Bit of play near focuser on Lunt LS50THa

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04Stefan07
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Bit of play near focuser on Lunt LS50THa

Post by 04Stefan07 » Sun Jan 24, 2016 1:19 am

I have noticed since I got my Lunt a while ago there is a bit of play between the focuser and tube. Check out in the photo below where the arrow is pointing to.

It moves very slight which causes everything attached up to the blocking filter to move.

Not sure if they are all like that. Also when I used the Lunt for the first time in a while last week as I was focusing it was making a kind of a sticky noise (only way to describe it!) Maybe because I hadn't used it in a while?

Does anyone have a similar issue?
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SOLAR SCOPE: Lunt LS50THa Pressure Tuned including B600 filter
MOUNT: Skywatcher HEQ5 Pro
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Re: Bit of play near focuser on Lunt LS50THa

Post by Brendan » Sun Jan 24, 2016 2:03 pm

Hi Stefan, my Lunt 50 has that play, I can't say I've noticed any detrimental effect.
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Re: Bit of play near focuser on Lunt LS50THa

Post by marktownley » Sun Jan 24, 2016 4:33 pm

If you're saying the play is in the threads of the helical focuser and the interface of the threads of the red pressure tuned section then that is a easy fix. Use some plumbers (PTFE) tape, unscrew the focuser, wrap the focuser threads with tape (exact amount will depend on how much play), screw it all back together and trim off any excess unsightly tape. This method works well with the PST etalon assembly too which suffers from play in the threads too.
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Re: Bit of play near focuser on Lunt LS50THa

Post by 04Stefan07 » Sun Jan 24, 2016 10:26 pm

@Brendan
Looks like it might be a common issue or part of the design with these scopes. Yeah there isn't any serious effects at all. If you centre the Sun in the eyepiece and then push the BF then the Sun will not be centred. Not a huge issue at all because you can easily re-centre it.

@marktownley
Sounds like a good fix Mark. Will need to have a look.
SOLAR SCOPE: Lunt LS50THa Pressure Tuned including B600 filter
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Re: Bit of play near focuser on Lunt LS50THa

Post by Lowjiber » Tue Jan 26, 2016 2:47 pm

Stephan, the helical focuser on the Lunt 50 is a design and manufacturing nightmare. The "sticky noise" you heard is caused by one, or both, of the following:

1. The small Philips screw that can be seen when you run the focuser all the way out, is scraping against the outer tube. This will be evident by metal shavings in and around the screw. Within two hours of operation of my new Lunt 50, I had Lunt replace the focuser two times. On the last one I received from Lunt, that screw literally fell out when I backed the focuser out.

2. The two focuser tubes are not concentric, the difference in the two eventually causes so much wear that metal shavings begin to appear when focusing.

I finally (after three focusers) called Scott at Starizona to purchase a Borg helical focuser and the adapter that Starizona makes for the Lunt 50.

Note: Because Starizona is a Lunt dealer, you won't find either the Borg focuser or the adapter on their website. You need to call Scott. He's very aware of the problems associated with the OEM focuser and will hook you up. :D
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Re: Bit of play near focuser on Lunt LS50THa

Post by GuillermoBarrancos » Tue Jan 26, 2016 6:23 pm

I am highly disappointed in Lunt reading about these issues. First there were the manufacturing issues, with people having to wait 6 months or longer for their delivery.... and now this.

I know they try to press the prices down and compete with the Quark in price, but I think people rather pay 50 to 100 bucks extra for a normal functioning focuser, instead of this helical nonsense.

I was jumping of joy (almost literally) when they announced the Lunt 50 and wanted to order one, but the moment I discovered it came with a helical focuser, it was an instant anti-climax and I went for the Quark chromosphere instead.

And now a year later I can´t say I regret my decision to be honest.

It´s crazy you were pretty much forced to fork out more cash to buy the borg helical focuser (which ain´t cheap) to get a proper functioning scope and as I see you have the B600 filter option.... you basically ended up in the price range of a Lunt 60t with normal focuser.

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Re: Bit of play near focuser on Lunt LS50THa

Post by 04Stefan07 » Thu Jan 28, 2016 3:04 am

That isn't comforting knowing that the screws might be scraping and creating metal shavings!

I will check out my scope tonight.
SOLAR SCOPE: Lunt LS50THa Pressure Tuned including B600 filter
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Re: Bit of play near focuser on Lunt LS50THa

Post by 04Stefan07 » Mon Feb 01, 2016 7:50 am

Scope looks ok but there is that bit of play when I am focusing.

Can get annoying at times.
SOLAR SCOPE: Lunt LS50THa Pressure Tuned including B600 filter
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Re: Bit of play near focuser on Lunt LS50THa

Post by nickatnight » Tue Feb 16, 2016 1:35 am

Tightening that little screw fixed the play on mine. I believe my screw loosened as I kept trying to adjust focus with the focus lock screw tightened. Do this enough and the screw works its way loose. I've pretty much trained myself not to try and rack the focus with that focus locking screw tightened. Just forget sometimes when my head is buried under a hood. It's been a few months without a need to tighten it as I've been careful.

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Re: Bit of play near focuser on Lunt LS50THa

Post by 04Stefan07 » Fri Sep 29, 2017 12:47 am

Just reviving an old thread!

I think a company in the UK or US has made I think a cray style focuser for this Lunt?
SOLAR SCOPE: Lunt LS50THa Pressure Tuned including B600 filter
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Re: Bit of play near focuser on Lunt LS50THa

Post by marktownley » Fri Sep 29, 2017 9:33 am

Both Moonlite and Starlight offer retro fittable quality focusers for this scope.
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Re: Bit of play near focuser on Lunt LS50THa

Post by Live_Steam_Mad » Thu Jan 18, 2018 4:05 pm

Yep, my LS50 has the same annoying play in the same place, where the helical focuser meets the Etalon body. My serial no. is 20158xx.
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