EQ5/CG5 have seen there day and the addition of electronic does not necessarily make them a better mount. The electronics are only as good as the person who is driving the mount.

As for the HEQ5 be it black or white in colour is an improvement on the EQ5/CG5 and is capable of carrying up to 13kg. The EQ6 is capable of carrying up to 18kg (a 12” SCT). I have not used a HEQ5 but I have used the EQ6 mount and all I can say is wow. The first night I used the mount all I did is a ruff polar alignment using the polar alignment scope followed by one star alignment after switching on the electronics. I then looked at about 6 or so Messier Object both east and west of the meridian using the GOTO and was pleasantly surprised to find all object with in the field of view (I was using a Skywatcher ED120 and a 22mm Naglar).

Astrophotography wise the HEQ5 and EQ6 are superior to the EQ5/CG5. On the second night out with the EQ6 I was able to image M8 unguided for over a minute with very good results, SEE IMAGE. (not bad considering I have only used the mount twice and I have yet to use my ST-7 as an autoguider). Both mounts offer improve mechanics, PEC train and auto guiding port based on SBIG ST-4 protocol plus with the introduction of Version 3 Firmware you have the ability to update the control software when needed.

Overall the HEQ5 or the EQ6 would be a better choice then the out dated EQ5/CG5 mount. Both the HEQ5 and EQ6 puts the realm of astrophotography with in reach and are a good stepping stone to the next level.

[g__day]

Nice photo Tony!

Something I always pondered - is the rated carrying capacity of a mount expressed as a measure of what upper limit the OTA + counter balances included it can carry? I always presumed it was not - that it talked only about the OTA limit. So if a mount says max load is 20kg - that is talking about the OTA alone - not 10kg for the OTA and 10kg for the counter-weights, but 20Kgs for the OTA and possibly 12kg for counter weights. Is this your understanding of the convention used to classify load capability for a GEM mount - to state only the OTA in the calculation?

PS

I took have gleaned that the 11" SCT on a CG5 is a strech - probably just capable under still conditions for visual work. So my C9.25 + 80mm Megrez on a CG5 is a real strech for astro photography - even extremely well balanced, aligned, on a rock solid pier and housed in a fully protected dome astro-lab. If I wanted to spend a bit more I would have gone the EQ6 route, but I wanted the cheapest possible, barely capable goto mount as a start to learn on - call it the trial piece. Meanwhile I read alot and ask folk about the Losmandy G8, 11 and Titan, the Vixen Atlux, the Celestron CGE and the Takashi EMM 200 or NJP as a serious step up from the EQ6 - at between 2 to 5.5 times its price (for the Titan). The Losmandy's below the expensive Titan I hear from owners have real exposure to motor burnout, but beautiful gears. The Vixen is back-logged waiting for the newest version of Atlux to come out and this sensational mount might be right at the limit of its significant capability to carry a C14 + ED80 as my ultimate dream set-up. An NJP could manage all this - and look what StronManMike has achieved with his 5" APO on an NJP, the CGE is newer than the Losmandy and has far cleaner lines and more carrying head room, but its gears aren't quite the quality of the Losmandy's I'm told.

But once you're into this quite high end equipment you may as well include a Astrophysics 900 GTO or a Mountain Instruments MI 250. If I won the lottery, sure I'd get a Paramount ME and put a 20" RCOS RC on it with $50K of imaging CCDs, but that's unlikely to happen - even in my dreams!

[anthony2302749]

[quote=g__day]Is this your understanding of the convention used to classify load capability for a GEM mount - to state only the OTA in the calculation? quote]

The answer to the above question is yes. Counter weight are not included in the calculation. Consider that the whole purpose of balance a EQ mount is to reach equilibrium between the OTA and Counter weight (centred on the polar axis) so that the mount can track smoothly without to much stress on the machanic.

If the EQ mount is equipped with a short counter weight shaft you will need more weight to reach balance if you have a heavy OTA. If the counter weight shaft is much long say 1/2 a meter you will need less weight to reach balance with the same OTA, but this may make the mount unstable.

