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Hi, Folks

 I am only a few weeks into astronomy and started off with a Celestron 9.25" Evo on the standard AZ mount. I guess with hindsight this wasn't the best place to start and also with hindsight I would have done better to have bought a GEM mount. Anyway, lesson learned and at 71 years old I have to speed up the learning process compared to younger enthusiasts :) I have 2 issues. 1/ Its a pain dragging the scope out into the garden and setting it up every time I think the fickled weather might be obliging. 2/ I now know that the mount I have is useless for long exposures and a wedge is fiddly to get polar aligned.

My question is, though I gather wedges are a PITA to setup etc is if I was to build or buy a pier for the backyard and use my existing mount + a wedge is this a reasonable way to go? Though it's fiddly to set the thing up once set I could leave the mount, wedge, etc covered up and would just need to drop the OTA on when I wanted to use it.  Is this reasonable or am I missing something fundamental down near the bottom end of my learning curve :(

Any advice much appreciated and don't feel you have to spare my feelings :)

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Having also just restarted astronomy with a recently acquired Celestron-8 (old school mid '70s vintage) and also on the other side of 70, I feel the same learning curve. My new scope is equipped with a wedge, and looking at it and reading your post, I wonder if I might add a rotating connection between the tripod and wedge in place of fixed screws.  In theory, once level and secure, I should be able to rotate the wedge and scope for the polar alignment, then lock that part and get on with the actual polaris alignment.  My previous scope was a 10 inch Dobsonian, which did not care where North was LOL.

comments?

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13 hours ago, G4EQZ said:

 I have 2 issues. 1/ Its a pain dragging the scope out into the garden and setting it up every time I think the fickled weather might be obliging. 2/ I now know that the mount I have is useless for long exposures and a wedge is fiddly to get polar aligned.

The most obvious answer to that is an observatory, but that may not be an option. Other solutions are

1. A roll-away shed, which generally is much smaller than an obsy.

2. A pier where the mount can be setup permanently, you just remove the ota every time.

3. Lucky imaging with your current setup. Have a look at this chap's site (but note that he has much faster optics)

http://www.astrokraai.nl

4. Bite the bullet, sell your current equipment and invest in an eq mount plus a refractor, to get a portable-"ish" setup.

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Hello G4EQZ,

With a name like that you should be well used to constructing your own stuff !!

1. Re: " Its a pain dragging the scope out into the garden and setting it up every time "

I have this problem. I am in the process of finding a way to setup quickly and accurately. I will be posting my effort in the DIY astronomer section.

2. Re:  "A pier where the mount can be setup permanently ... "

A pier is excellent BUT commonly available mounts, like mine, are not exactly weather proof. I would be averse to keeping these things outside (even if they are covered) as they are not designed to be subjected to the "huge" changes in temperature and humidity. In my case the temperature range is from 47C to -5C. Dew point from 6 to 9C to -5C (condensing atmosphere ). Remember, most of the time these mounts are not used. We need Mil Spec stuff !!

3. Re: Piers.

They are made out of all sought of materials and sizes.  What advice can I offer ? Think of a shaft that delivers power and consider the materials used in making these shafts.  These materials will be eminently suitable, in pipe form, with which to make a pier. If you have a mate in the refrigeration business then a short length of  "Ammonia Pipe" will be a good choice.

4. Re: " though I gather wedges are a PITA to setup ... "

Not Really. A little bit of practice will fix all !!

73's

Jeremy.

 

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My honest advice: if this is for long exposure deep sky imaging do not throw any more money or effort into the fork mounted SCT. A very small number of people do get them to work but the vast majority of those who try to do so give up on the idea (as I did myself.)  Indeed, of the people I know who did succeed in getting them to work, all but one have still moved over to GEMs. I know this isn't what you want to hear but when Ian King gave me the same advice fifteen years ago I wish I'd listened!

