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Equipment Discussions >> Mounts

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orlyandico
Postmaster
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Reged: 08/10/09

Loc: Singapore
Re: Recommend a mount for a new guy. new [Re: WadeH237]
      #5963871 - 07/10/13 11:08 AM

Wade, you forgot one thing - all the nights (and hair) you'll lose trying to fiddle with your entry-level mount.

Been there, done that, lost a lot of imaging time, and gotten nickel-and-dimed to death.


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Stew57
Carpal Tunnel
*****

Reged: 05/03/09

Loc: Silsbee Texas
Re: Recommend a mount for a new guy. new [Re: orlyandico]
      #5963889 - 07/10/13 11:18 AM

Orly is right. Skip the CGEM and get something better. Celestron still has not sorted it yet. I would get the VX before the CGEM. I can't speak for the Atlas as I have never had one, but the CGEM's PEC is broken and you stand a good chance of getting the DEC cogging effect with your mount. They may release a firmware ypdate to fix the cogging (beata right now but issues keep showing up) but I doubt they will fix the 8/3 error.

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Bill McNeal
sage


Reged: 10/07/07

Re: Recommend a mount for a new guy. new [Re: Stew57]
      #5966332 - 07/11/13 08:45 PM

Thank you all for your insight. If I decide to go with a new entry level mount, I will probably keep it for a while until I can go all the way.

I'm debating how to use the old CG-4. Is the mount and tripod usable with binoculars or camera? Otherwise if I get a new mount I can only re-use the counterweights--I don't know of other parts that can be transferred to a new mount.

I was considering buying the AVX, but then I read other threads here raving about the ZEQ25GT, about $130 more. What do you guys think of it compared to the CG-5 ASGT or AVX?


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orlyandico
Postmaster
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Reged: 08/10/09

Loc: Singapore
Re: Recommend a mount for a new guy. new [Re: Bill McNeal]
      #5966470 - 07/11/13 10:31 PM

The ZEQ25GT doesn't have permanent PEC, the AVX does. I think you can't really go wrong with either one, my preference tends to Celestron, because their software is great. I keep my CGEM around for that purpose, in spite of its terrible 8/3 periodic error, simply because the software can't be beat.

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Stew57
Carpal Tunnel
*****

Reged: 05/03/09

Loc: Silsbee Texas
Re: Recommend a mount for a new guy. new [Re: orlyandico]
      #5966506 - 07/11/13 10:53 PM

The software on the Celestron is great but the Atlas has EQmod that makes up the difference. While many say the ZEQ25GT can be overloaded without problem I am hesitant to recommend that to someone. If Celestron ever fits the CGEM with AVX integer servos the CGEM will be hard to beat. Until then the atlas looks good. If the Atlas is outside your price range they do come up used when people upgrade.

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orlyandico
Postmaster
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Reged: 08/10/09

Loc: Singapore
Re: Recommend a mount for a new guy. new [Re: Stew57]
      #5966539 - 07/11/13 11:18 PM

For someone starting out, I would not recommend the CGEM or Atlas, simply because they weigh too much and can discourage the beginning imager.

Hence I'd say AVX or ZEQ25GT, which should be good enough for focal lengths in the 600mm range, guided. The only advantage the CGEM and Atlas would give is more payload, but it's still going to be a challenge imaging at much longer FLs on these mounts. That's where the "buy the best possible mount" comes in.

But you can spend years imaging at 600mm.....


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Falcon-
Post Laureate
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Reged: 09/11/09

Loc: Gambier Island, BC, Canada
Re: Recommend a mount for a new guy. new [Re: orlyandico]
      #5966772 - 07/12/13 02:35 AM

Not having had either the AVX or ZEQ25 in my hands I have to base this solely on comments of others on the forums here who have used them, but my impression is that the ZEQ25 would be the beter astro performer for the weight loads you are looking at. If I was in your shoes I think I would go ZEQ25.

There you go, ask a simple A or B question, get 12 different answers from the forum. Glad we could help you "decide"


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Bill McNeal
sage


Reged: 10/07/07

Re: Recommend a mount for a new guy. new [Re: Falcon-]
      #5966803 - 07/12/13 04:01 AM

Thanks again orlyandico and Falcon. I couldn't find any posts describing why long FL is harder on tracking; can someone point me in the right direction?

Does this mean my C4R with 1000 mm FL has too high a FL, and SCTs are out of the question for beginner mounts?

How do you know the max FL usable for the AVX is 600 mm? I don't see it on the specifications page.


