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C8 questions


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it will be no surprise to most that I'm debating an upgrade - I've mentionend it before. I think a dob will be a struggle for me in terms of storage and moving around and transport, since I'm energy-limited. I keep coming back to thoughts of a C8. I've just noticed one for £350 s/h, which seems a fair price? But that is OTA only, which leads me to:

What are my mount options?

I don't want goto. I spend my life with computers, I couldn't stand it.

I guess I could go pure manual, but I get the impression that gets tedious real quickly with longer focal lengths.

So it seems I would need tracking. Can I get a suitable tracking mount? I have no idea about this.

What sort of money am I talking anyway?

Is the C8 even as easy to move and use as I'm expecting?

I keep planning to wait 'til SGL8 when I can look at some scopes and maybe try some things, but the fever keeps tempting me...

If anyone has thoughts, cautions, alternatives or just common sense, I'd be happy to hear it!

Thanks

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If you dont want a Goto then consider a motor driven equetorial such as CG5 or EQ5. In theory you will get away with a single motor on the RA axis but a 2 axis version is more conveniant. Second hand I wouldn't want to pay more than £200 for a near mint version

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If you dont want a Goto then consider a motor driven equetorial such as CG5 or EQ5. In theory you will get away with a single motor on the RA axis but a 2 axis version is more conveniant. Second hand I wouldn't want to pay more than £200 for a near mint version

Thanks astrofox. Just to confirm - was that £200 for the mount or the OTA?

One other thought - what else would I need? Diagonal and finder, anything special to mount with? Anything else I've not thought about? ....

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I think £200 would get you a mount driven on one axis, maybe two. You will need a diagonal and finder if the optical tube does not come with these. It will also need to be fitted with a dovetail bar to fit a Skywatcher / Vixen type mount so that might be another "extra" if not already fitted. Get a mount with steel legs not the aluminum type.

The scope tube itself would be additional to the above costs.

With SCT's a dew shield is almost mandatory in our climate as scopes with glass at the front end (like SCT's) are dew magnets.

Oh, and some eyepieces, if you don't already have some.

The C8 tube is light enough but the mount / counterweights adds quite a lot. I reckon an EQ mounted C8 will weigh around about as much as an 8" dobsonian would.

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A C8 OTA is as light as it gets for an 8" telescope. The early orange models were a bit variable in optical quality and suffered a bit more with image shift than the recent ones. Some were incredibly good though and represent good value. They sit quite happily on Vixen Super Polaris or GP mounts, both of which often come up for sale quite cheaply. I have one of the C8SE models and couldn't be more plesaed with it. :smiley:

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My C8 is very stable, being fork mounted, and is non goto, it tracks in RA using a 9 volt battery, so I have the best of both worlds - light, compact and portable and a very simple, trouble free set up. Something like a telrad, dew shield and CG5 or EQ5, as mentioned will be useful other upgrades, if required,could follow as and when you can.

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My C8 is very stable, being fork mounted, and is non goto, it tracks in RA using a 9 volt battery, so I have the best of both worlds - light, compact and portable and a very simple, trouble free set up. Something like a telrad, dew shield and CG5 or EQ5, as mentioned will be useful other upgrades, if required,could follow as and when you can.

I see from your signature that you have a C8 Celestar. I used to have one of those. It was the most portable 8" scope I've ever used and gave me my best ever view of Saturn during a memorable evening a few years back. Definitely a scope I wish I'd held onto.

I guess the current equivalent would be the Nextstar 8SE.

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I think that would be correct John, the Nexstar provides a combination between old and new design - so is effectively a successor to models such as the Celestar, which at the time, was marketed at affordability. The Celestar was only available for a few years in the mid 1990's, so the Nexstar altaz series has been a consistently popular and successful design, as it was first introduced around 2006.

Mine to has provided some incredible views of Saturn. I had considered certain modifications such as changing the mount to a CG5, but I am pleased that I have kept it the way it is because quite frankly, I like the ease of setting up and use and for many reasons intend to continue enjoying using it for a long time to come.

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Just like to add for the record, gleened sometime ago from Rod Mollises blog, that I believe the Celestar was only in production between 1996 and 1998. For those of you that do not know, his website is worth a vist for anyone wishing to learn more about the history and development of the SCT.

Just google Uncle Rod's Astro Blog

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Thanks Iain and John.

Let me put this another way - I really enjoy what I have right now which is an ST80 on a purely manually AZ. But, I want more aperture. What do I do?

I'd like to keep a purely organic, powerfree setup.

