Changing focuser on a Lunt LS60

[AWR]

Has anyone changed the focuser on a Lunt LS60?

I'm looking to change the focuser (it's a bit rubbish) and I've never done this before. I know I can buy a Feathertouch focuser to fit but I'm trying to see if either of the cheaper options (Baader / Moonlite) will fit. How do I remove the focuser? What do I measure?

Any help will be greatly appreciated.

Many thanks,

Andrew

[AWR]

If no-one has changed the focuser on a Lunt, I'd be really grateful if someone could give some general tips about changing focusers in general.

Thanks again,

Andrew

[ollypenrice]

I'm watching as well, Andrew. A Steeltrack would be great if available. Maybe we should just email TS and Baader.

Olly

[AWR]

I emailed Baader and their reply was "We don't know". Not exactly helpful. I haven't tried TS yet, I'll send them a message now.

Andrew

[AWR]

Olly:

I've had a reply from TS (nice and quick!). They're suggesting using the shorter Newtonian version of the Steeltrack.

I've sent another email asking a few clarifying questions - I'll post the details when I hear back.

Andrew

[Merlin66]

I have a guy in Finland who is looking seriously at "modding" the Lunt60. He has done a lot of measurements etc.

I'll ask him about the fixing arrangement of the focuser and whether or not he sees a problem.

Stay tuned....

[Stephen]

Don't Moonlite make custom flanges to order?

[Merlin66]

Hmmm

the focuser could end up costing more than the original telescope!!!

[AWR]

JMI make a base for their EV focusers to fit a Lunt LS60.

Are JMI any good?

Andrew

[RikM]

Do I take it, from the responses to this thread, that it would be better to get the one with the Feathertouch option from Ian King at the outset?

[A McEwan]

I've taken the standard focuser off a few times. Its attached using three small grubb screws and is very simple to take off and replace. Moonlite do indeed make a Lunt flange, which is tempting, but for me unnecessary as my standard gso works fine.

Ant

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[AWR]

Do I take it, from the responses to this thread, that it would be better to get the one with the Feathertouch option from Ian King at the outset?

I wish I had.

The supplied focuser is ok but only ok. It works well enough with my TS planetary EP but it did not like my TV Delos at all.

In the future I will use my scope for imaging and I would like something a bit more secure.

Hopefully I should have a few options priced up by the end of today.

Andrew

[AWR]

Moonlite do indeed make a Lunt flange, which is tempting, but for me unnecessary as my standard gso works fine.

Ant

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Where are they available from?

Andrew

[A McEwan]

Well I would presume FLO could arrange it, or any of the ither Moonlite dealers? Failing that yiu could contact Ron at Moonlite directly through their website www.focuser.com

Ant

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[Photonist]

Hi,

I’m responding to Ken’s private tip of this interesting topic.

Unfortunately, I don’t have a final solution, yet…

I have planned to replace the poor Lunt focuser from the beginning and probably will do it if my Lunt 60 telescope mod using the SW150/1200 mm turns out to be successful. Unfortunately no sunshine here since the first short test 3 weeks ago and not much hope next week either.

I have skipped the FeatherTouch model as too expensive compared to the Lunt 60 telescope price. So far I have not searched seriously for other options. As a first aid I installed a cheap Sky Watcher Motofocus which made the focuser more usable but bulky.

The Lunt focuser is attached to the telescope body with a dovetail and 3 recessed hex screws (4 mm diameter) very near the edge. The dovetail front diameter is 78mm and its length 6 mm

The Lunt body takes a 78 mm diameter focuser so it is perhaps not a common standard. The Lunt focuser body length without the dovetail is 52.3 mm plus the 2” adapter 14 mm and has a 34 mm travel.

Many refractor focusers have a long focusing tube protruding far inside the telescope body. The Lunt body can take only 33 mm because of the etalon module. The Steeltrack refractor model may have a too long focusing tube (looking only on the image). The Steeltrack Newtonian version is very nice and short and even has a dovetail, if only the dovetail diameter would match, but I haven’t found any measurements for it.

First I would research the Steeltrack Newtonian dimensions and then consider the much cheaper TS TSFOCR2M for 148 EUR. However, the TS diameter is only 72 mm, so a simple 3 mm spacer ring would be needed. I use the TS SCT version (158 EUR) in my PST mod and it works great.

Best wishes,

Viljo

[AWR]

Thanks Viljo,

I have found a few alternatives:

1. Baader Steeltrack:
   
   1. 
      
   2. The Newtonian version is available with the 78mm dovetail. It's a bit shorter overall but the length of the tube on the blocking filter can compensate. The drawtube only has a 30mm range:- Baader Steeltrack Okularauszug für GSO, TS, ICS, Meade Newton Teleskope
      
   3. The refractor version will require an adapter which TS can supply (70-90 Euro) but this allows a longer drawtube.
      
      
   4. TS Monorail: This is a much more similar size focuser:- MONORAIL 2' Newton Auszug - genauer und belastbarer
      
   5. Moonlite: There is a Lunt adapter but it is not on their website yet. They suggest using the CS (SCT) version with a 1.5" drawtube.
      
   6. JMI: There is a Lunt adapter for the JMI EV range of focusers.
      
   7. Feathertouch as we know.
      
      
      For options 3,4 and 5 I am waiting for prices and I will update as they come in.
      Andrew

[AWR]

Well I would presume FLO could arrange it, or any of the ither Moonlite dealers? Failing that yiu could contact Ron at Moonlite directly through their website www.focuser.com

Ant

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Thanks Ant, (should have said that earlier).

[Photonist]

Andrew,

Yes, I also noticed the Steeltrack dovetail diameter in the “Recommended accessories” section the “Base for Newtonian focusers for tubes with…” where they say “Diameter of the central hole ... 78mm. Fits for all telescope focusers with a male dovetail with that diameter. The focuser is held in place with two slug screws from the side.”

That would seem to fit the Lunt body exactly (if the Steeltrack dovetail is long enough, that is 6 mm).

I’m afraid the Steeltrack refractor version is too long and the drawtube protrudes too far into the telescope.

The TS Monorail is also interesting, but it may be a bit long (70 mm) when using a focal reducer. I think there was just enough infocus using a 0.5x FR with the Lunt focuser.

Viljo

[AWR]

It was a Michael from TS who tipped me off about the Newtonian Steeltrack fitting straight onto the Lunt body.

Moonlite do a version of their CS focuser where the focal reducer is fitted inside the focuser. I don't know if that would be useful.

Andrew

[Zakalwe]

Sorry to bump an old thread, Andrew, but did you get this sorted? The focuser on my Lunt really is poor, with the drawtube moving when the focus lock is tightened.

[JamieW]

I'd also like to know how you got on. The focuser lets down an otherwise excellent piece of kit.

[Zakalwe]

I've been in touch with michael @TS. He advises that the TS Monorail needs and adapter, but the Baader short ocuser for Newtonians fits straight on. I;ve ordered one from Bern @ Modern Astronomy, which should be here in a few days or so. I'll post up my findings once it has landed.

[AWR]

Sorry to bump an old thread, Andrew, but did you get this sorted? The focuser on my Lunt really is poor, with the drawtube moving when the focus lock is tightened.

Sorry to take so long to get back to you - I've been away for some time.

I went for a Moonlite in the end - have a look at this thread.

Andrew

[Zakalwe]

Thanks for replying. I ended up with a Steeltrack.