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orlyandico
Postmaster
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Reged: 08/10/09

Loc: Singapore
Re: Recommend a mount for a new guy. new [Re: Bill McNeal]
      #5966807 - 07/12/13 04:13 AM

hi Bill,

the longer the focal length, the smaller the pixel scale. e.g.

http://starizona.com/acb/ccd/calc_pixel.aspx

in layman's terms, long FL usually implies greater magnification - which then requires the mount's errors to be less. You can see this for yourself - your mount is much more "jiggly" at high magnifications than at low ones.

About the 600mm.. I am just throwing that out as a rough rule of thumb. I know some people image at 1280mm (C8 with 0.63 reducer) with a CG5-ASGT, so it is certainly possible.

But if you stay below 600mm range, you will enjoy a higher success rate and be less frustrated.

I am sure there are a lot of people who would take offense at my statement to stay under 600mm with the CG-5 or AVX. Sure anything is possible, I am just speaking from my own experience. If you keep your expectations modest, your imaging will be far more enjoyable.

The C4R is an achromat, I suspect you will be less than happy with the results from that OTA for astrophotography (namely a bright blue halo around all the bright stars). It would probably be OK in a pinch, and if you shoot narrow-band it will work. It is rather slow though at f/10 and would require long exposures.


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Bill McNeal
sage


Reged: 10/07/07

Re: Recommend a mount for a new guy. new [Re: orlyandico]
      #5966812 - 07/12/13 04:19 AM

Thanks again orly! I'll keep those issues in mind and consider a new OTA in the future. I like your avatar. Is it from Fallout?

Also, I read some GoTo mounts are not hand movable, which I need for terrestrial viewing. Does ths issue affect the CG-5 ASGT or AVX?


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Falcon-
Post Laureate
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Reged: 09/11/09

Loc: Gambier Island, BC, Canada
Re: Recommend a mount for a new guy. new [Re: Bill McNeal]
      #5966836 - 07/12/13 05:02 AM

As already said the problem is that if you have a tracking error that blurs the image by two pixel at 500mm it would blur the image by four pixels at 1000mm (twice as bad). The actual error is the same but it becomes more obvious at the longer focal length.

Of course this also means, going in the reverse direction, that if you have a 2 pixel error at 500mm then it will be less then 1 pixel with a 200mm camera lens (invisible).

With my own CG-5 ASGT I did imaging at 28mm, 50mm, 300mm, 912mm and 1370mm. It was (and still is!) very easy to get good results up to 300mm. At 912mm (with an admittedly heavy scope) and a bit of tweaking I could get somewhat consistent results. At 1370mm I had a very hard time getting any good results.

I was able to adjust the mount a bit and then clean it and re-apply grease and improved the performance somewhat, but never to my satisfaction at 1370mm. I purchased my used CI-700mount (an old mount, mechanically a bit better then the CGEM/Atlas, but less sophisticated in motors/control) to give me more reliable performance at the longer focal length.

Now I am given to understand the AVX improves on the old CG5's performance in guided imaging by refining what is essentially the same physical design.

So based on my single example I would put the "easy" imaging threshold for a CG5 at ~600mm, and useable imaging threshold at ~1000mm. As already said other people with longer focal length scopes had better luck then I did. I would expect the AVX to raise both the "easy" and "useable" numbers due to it's improved design, but the improvement is, at a guess, likely in the 25% higher range, not the 100% higher range.

The ZEQ25 has a different physical design, one that SHOULD eliminate the bigest problem I had (smooth guiding in the DEC axis) so I actually expect it should perform better at longer focal lengths then the AVX. Key words here are "expect" and "should"

Quote:

Also, I read some GoTo mounts are not hand movable, which I need for terrestrial viewing. Does ths issue affect the CG-5 ASGT or AVX?



A beter way to put this is that GoTo mounts loose track of their position when you move them manually. You *can* move them, it will just confuse the goto computer (it still thinks the mount is pointed wherever it was before you released the clutches). Since you will not be using the go-to fuctions during daylight anyway this hardly matters. To move the mount you release the clutch for each axis and point it where ever you like. Tighten the clutches back up again and you can again use the hand controller movement controls for fine-tuning location (just not the go-to until you re-calibrate).


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cn register 5
scholastic sledgehammer


Reged: 12/26/12

Re: Recommend a mount for a new guy. new [Re: Falcon-]
      #5966864 - 07/12/13 06:05 AM

My experience with the AVX and CG5 is that the AVX is quite a lot better. I've used it with a 500mm Fl ED retractor and a 1350mm RC6, it seems to be able to track and guide well enough for me with both OTAs. By the time the RC6 has a guide scope, focuser filter wheel and two cameras it's up to 25 lbs in mass so getting pretty close to the maximum limit.

I can't comment on the other scopes mentioned because I haven't used them.

