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Upgrading the focuser on a Heritage 130 flextube dob-ette


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My lady friend recently gave me one of these sweet little Dobs, about a month ago, to use as a pick-up-and-go scope. It's a super little instrument, ideal for the job, but I do have one quarrel with it.

I hate the plastic screw-in, screw-out focuser.

Has anyone tried upgrading the focuser? Can it be done (reasonably elegantly, I mean, and at a reasonable cost)?

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That's what I thought too, James.

It's just that the Heritage 130 is such a sweet little machine! But it would be perfecter (if you'll pardon such abuse of the English language) with a slightly better focuser!

I was just hoping that someone had looked on it with the same slightly jaundiced eyes that I have, and had come up with a solution!

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I emailed FLO about this. The Heritage really isn't up to being upgraded, and doesn't in fact have a replacement focuser. Besides, £200+ is a lot for a focuser for a £130 scope, money would be better spent upgrading the scope to something with a Dual-Speed Focuser built in ;). (Of course that isn't a problem for you, but might be for other Heritage users ;))

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Plumber's PTFE tape wound round the threads make it feel better, keeping it there is another matter. :grin:

Wait until you see an Explorer 130 at a Star Party and ........................... :evil:

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Funnily enough I'd thought of just that focuser Shane, having seen that you used it on the suitcase dob :)

My gut feeling is that because the 130 flextube has just an upper ring rather than cage and it's really quite lightweight, fitting an aluminium focuser on might well twist the ring and make it very difficult to align the focuser and secondary. I think it would need additional support, but how that might be achieved without compromising the design to the point where the scope wouldn't close up is hard to see. It might be easier just to build an entirely new upper cage, assuming the trusses are strong enough to carry it.

James

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I think you are possibly right James, although looking at the design, as long as you attached a plate for this 2" focuser on top of the existing plate it might work depending on how strong the upper cage is. I tend to agree though that it might be better to try and improve the existing focuser first.

Skywatcher_Heritage_130P.jpg

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If you just had a 1.25" to 2" adapter, wouldn't the FOV be the same as the 1.25" Barrel limit?

I've had a look at the focuser, and really can't see how it can take anything slightly heavier, it would knock the scope out of balance.

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That or sell it, buy a solid tube 130P and put it on a home-made dob base. By the time you've done that though it's probably cheaper to sell it and buy a solid tube 150P already on a dob base...

James

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<<I think it's more the smoothness the OP is looking to improve, not necessarily the field?>>

Yes, Moonshane, that's more or less where I am. I'm content that the focuser only takes 1.25" eyepieces, but I don't like the amount of play in it, especially when the eyepiece has to be screwed out far enough to cope with my short sight. Also, I wish it had rack & pinion adjustment instead of helical. I find it disconcerting that the eyepiece rotates when I adjust the focus, and if I put my little webcam in there it plays havoc with the usb wire!

I do realise it would be silly to try and attach an Antares Dual Speed Crayford Focuser or something like that. I just wondered if anyone had tried any DIY improvements that might make me feel happier with the existing setup.

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I agree about it being un-nerving having the eyepiece rotate (I move my eye away), but I often don't need to adjust it too much, but then I don't have that much to correct... if only they came with a better focuser to begin with, oh well..

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Ooh. I was dead excited when I saw this thread title & thought it night be a how-to guide. All the same, I'm glad to see i'm not the only one who has issues with the Heritage's focuser. :)

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I think it's more the smoothness the OP is looking to improve, not necessarily the field?

If that is the case then i found a way to make the focusing more smooth. Its very hi-tech, so pay attention:

Turn the focusing mechanism both ways over and over and over and over to strip any paint from the threads. Be sure to cover the secondary mirror while doing so and tilt the scope downwards so no flakes drop onto the primary. Also adding a couple of drops of oil will help also.

The focuser on this scope is the only negative i found with it.

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I'm still tempted by the idea of fitting an inexpensive rack+pinion 1.25" focuser in place of the fitted helical one. You've prompted me to look around, and it does seem there are suitable focusers available without spending too much money.

But I'm put off by

the fiddly job of hacking off the existing focuser while leaving a decent base-plate to put the new focuser on;

[ii] the chance that the new focuser might not be able to focus at the scope's natural focus point;

[iii] the thought that if I leave my Heritage 130 Dob strictly alone, I could sell it for a decent price and perhaps put the proceeds towards a Skymax. Except that the Skymax also appears to have a helical focuser (I may be wrong here). So maybe a 150p Dob instead. Much less portable, but looking more like a proper scope.

There is also the little matter that my Heritage 130 was a present from my lady friend, only a month or so ago. So (at least for now) I have to be utterly delighted with it. And I have to admit that, apart from this niggle about the focuser, I am!

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Learn to love your Heritage. It really is a great scope. It really will serve you well.

Ok so the focuser is not brilliant but when you get used to its way of working, you will not notice it as a problem.

As i said, the only niggle i found with it, is the focuser but i am comfortable with it now and the scope does give great views.

I dont think there is such a thing as "The Perfect Scope". Every scope will have something about it that we dont like.

At least with the Heritage, the only negative thing with it has no real detremental effect on how the optics perform.

I dont use my Heritage much now since i bought an 8se, but its a keeper.

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I agree that the focusser movement is a bit rough and wobbly - but hey, so am I. :laugh:

In truth, I can't think of another scope in the same price range that would give me the freedom that this one does, so I've just decided to live with it.

My only regret is that I had to buy mine :wink:

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