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Old 30-01-2019, 07:54 PM
NathanK25 (Nathan)
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Pairing a C8 with an alt-az mount...

This is a topic I kicked off under the Beginners Equipment forum, but given where its gone I thought it might be worth throwing it out to the wider Equipment Discussions brains trust...

Having become a victim of the axiom that the best telescope is the one you use, I've decided to try and sell my much loved Celestron Advanced Series CG-SGT and AP equipment, with the intention of using the proceeds to downsize to something more portable and simpler to set-up. My original thought had been to transfer entirely to something along the lines of a Celestron NexStar Evolution 6. I like the internal battery (not carrying around a power pack), the alt-az mount (no heavy counter-weights and less mount assembly) and integrated carry handle. However, on the Beginners forum I received the interesting suggesting of keeping my C8 OTA (aperture addiction, anyone?) and sell the rest to fund a new mount, perhaps a Celestron Evo mount (there seem to be a limited number of outlets in the US and UK who do sell them separately).

I'd be really interested to hear any advice on compatible single fork alt-az mounts for a C8 or any experience with the Evo mount in particular.

Many thanks.
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Old 30-01-2019, 08:17 PM
Ukastronomer (Jeremy)
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THEY DO sell them separately you just have to order them, I bought the package though as I wanted a SC, to find these two sites took me seconds, have you googled "Celestron Evolution Mount" as I did

https://grovers.biz/optics/home/7518...nt-tripod.html




Available in the UK, just Google, Try asking Simon at the Widescreen Centre,

I shop here for everything he knows me well

https://www.widescreen-centre.co.uk
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Old 30-01-2019, 08:27 PM
Wavytone
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Nathan I’d say what you propose will be unsatisfactory unless you choose a fairly substantial mount that tracks. There are sone options:

1. A CPC Celestron,
2. Meade Lightswitch
3. SCT of your choice on an AZEQ6 mount, or iOptrin iEQ45.

A few years ago I assembled a nice altaz push-to setup using a Losmandy AZ8 with encoders and tried several scope on it ranging from a 100mm f/7, 130mm f/7, 7” f/10 and 7” f10, and ultimately my MK91 which is a 9” f/13.

The conclusions I came to are:

1. Without some form of automated tracking a scope with a focal length > 1200mm rapidily bcomes a pain in the rear to use. While low powers are ok for high magnifications > 150X it’s tedious and at 200 bordering on impossible. Yet my MK91 can handle 600X.

2. The field of view at the scopes lowest pier is small, and locating faint objects can be extremely hard in some constellations where - particularly in urban light polluted skies - nearby bright stars are non existent.

While the addition of encoders solved the second issue it doesn’t sokeve the first and some form of tracking is necessary.

Ultimately I ended up buying an AZEQ6 Mount which I mainly use for visual observing with my current scope which is a 9” mak.
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Old 30-01-2019, 08:31 PM
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mental4astro (Alexander)
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Nathan,

The Celestron Evo mount is a very capable machine. It is all the same one mount for the 6", 8" and the 9.25" scopes. It is also a much more sturdy mount than the SE, and uses some bronze gears, not plastic ones.

Even the SE is still a capable mount. You need to get the mount of the 8" or 6" SE as these are the same mount between the two models. I had one of these with an 8" SCT, and it worked well. But if I had a choice between the two today, I would go with the Evo.

A third alternative is a single arm conversion of a CPC 11" or 9.25". These are the exact same mount between the two scopes, the difference being an additional set of spacers that hold the 9.25 scope. This CPC mount is even more robust than the Evo. I did this conversion to a CPC 1100 Deluxe mount just recently to take the 7" Russian Mak I now use. This scope weighs as much as the 9.25" OTA, but requires greater clearance around the focuser. Neither the SE or Evo mounts are suitable for this Ruski scope. You will find the thread I started of my CPC conversion here. This single arm conversion is still strong enough to take an 11" SCT! so an 8" SCT won't stress the mount in a fit.