Chris


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orlyandico
Postmaster
*****

Reged: 08/10/09

Loc: Singapore
Re: Recommend a mount for a new guy. [Re: Falcon-]
      #5966865 - 07/12/13 06:05 AM

I believe the issue with "hand moving" is the manual slow motion controls.

None of the new GoTo mounts have hand slow motion. If that is a hard requirement for you, the only option is a Vixen Great Polaris D2 (GP-D2) with the manual clutches and the Starbook-S controller.

This would provide both GoTo and manual slow-motions. You would still lose GoTo sync if you move the mount manually (very few - very high-dollar - mounts can keep track of their position even if you move them manually).

If you need something for daylight use, keep your existing CG-4. Have someone weld an aluminum tab to where the broken-off bit is. No sense spending big bucks looking for a GoTo mount that also has slo-mos when you already have a mount that has slo-mos.


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cirrus1500
member


Reged: 04/09/13

Loc: California
Re: Recommend a mount for a new guy. new [Re: orlyandico]
      #5975446 - 07/17/13 04:11 AM

Very useful thread full of good advice!

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cirrus1500
member


Reged: 04/09/13

Loc: California
Re: Recommend a mount for a new guy. new [Re: orlyandico]
      #5975451 - 07/17/13 04:22 AM

Orlyandico,
I notice that your location is in Singapore. Do you have any idea if the celestron CG5 or AVX can be used at low latitudes ? I remember the AVX's specs say it can be set to 0, but i am not sure if its practical. Celestron also mentioned that by removing a part from the CG5's head, it can point lower but did not mention how low. I plan to use the mounts at around 10 to 13 degrees lat. I am considering the CG5 since the price dropped significantly after release of AVX. If not usable, i may go for the AVX. Thanks in advance for your reply.


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orlyandico
Postmaster
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Reged: 08/10/09

Loc: Singapore
Re: Recommend a mount for a new guy. new [Re: cirrus1500]
      #5975454 - 07/17/13 04:40 AM

I believe the CG-5 can be used at low latitudes. There are folks here with Vixen GP family (which the CG-5 is based on) and it works fine, they do need to use a pillar so that the CW and weights don't hit the legs.

But I personally don't have a CG-5 or AVX. My CGEM cannot go down to low latitude so I had to have a wedge machined for it.

I don't see a problem with 10 degrees. The CGEM at least goes down to 15 degrees and the remainder can be taken up by putting a brick under one tripod foot.


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cn register 5
scholastic sledgehammer


Reged: 12/26/12

Re: Recommend a mount for a new guy. new [Re: orlyandico]
      #5976611 - 07/17/13 06:44 PM

AFAIK the AVX is specified to go to 7 degrees but from a look at mine the latitude adjustment can go to 0 degrees, maybe a bit less.

The reason for the 7 degree specification seems to be because the counterweight hits the tripod legs but if you have a narrow pier instead of a tripod you should be able to get to a much lower latitude. Orlando might be able to run it in Northern or Southern hemisphere mode!

Chris


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PhilCo126
Post Laureate


Reged: 01/14/05

Loc: coastline of Belgium
Re: Recommend a mount for a new guy. new [Re: cn register 5]
      #5979377 - 07/19/13 08:57 AM

With new versions of several mount on the market, there'll be an increase in second hand EQ-6 and CGEM equatorial mounts

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beanerds
sage


Reged: 07/15/08

Loc: Darwin Australia
Re: Recommend a mount for a new guy. new [Re: orlyandico]
      #5980909 - 07/20/13 05:18 AM

No sorry , 'Zinc Diecast' is almost impossible to weld , I would put it in the "Parts" cupboard and grab a nice new Ioptron IEQ30 goto .perfect mount for that nice C102 OTA .
Brian.
Quote:

I think a new tab can be MIG or TIG welded where the original one broke off. These things are aluminum so arc welding won't work. So if you can find someone local who can weld a new tab on for beer money, go for it. But if the welding would cost too much... you'd be better off buying.

The mount in its current condition is worth probably $50 - $100 tops, so not worth selling.

And.. I don't think it's a CG-5. Probably a CG-4. The CG-5's all came with a Vixen dovetail clamp. What you have doesn't have any form of dovetail clamp.




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Bill McNeal
sage


Reged: 10/07/07

Re: Recommend a mount for a new guy. new [Re: beanerds]
      #6000301 - 07/31/13 05:02 PM

Thank you all for your input. After much internal debate and anguish I'm leaning toward the ZEQ25, primarily for its light weight.

How much of a benefit does autoguiding provide? The autoguider kit I found costs as much as the mount!

It appears this mount doesn't include a dovetail bar. Is the Vixen type required to mount my Celestron C4R f/10 OTA to it?


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