You don't specify your purposes in thinking of a wedge but, since it isn't necessary for planetary imaging or at all desirable for visual, I assume you're wanting to do long exposure deep sky imaging? Also, be aware that a fork mounted SCT loses most of its charm when wedge mounted. All that lovely convenience of position and eyepiece access goes out of the window.

To do DS imaging at the long focal length of a C9.25 you are going to need a very co-operative mount indeed and I doubt that the Celestron mount will ever be that. I would think again, favouring GEM and short focal length scope.

Olly

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Nothing wrong with wedges on a fixed pier - the big LX200s are mounted this way for observatory installation.

However in your case you should forget the wedge. AFAIK the Evolution mount is not ideal as a deep-space imaging mount, any more than the C9.25 is ideal as a deep space imaging scope. The wedge costs around 400 pounds, and you would be better advised to invest this sum toward a GEM mount like an AVX or HEQ5.  Then you can put the C9.25 on it and demonstrate to yourself how grim a scope of this FL is as a deep space imaging scope.  Then start saving for a small refractor.

OTOH if you want to do planetary imaging, use your present setup with an astro planetary camera. It will work just fine - maybe not as fine as a CPC925, but well enough.

 

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Posted (edited)

Hi All,

 Thanks for your advice. I suppose to some extent having just forked out £2.3k on the 9.25 Evo I am trying to find a way to (justify) keep it rather than taking a big hit on a trade in.

The setup issue every time I want to use the scope is a separate issue of course from its suitability. An observatory is not an option as I don't have space and other hobbies (ham radio antennas) already clutter up the small garden and since I denied "she who must be obeyed" a rotary clothes dryer on the grounds of space it would be a difficult argument :)

 I may go for the pier option anyway, at least when weather permits  I can leave the mount out covered up for a few days or weeks and perhaps get it to accept a rotary clothes dryer when it's not needed for astronomy :) Tips for the best materials were welcome thanks, Jeremy, and I have a mate into that sort of stuff so will ply him with beer to see what he can suggest, then some more beer to get him to volunteer :)

Medium term I think I am going to have to accept there is no one size fits all scope/mount and get my feet wet using the C9.25 for what it's intended for - planetary etc I assume. Further down the road, I guess I am going to have to bite the bullet and get a good GEM mount (EQ6 Pro?) and then perhaps a retractor so I can have the best of both worlds.  Eventually, I would like to do some DS imaging but need to exercise a little more patience and learn to walk before I run.

For now, I will attempt to fight off the impulse to indulge in some "retail therapy" and avoid the wedge, as already pointed out it will go a good way towards the cost of a reasonable GEM. There is a second hand EQ6 Pro with Rowan belt mod (whatever that is) going for £800 fully serviced etc which I am tempted to buy - anybody willing to put me off is welcome?

Cosmic Geoff, you said the c9.25 was a grim deep space scope. Is this an optical issue? just the long focal length, mechanical stability or what.  Bear in mind I am pretty green and as with most things the best lessons in life are often expensive but since I already spent the money it's best if know where I went wrong so I don't do it again :)

Anyway, thanks again to everyone for their advice. Not always what you want to hear if you screwed up but what you need to hear to move on and make better decisions in the future.

Cheers, 73's and Clear Skies ... Keith

Edited by G4EQZ

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3 hours ago, G4EQZ said:

Hi All,

 Thanks for your advice. I suppose to some extent having just forked out £2.3k on the 9.25 Evo I am trying to find a way to (justify) keep it rather than taking a big hit on a

Cosmic Geoff, you said the c9.25 was a grim deep space scope. Is this an optical issue? just the long focal length, mechanical stability or what.  Bear in mind I am pretty

It has a long focal length and a narrow field of view, which I'm told makes it difficult to use for imaging, compared with a small short focal length refractor. In practice, you could image small galaxies with it, while a lot of other things will fail to fit in the FOV.  If you have Stellarium and some camera specs you can see this for yourself by modeling what various things look like in the camera frame.