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Power wise, the CPC does need a separate power source. For me this is not even a concern for what the mount offers me capacity and performance wise.

To find an Evo or CPC mount here in Oz, you just need to place a Wanted ad in the IIS classifieds as many people remove the OTA from the mount, and the mount is then doing nothing. That's how I found my CPC. You should be able to find either mount for about the same price too, and MUCH cheaper than trying to bring just the mount in from overseas!!! Also less expensive than an AZ-EQ5 or 6.

Alex

Edit: I am familiar with Wavy's 9" Mak. It is a BEAST of a machine, and nothing smaller than an AZ-EQ6 is capable taking it. His 9" Mak is over 10kg! If such a mount appeals to you, think carefully as this is also a BIG mount... Blooming great mount, but BIG.

Last edited by mental4astro; 30-01-2019 at 08:52 PM.
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Old 30-01-2019, 08:33 PM
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MortonH
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Quote:
Originally Posted by Ukastronomer View Post
THEY DO sell them separately you just have to order them, I bought the package though as I wanted a SC, to find these two sites took me seconds, have you googled "Celestron Evolution Mount" as I did

https://grovers.biz/optics/home/7518...nt-tripod.html


Available in the UK, just Google, Try asking Simon at the Widescreen Centre,

I shop here for everything he knows me well

https://www.widescreen-centre.co.uk


You do realise that Ice in Space is an Australian forum, yes?
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Old 31-01-2019, 05:14 AM
Ukastronomer (Jeremy)
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You do realise that Ice in Space is an Australian forum, yes?
I am Autistic not stupid

by providing links I was simply showing they are available separately
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Old 31-01-2019, 07:44 AM
Wavytone
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Nathan - if you want to put a C8 on a 1 arm fork modding a CPC mount as Alex described is a definite possibility. It’s definitely feasible as a home DIY job without requiring a machine shop.

There are some older threads here and on CN by people who have done that.
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Old 31-01-2019, 09:46 AM
brian nordstrom (As avatar)
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, some people aye ?

I appreciate your imput and why should where you are make any difference in the world ? .

Keep up the good work .

Brian.
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Originally Posted by Ukastronomer View Post
I am Autistic not stupid

by providing links I was simply showing they are available separately
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Old 31-01-2019, 09:48 AM
casstony
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You could advertise for a used Evolution mount; it's a good size for a C8. I prefer using the hand control but if you like the idea of wireless control get a more recent mount as they apparently have a stronger wifi signal.
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Old 31-01-2019, 04:50 PM
rrussell1962
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I am trying my Nexstar 8se OTA on the Skywatcher Star Discovery mount. The Skywatcher tripod is woeful, but I swapped it out for a Bosch Surveyors tripod from Bunnings for around $90. One snag is that the mounting is on the "wrong" side of the tube so the focusser is above the visual back. A 2 inch diagonal will not fit unless the focal reducer is used. The standard 1.25 inch visual back and diagonal is fine. The tripod needed a bit of work - spread limiter made from cheap chain but it is very steady - much better than the Celestron Nexstar mount. The "Freedom Find" absolute encoders make the set up very practical and very efficient in terms of power usage.
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Old 31-01-2019, 05:24 PM
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Originally Posted by rrussell1962 View Post
I am trying my Nexstar 8se OTA on the Skywatcher Star Discovery mount. The Skywatcher tripod is woeful, but I swapped it out for a Bosch Surveyors tripod from Bunnings for around $90. One snag is that the mounting is on the "wrong" side of the tube so the focusser is above the visual back. A 2 inch diagonal will not fit unless the focal reducer is used. The standard 1.25 inch visual back and diagonal is fine. The tripod needed a bit of work - spread limiter made from cheap chain but it is very steady - much better than the Celestron Nexstar mount. The "Freedom Find" absolute encoders make the set up very practical and very efficient in terms of power usage.
Did you just swap the legs and keep the Skywatcher tripod head? The mount base takes three screws doesn't it?
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Old 31-01-2019, 05:41 PM
rrussell1962
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I tried a couple of things Morton. Eventually as a first satisfactory fix I just made up a bolt with the correct thread and length to screw into the centre hole on the mount. It was tight enough that the base did not shift and move in Azimuth on the tripod head when I manually moved the mount or slewed. What I eventually ended up doing was buying a length of threaded rod and a couple of wing nuts and making a triangular plywood spreader for the legs to tension them against the chain. Works nicely. Does it make sense though?
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Old 31-01-2019, 06:26 PM
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Originally Posted by rrussell1962 View Post
I tried a couple of things Morton. Eventually as a first satisfactory fix I just made up a bolt with the correct thread and length to screw into the centre hole on the mount. It was tight enough that the base did not shift and move in Azimuth on the tripod head when I manually moved the mount or slewed. What I eventually ended up doing was buying a length of threaded rod and a couple of wing nuts and making a triangular plywood spreader for the legs to tension them against the chain. Works nicely. Does it make sense though?