So generally speaking, you may be able to balance a 41kg OTA using a 1kg counter weight if the counter weight shaft is long enough, but this would be very impractical.

So you should buy the best mount you can afford, ensuring that it has sufficient load carrying capability to carry all your gear with some room to spare. Also consider how this mount will be used in the future, because plans always change.

Final thoughts, this discussion has been about the load carrying capability of the EQ5/CG5, HEQ5 and EQ6. There are many other factor to consider when look at purchasing a mount, price being one but not always the best choice for quality, type of work you plan to use the mount for, type of OTA, autoguiding, ease of use etc.

[g__day]

Thanks Anthony, I thought my understanding was correct.

The C11 OTA is rated by Celestron to weight 13Kg, the exact stated maximum carrying capacity of the Celestron CG5 mount.

[anthony2302749]

Sorry misunderstood the question. What I was saying in my last disscussion is that counter weight are not included when talking about carrying capacity of a mount and I was not suggesting that the carrying capacity was based on the weight of an OTA. If that was the case then the CG5 can carry a scope as large as a 16" SCT but this would make the whole thing unusable for use.

When rating a mount it should not be based on how large a scope you can put on it but more about what is the realistic carrying capacity the mount can handle and still perform will within a certain limit. The upper limit of the EQ5/CG5 is 7kg. That means putting any thing heavier then 7kg would make it impratical, but not impossible for astrophotography. I say not impossible because through pereverance one can achive some very good results but why put yourself through such hassles.

If any one has any intention of using a EQ5/CG5 for astrophotography I would suggest that they keep the weight of their telescope and camera gear near the 7kg mark. I say this through experence you will get better tracking, hence longer exposure times and if you keep the focal ratio of your scope at around f7 or less you will get better star images (there is nothing like long f/ratio to show you the limitation of your mount).

Now to keep the record straight, the weight of the OTA on top of a mount does not indicate the carrying capacity of that mount. Stability is the true measure when it comes to carrying capacity.

[g__day]

Er the 16" Meade is 125lbs or 58Kgs - so its four times more than a CG 5 could carry, or more than twice what a EQ6 could carry by my understanding.

I agree that loading a mount to its maximum weight isn't likely to do wonders for your astro-photography. I presume if you are autoguiding well and your setup is fully protected from the elements and fully automated (so you never have to touch the running set-up) you can minimise the problem with a heavy load; not that it will do wonders to your bearings!

But that is just a theoretical mindset with no deep practical experience to field test it yet. Most people won't have an ideal set-up either so I'll experiment before I can even say it works for me!

With my well aligned gear - quite heavily loaded - I can leave it for three hours and a star at low magnificant remains almost dead centre, with auto-guiding this should be perfect and if the adjustments are very, very small and every say 15 seconds, I'd guess you could image to some degree on this?

The way to avoid all this is to get a bigger mount, like I say a goto EQ6 has to be a very capable, versatile and effective first platform to image from on a budget. My choice for a first Goto mount was easy, my second and/or third goto mount assuredly won't be!

[DJ N]

Thanks for all the great feedback, really appreciate it.

I read on one of the replies suggesting a load of up to 7kg would be OK for the CG5. Would this suggest the CG5 would be OK teamed up with the 8 inch SCT together with a camera (Nikon D2 weighs about 700g).

In addition, any comments regarding "reliability" of go to systems. Is an alternative solution a standard HEQ5 and fit Argo Navis to it. I assume you would use the tracking motors to slew to the correct coordinates?

Look forward to some more great feedback.

Cheers,

Daniel

[g__day]

Dan,

Suggest you talk to Lee Andrews at Andrews Communications and Steve Massey at MyAstroShop for their opinions and options, as well as folk here of course. I find these guys have the best entry level options for performing goto mounts.

Matt

[anthony2302749]

I have used the Argo with a EQ5 and it worked a treat the only problem is fitting the Argo as it may be a DIY job.