If that will be restrictive (isn't an EP change at x250 going to be impossible?) then okay I may have to look at tracking - although the dob mob seem to manage this problem okay.

But, my feeling is that a 200mm dob would be an effort for me to move and to load into the car and so on. Just a guess from the specs and pics of them, as I've never seen let alone touched one.

Hence my thinking C8. There are many people on here who have had theirs for years and years and are still very happy.

But, a C8 SE doesn't feel like it would suit me. Ohhhhh botheration :icon_scratch:

Unfortunately Bristol astro soc doesn't really have a members' club night, they have open-for-the-public-to-use-their-big-scope nights so it's not easy to try some stuff out.

Unless I wait for SGL8 - which would be logical, and would see me through a full season with my first scope - but that's aaaages away! ;)

Don't get me wrong your feedback has been very helpful. I know a lot more now - but not enough to get my head around the options and make a decision yet! Oh I'm hopeless! :D Still there's no rush...

Edited by KevUU
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The C8 packs a real punch with 8 inches of aperture but in a package of only about 5.5kg and being short makes it easy to mount, but also easy to view once on the mount as the EP doesn't move much!

You can eek out about 1.3 degrees from a longer FL EP or a bit more with a focal reducer, so it helps to have a tracking mount, but piggy backing a finder scope should work just as well. I use an 8SE from poorly LP suburbia with a Telrad which works well, although my needs for the Telrad don't extend much beyond alignment and brighter objects because its just hard to find anything faint naked eye here. At a dark site I expect it'd be a whole lot more useful.

The SE mount is computerised (with no ability to slew with using direction buttons) but is pretty easy to use and with a little experience can be setup in minutes. The biggest downside being the requirement for power. There is a little focussing wobble as Celestron is a little keen to under mount .... but as the guys have posted above, there are loads of mounts that will carry the C8 a lot more comfortably than other scopes with similar capabilities.

Regarding accessories, you will want a dew shield. And probably a longer FL EP or two as the focal length of a C8 is very different to an ST80 :D

Btw, uncle rod's blog is always a good read!

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The C8 packs a real punch with 8 inches of aperture but in a package of only about 5.5kg and being short makes it easy to mount, but also easy to view once on the mount as the EP doesn't move much!

That's exactly what I'm after! Really, really want to avoid goto though. It's just not for me.

Regarding long EPs, I have a 30mm vixen which is good enough for now, and was figuring I'd be wanting a not-too-expensive wide 2" EP with the new scope, if I ever take the plunge.

Thanks Dunkster :)

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For the avoidance of confusion:

I realised that I have no idea what I want and even less idea what I'm doing, so I have framed a slightly more general question in the Getting Started Equipment Help and Advice area: http://stargazerslounge.com/topic/170452-looking-for-an-upgrade-not-sure-what-to-do/

So if anyone feels like they have thread de-ja-vu, that's why.

(When I started this thread I stupidly (and perhaps arrogantly) thought that my 8 months experience and a half-century DSO viewings meant I had some idea of what I was doing, and just needed pointers. Seems not. Hi, my name's Kev, and I'm still a novice.)

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The universe is very old, we're all novices :cool:

However, those of us using SCTs in this generally damp climate are relatively few and far between compared with the Dob mob. There are advantages and disadvantages to all types of scope, it's a question of appreciating, understanding and living with them. Typically I have limited viewing time and opportunities so the dew isn't a big deal for me. Physical dimensions and contortions are!

Another point regarding EPs...shorter f/ratio scopes become much more demanding on EP choices, so while you can get away with less expensive EPs, observe how many of the guys and gals with fast scopes have an armoury full of pricey TeleVue EPs and coma correctors, etc. Soon eats up the difference in price between them... :D a C8 would be happy with an SW aero at a fraction of the price, but a Vixen should work well too...SCTs aren't that fussy!

I bought my C8 used and they can be a great buy at the right price ;)

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Just like to add for the record, gleened sometime ago from Rod Mollises blog, that I believe the Celestar was only in production between 1996 and 1998. For those of you that do not know, his website is worth a vist for anyone wishing to learn more about the history and development of the SCT.

Just google Uncle Rod's Astro Blog

Also worth a look is his Buyer's Guide to Used SCTs which can be downloaded free from his site here.