Interesting. I didn't know the mount had a centre hole. I've watched the assembly video by Orion Telescopes in the US and that showed three screws from the tripod head into the base of the mount. I assumed the Skywatcher version was the same. A centre hole would make things easier. Can you remember the thread of the hole?

EDIT: In the Orion video you can briefly see there's a central hole but no mention is made of it.

Also, does the mount itself really support a C8 adequately?

Last edited by MortonH; 31-01-2019 at 06:38 PM.
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Old 31-01-2019, 06:58 PM
rrussell1962
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The thread size escapes me for the moment, odd because it is the same as the Vixen thread on the GPDX that I have. I do know it is imperial and almost but not quite M10 because that was my first fail! Does it adequately support a C8? For visual yes - a lot better than the standard Nexstar 8SE mount when attached to the Bosch tripod, with the supplied tripod it is good for an ED80 but nothing bigger. Mind you I did tighten the altitude clutch a bit. It actually works better with the 8SE than it does with my Skywatcher ED100 which was the reason I bought it! I assume because the 8SE OTA is much shorter. If you give me a day or two until I get some time off work I will post some pictures and more detail.
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Old 31-01-2019, 08:08 PM
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Hmm, imperial that's almost 10mm? Could it be 3/8"-16, the standard photo tripod thread that Skywatcher is using on their latest alt az mounts? I calculate that 3/8'"= 9.525mm. Let us know when you have time. Cheers.
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Old 02-02-2019, 07:53 PM
NathanK25 (Nathan)
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I very much appreciate the considered advice all round. After a few years absence, I'm very much looking forward to getting back in to observing again soon.
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Old 03-02-2019, 02:01 PM
rrussell1962
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Hmm, imperial that's almost 10mm? Could it be 3/8"-16, the standard photo tripod thread that Skywatcher is using on their latest alt az mounts? I calculate that 3/8'"= 9.525mm. Let us know when you have time. Cheers.
A couple of photos

The first one is the mount head, tripod and spreader. The second shows the cheap chain and bolts that I put through the outer part of the legs as a spread stopper - the tripod does not have one. The third is not good but shows the threaded rod (3/8" as you said) going into the mount head and secured to the tripod with a wing nut and mudguard washer. There is another wing nut and mudguard washer under the wooden spreader tray to tighten it against the legs which tensions the chain. For visual I find it a lot less prone to vibration than the standard nexstar tripod and mount. It would be interesting to mount the nexstar head the same way but the central hole on the head is used for a locating pin sadly.
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Old 03-02-2019, 02:40 PM
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So the head could be attached to a suitably sturdy camera tripod with standard 3/8"-16 bolt?
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Old 03-02-2019, 04:57 PM
rrussell1962
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Well, here is the bottom of the mount. Just bear in mind what I said about the focuser position given that the dovetail will now be on the right and not the left so the OTA is basically upside down from "normal" Also tightening up both the slip clutches is a big help.
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