I have played around with deep space EEVA using a Startravel 102mm f5 refractor and a ASI120MC camera, neither of which I bought for this purpose.  Much easier to manage than using a f10 SCT.

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6 hours ago, G4EQZ said:

Rowan belt mod (whatever that is) 

It means that the cogwheels inside the mount have been replaced with belts. This makes the mount run smoother, and removes some of the backlash.

https://www.firstlightoptics.com/belt-mod-kits/rowan-astronomy-sky-watcher-eq6-neq6-neq6-pro-and-orion-atlas-eq-g-belt-mod-kit.html

The neq6 pro, without the belt modification, costs about £ 1100+. So 800 with the modification seems a fair price, if the modification is done by a qualified person, and the mount is in good condition.

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14 hours ago, Cosmic Geoff said:

It has a long focal length and a narrow field of view, which I'm told makes it difficult to use for imaging, compared with a small short focal length refractor. In practice, you could image small galaxies with it, while a lot of other things will fail to fit in the FOV.  If you have Stellarium and some camera specs you can see this for yourself by modeling what various things look like in the camera frame.

I have played around with deep space EEVA using a Startravel 102mm f5 refractor and a ASI120MC camera, neither of which I bought for this purpose.  Much easier to manage than using a f10 SCT.

Many thanks, I understand what you are saying and it makes sense. I could go down the fit a hyperlens + camera in place of the second reflector to get down to F2 but for the cost of that, I could buy a decent reflector and have the best of both worlds so doubt I will go that route ... Keith

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11 hours ago, wimvb said:

It means that the cogwheels inside the mount have been replaced with belts. This makes the mount run smoother, and removes some of the backlash.

https://www.firstlightoptics.com/belt-mod-kits/rowan-astronomy-sky-watcher-eq6-neq6-neq6-pro-and-orion-atlas-eq-g-belt-mod-kit.html

The neq6 pro, without the belt modification, costs about £ 1100+. So 800 with the modification seems a fair price, if the modification is done by a qualified person, and the mount is in good condition.

Thanks, Wim, now I know :) and another mystery solved ...Keith

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4 hours ago, G4EQZ said:

I could go down the fit a hyperlens + camera in place of the second reflector to get down to F2

That sounds a lot easier than it actually is. The faster a scope is (lower f-number), the more difficult it is to get collimation, critical distances, focus, squareness, etc etc, right. At f/2, everything is supercritical. Personally, I'd hesitate to go faster than about f/4, unless it's a camera lens.

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4 hours ago, wimvb said:

That sounds a lot easier than it actually is. The faster a scope is (lower f-number), the more difficult it is to get collimation, critical distances, focus, squareness, etc etc, right. At f/2, everything is supercritical. Personally, I'd hesitate to go faster than about f/4, unless it's a camera lens.

Thanks, Wim, Advice noted and understood - sounds like every approach has its challenges and as said before I need to learn to walk before I run ... Keith

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Well the second hand EQ mount had been sold so just bit the proverbial bullet and ordered the EQ6-R Pro which will be permanently mounted on a pier which is currently under construction. Hopefully, this will resolve some of my issues. Also looking at a Skywatcher Evostar 80ED DS-Pro  on fleabay.

Thanks for the advice guys, taken me from 2% to perhaps 5% expert so still a long way to go yet :)

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Posted (edited)
On 16/05/2019 at 21:30, G4EQZ said:

Well the second hand EQ mount had been sold so just bit the proverbial bullet and ordered the EQ6-R Pro which will be permanently mounted on a pier which is currently under construction. Hopefully, this will resolve some of my issues. Also looking at a Skywatcher Evostar 80ED DS-Pro  on fleabay.

Thanks for the advice guys, taken me from 2% to perhaps 5% expert so still a long way to go yet :)

 extra 0,5% :): The best thing you can do without building something to cover the mount (and scope) is to buy a telegizmo 365 all weather cover
http://www.telegizmos.com/365 sizes and prices page 2.htm

They are the best covers you can buy.

Edited by Waldemar

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