James

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I think the C8 is a wonderful "little big scope." I have had it for over 17 years, so it is doing something right. It sits comfortably on my Vixen GP mount, and I set it up easily in 5-10 minutes depending on whether I want to do a decent polar alignment or just point the polar axis north (good enough for visual tracking. The OTA weighs just 4.7kg, and I can easily transport it by car to any location I want (in 1999 I took it along on a camping trip to France to see the eclipse, no worries in the Peugeot 106 we had). I have a dew shield which is sufficient on most nights, and a dew ribbon for really humid ones. I added a home-brew 16x70 right-angle correct-image finder, which makes life a lot easier in terms of finding things. I added a 2" visual back and diagonal to increase the FOV some years. This is very useful.

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Cheers again Dunkster. What you say resonates somewhere with me - I don't know why but the C8 route feels righter. We'll see.

The universe is very old, we're all novices :cool:

So I see! Also, pride comes before a fall and humility comes next. So another universal lesson taught to me by, aptly, the universe. ;)

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I think the C8 is a wonderful "little big scope." I have had it for over 17 years, so it is doing something right.

Thanks Michael. I have to say, it was reading your observing reports, and then your happy birthday dear C8 post, that put the thought in my head to start with :)

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KevUU,

I am not sure how the used equipment market is in the UK but here in the states I've gone to obtaining most Astro-Items used. At first, when I became more serious about Amateur Astronomy I bought a GOTO Meade LX90 8" but found I preferred a manual or RA driven setup and a star hopping mode of viewing. So the following are just based on my personal preferences but may be similar to yours right now. I have found for manual observation with a longer focal length telescope I prefer a GEM mount since once you have the mount polar aligned and the object in sight, you can just track manually, or with a simple RA drive, by moving the RA control. I bought used both a C9.25 and C8 and eventually sold the C8 which I now regret as I get older because the C8 is considerably lighter and easier to set up with a lighter mount. For a mount I prefer and use a second hand Vixen GP(Great Polaris) mount with a single MT1 RA drive and SD-1 controller. You can get these with a simple clutch that allows you to switch between manual and tracking mode. With the narrower FOV(Field of View) that you have with a C8 versus your 80mm scope(Great scope) I think you will want to have the motor for tracking eventually. The older Vixen mounts are great (the SP Super Polaris or the GP), and here in the states you can often find them for $250 to $400 dollars used.

Note: For quick setups I also use a manual Alt Az Mount and for my C9.25 I use a GEM mount made by Losmandy (G-11) which hs a great push-to clutch mechanism (But this would cost 3 to 4X a GP mount and is not required for a C8. If you had and wanted to spend more a lighter version of the G11 is the Losmandy G-8)

A used C8 can be found for $300 and up here depending on the vintage. I prefer the ones made in the mid to late 90s. You will want a flexible dew shield and as mentioned you will want Eyepieces in the 15mm to 32mm range which are also fine for wider field of views with your 80mm scope. One thing to consider ahead of time is the time you plan to spend during a night of viewing and your climate. The 8" SCT requires more time to cool down to get a stable view and the amount of time required increases with aperture. If you want to be set up quickly and view for just one to two hour periods at a time, for example, you might prefer an 100 to 125 mm refractor in the f/8 to f/10 focal ratio range(my preference now). The targets I find where a larger aperture SCT or reflector is preferred are faint Nebulas and Globular star clusters. If you want to check out the extensive arguments between refractor, reflector and SCT enthusiasts check out the equipment forums on www.cloudynights.com, It can be informative and also amusing. The C8 is a great scope and personally I am working slowly to reduce my equipment down to a 90 to 100mm refractor and an 8"/200mm SCT (most likely a C8) as I approach retirement. I still use my 8" LX90 occasionally.

The best thing to do at his point would be to become more involved in your local astronomy club and check out other equipment in person. I wish I had done this earlier and it would have saved me time and money.

Regards,

Pete

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Pete,

Thanks a lot for that very detailed response, I appreciate your taking the time. It's becoming increasingly clear that I really need to get hands on some of the options and see what feels right for me. In the meantime I'll no doubt be reading and re-reading everyones advice and chewing it all over in my head ad nauseam ;)

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Well I have a possibility to buy a Celestar mount for a C8, which would leave me needing a C8.

What I can't work out, since most C8 would seem to have dovetail mountings these days, is how to mount it onto a fork mount... I'm sure this is simple but I can't find an explanation - can anyone help?

Sorry if this should be obvious...

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Kev this image illustrates the fixing point position for the Celestar fork mount onto the ota.

post-22819-0-90150900-1356017306_thumb.j

The optical tube should include as a standard feature,fixing bolts attached at various positions to accept different mount options. It should therfore be straight forward to connect. I have removed and returned mine onto the mount without any issue.

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