Scope improvements

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Scope improvements

Postby brian jones » Sat Mar 06, 2010 8:46 pm

I recently purchased a second-hand Helios 120mm f8 refractor on an EQ3-2 mount.I'm happy with the scope so far, but i'm an inverterate fiddler and always looking to improve stuff, and have a number of questions.

1) I've noticed that although this scope is fitted with a 1.25in diagonal and eyepieces, if i remove the diagonal the focus tube has a 2in diameter. Will this scope take 2in accessories, and will I gain anything (apart from a larger overdraft) by using 2in eyepieces?

2) At greater magnifications, I get a fair amount of wobble. I tried placing 10Kg of weights in the accessory tray, but wobble is still there. Is there any way of stiffening the mount or should I consider a larger mount (maybe an EQ5)?, or would an electronic focuser help? (OTA weighs 4.4Kg)

3) I'm considering making a concrete or metal pier in the backyard to take the scope - What would be the maximum height for the pier before it becomes rediculously heavy/unfeasible to build? Would 5ft be too large?

4) You can get dual-axis motor drives for these mount. Are they accurate enough to follow objects at higher magnifications (around 150x)?

5) HONEST opinion of the scope - should I be looking for something else?.

My main usage would be for general astronomy; some dso, planetary, clusters etc... and maybe imaging later. I don't want to commit to a larger scope yet because i'm considering re-locating. Sorry if I'm asking a lot of questions, but understandably I would like a clear idea of what I might need before spending my hard-earned money.

Thanks for looking and any help you can give.
May your skies be unblighted by cloud. [:)]
brian jones
Posts: 45
Joined: Mon Feb 13, 2012 7:04 pm

RE: Scope improvements

Postby brianb » Sun Mar 07, 2010 12:23 am

1. Yes I believe it will take 2" accessories. Apart from a wider field at low powers, there is no advantage in doing so.

2. I do not think an EQ3-2 is adequate for a 5" refractor. I have a WO FLT 110 which is smaller, shorter and possibly lighter than your scope, and quite honestly an HEQ5 Pro struggles under it (my site is pretty windy though).

3. Planning permission required if height exceeds 2 metres, IIRC.

4. Moot, see 2.

5. You may find there is significant false colour on bright objects - a minus violet filter will help. Not bad for a first scope, apart from the mount which is inadequate. But a 5" frac is neither here nor there - not a light bucket and too big for "grab 'n' go". Should be good fun though, once properly mounted.
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Joined: Mon Feb 13, 2012 6:49 pm

RE: Scope improvements

Postby brian jones » Sun Mar 07, 2010 4:13 pm

Thanks for your feedback brianb, you've pretty much confirmed what I thought about the mount.

I may have been a little ambitious with a 5ft pier, but as an aside, if the pier was free-standing then planning permission is not needed.
brian jones
Posts: 45
Joined: Mon Feb 13, 2012 7:04 pm

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