Lunt 60 Pressure tuning question(s)

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pauljones
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Lunt 60 Pressure tuning question(s)

Post by pauljones » Tue Nov 26, 2013 2:01 pm

I've been out three times now with my new Lunt 60, pressure tuner model. The first time was amazing. Great detail, easy operation, everything you could ask for. In short order, I had tuned the instrument such that abundant detail was visible on the disk.

The next two times have been disappointing. The second time, I had a lot of trouble getting detail to pop out and the third time I actually couldn't, visually. I could focus - the disk edge and sunspots were focused softly but focused. But no matter what I did with the tuner knob, no H-a detail emerged. I released the pressure and re-tightened. I wound back and forth slowly. Nothing. However, hooking up a camera and lowering gamma, I could get some detail to emerge, though it was far from a pleasing image.


My questions:

1) How large an effect will seeing have on this? More in a moment.

2) How large an effect will temperature have? PV = nRT, after all.

3) How important is temperature equilibration?

4) Should the pressure be released after each observing session? The manual says no but manuals often don't have the best practices, in my opinion.


Now, my sense is that I have nothing to worry about. In my last session, the seeing was atrocious and, I assume, that explains the difficulty in tuning (and focusing...or really seeing much of anything). I also assume significant changes may need to be made on the tuner with large differences in temperature.

But I'm coming up on 30 days and just wonder if it the scope is behaving as expected. I sort of think yes, but the little paranoid gland deep in my brain begs me to ask.

Is it possible that the seeing can be bad enough to render H-a detail invisible in a properly functioning scope?

Thanks.

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Re: Lunt 60 Pressure tuning question(s)

Post by robert » Tue Nov 26, 2013 4:31 pm


My questions:
1) How large an effect will seeing have on this? More in a moment.
Massive effect
2) How large an effect will temperature have? PV = nRT, after all.
Very little
3) How important is temperature equilibration?
Not important
4) Should the pressure be released after each observing session? The manual says no but manuals often don't have the best practices, in my opinion.
Makes no difference


My answers to your questions from my experience with a Lunt 60 PT.

Robert
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Re: Lunt 60 Pressure tuning question(s)

Post by swisswalter » Tue Nov 26, 2013 4:50 pm

Hi Paul

my experience is a little bit different:

My questions:

1) How large an effect will seeing have on this? More in a moment.
a lot but not as baad that you can't see Ha details

2) How large an effect will temperature have? PV = nRT, after all.
not very much

3) How important is temperature equilibration?
important, you can watch the improvement

4) Should the pressure be released after each observing session? The manual says no but manuals often don't have the best practices, in my opinion.

yes , it should be released before each new session
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

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Re: Lunt 60 Pressure tuning question(s)

Post by Robin » Tue Nov 26, 2013 8:28 pm

I don't think that these pressure tuners are the be all and end all of tuning ,not as easy as they are made out to be, I have a problem in obtaining an even illumination over the frame, it is always overexposed at some part of the frame view. The seeing has to be also very good to get any reasonable results, maybe I am asking too much of the equipment or aiming too high
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Re: Lunt 60 Pressure tuning question(s)

Post by pauljones » Sat Nov 30, 2013 4:22 am

Thanks for your thoughts and comments.

It had to have been the seeing as I had a very nice outing today and yesterday. I am still getting used to the PT, but I could see a lot of detail these last two days.

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Re: Lunt 60 Pressure tuning question(s)

Post by Derek Klepp » Sat Nov 30, 2013 6:31 am

I hardly touch my PT at all just my two bobs worth.

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Re: Lunt 60 Pressure tuning question(s)

Post by mattwastell » Sat Nov 30, 2013 10:02 am

Hi Paul
You seem to have many of your questions answered.
Seeing is king. I have had no issues with temperature variations at all. I PT once every 4th or 5th session.
Enjoy!
Matt Wastell



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Re: Lunt 60 Pressure tuning question(s)

Post by mwirths » Sat Jan 11, 2014 6:45 pm

Paul,

I just recently got a new Lunt 152. The first time I used it I like you saw abundant Ha detail (after taking the tuner off the equalize pressure and then turn it in to tune in the Ha band) But each subsequent time I could not tune it in at all, even in good seeing!

After talking to Rikki and Alan at Lunt a few times they felt that probably the O-rings in the tuner were not holding pressure any longer. Perhaps that has happened to you too? Replacing the O-rings is an easy fix.

take care

Mike

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Re: Lunt 60 Pressure tuning question(s)

Post by MapleRidge » Sun Jan 12, 2014 12:06 am

Paul...

If you manage to get the PT tuned and there is a leak in the PT, it will drift off band...speed will depend up how bad the leak is.

If you tune it and leave it for some time and the tuning appears to have changed slow turn the PT cap to compress and see if it returns to where you had it set before...if this fixed the view then a leak is pretty much the cause.

If adjusting the focus makes the difference you may be fighting the seeing...focus looks good, but suddenly the seeing changes (to the better or worse) and you wind up changing focus.

My DSII unit for the LS80 developed a leak inside the body, so it is currently at Lunt being serviced. If would leak off in less than a minute...so quite obvious.

Hope you get yours up and running they way it should.

Brian
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Re: Lunt 60 Pressure tuning question(s)

Post by pauljones » Wed Jan 15, 2014 2:23 pm

Thanks all. I see I haven't commented since the earlier comments and meant to. Things aren't as bad as it seemed when I first posted. I had a day of truly horrific seeing to the point I couldn't really see anything. I've since had better seeing and am relatively happy.

However, I think there is a chance that I'm seeing leak type behavior described by Mike. I'm going to test this more specifically next chance (perhaps this weekend). I'd be relieved if it was as simple a fix as swapping O-rings. I'd be more relieved if it just isn't doing it. :)

But the scope provides a good image in good seeing. Now I'm thinking of double stacking. When will it end?

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Re: Lunt 60 Pressure tuning question(s)

Post by swisswalter » Wed Jan 15, 2014 6:39 pm

Hi Paul

there is no end to the story ;-)


First get good results with the existing gear, then move on. One step after the other, it saves you money
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)

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Re: Lunt 60 Pressure tuning question(s)

Post by pauljones » Wed Jan 15, 2014 7:34 pm

I think it works fine in single-stack mode. I really do think the problem I encountered, which prompted my original post, was really bad seeing. I've had a number of good days since. And before. I want to test the leak possibility as I never do quite find the ideal tuning but I think that is still a matter of inexperience. However, I didn't even know it was possible so I simply want to check.

Anyway, enough about equipment. Here is the sun. This was shot about a week before the original post. So, the scope works fine when the conditions are good.



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Re: Lunt 60 Pressure tuning question(s)

Post by marktownley » Wed Jan 15, 2014 8:39 pm

looks good!
Image
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Re: Lunt 60 Pressure tuning question(s)

Post by swisswalter » Thu Jan 16, 2014 5:15 am

Hi Paul

indeed a fine mosaic. Maybe there is a gost at 5 o'clock
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)

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Re: Lunt 60 Pressure tuning question(s)

Post by Astrodan » Thu Feb 27, 2014 5:44 am

My LS60 would drift of tune .I believe the pressure leaked out the large threads on the tuner. I wraped the thread with gas pipe (White tape) and the Scope has been perfect .Clear Sky's Dan

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Re: Lunt 60 Pressure tuning question(s)

Post by solarchat » Thu Feb 27, 2014 10:27 am

Hey Dan,

Rikki will send you a set of free replacement rings if you ask.
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Re: Lunt 60 Pressure tuning question(s)

Post by sunshine » Sun Jul 06, 2014 2:17 pm

An answer for pauljones question 4.

I bought a Lunt LS60THa Pressure Tuned scope last month and the manual that came with it should be up to date .
I don't know if the manual is a Lunt production or produced by the European Distributor.
It has the name of Lunt-Solar-Systems- Exclusive European Distributors, Optus GmbH, Germany.
It is only two sheets of A4 .
A line on page three, in the second paragraph, Tuning reads........


" When not in use we recommend that you release the pressure by simply backing off the black handle from the cylinder body."



I think it makes sense to take the strain off the seals when not in use.
Long term trapped wind is no good for people or telescopes. ;)

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Re: Lunt 60 Pressure tuning question(s)

Post by swisswalter » Sun Jul 06, 2014 9:06 pm

Hi sunshine and Paul

I had never a problem letting the etalon under pressure
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE :)

from 7 am - 7 pm http://www.nanosys.ch

from 7.01 pm - 6.59 am http://www.wastronomiko.com some times vice versa ;)

sunshine

Re: Lunt 60 Pressure tuning question(s)

Post by sunshine » Wed Jul 09, 2014 1:35 pm

I thought I would have a look at the American and European Lunt Websites for their recommendations about releasing the pressure.
At least one of the sites had links to the manuals about a month ago.
Unfortunately it looks as though they have withdrawn or omitted the links.
It would have been nice to have had the official line from those in the know.

Cheers all.

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Re: Lunt 60 Pressure tuning question(s)

Post by solarchat » Wed Jul 09, 2014 1:52 pm

I don't work for Lunt but I release and depressurize the cylinder every time I set it up and I store the scopes with the cylinder in whatever position I was using it in.
The maximum change is only 3 psi from minimum to maximum so I don't think there is any danger of damaging seals by leaving it pressurized.

I own every scope Lunt makes except the 230mm and I have never had a cylinder go bad.
Stephen W. Ramsden
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Re: Lunt 60 Pressure tuning question(s)

Post by Bill Edelen » Thu Jul 10, 2014 3:32 pm

I almost never repressueise. I only do this if my adjustment range changes.Ricci said this is ok.I once had to store my sope for 4 months and when I took it out of case it needed no tuning adjustments. ...just my 2¢

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Re: Lunt 60 Pressure tuning question(s)

Post by _Zakalwe » Thu Jul 10, 2014 6:30 pm

Personally I always wind out the tuner when I pack it away. No reason or science.
I've also smeared a wee dab of silicon grease on the O-Rings (red rubber grease would work as well) as they were a bit dry leaving the factory. And a slight smar of lithium grease on the main regulator threads..the brass had a fair bit of "stiction" in it and this helped no end.

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Re: Lunt 60 Pressure tuning question(s)

Post by ForrestLockhart » Fri Jul 11, 2014 9:28 pm

I had problems such as you have had when my LS60 arrived.
I wasn't happy with the view through the scope. I griped and moaned until I finally dropped it off at Lunt in Tucson while on vacation. I don't know what Brian did in the 30 minutes he had the scope, but the effect was dramatic... I think. Some friends say it was always good, others agree that something good happened in Tucson.
The Head Nerd recommended that the tuner be backed off when not in use, so I do that.
Most folks don't think temps have an effect on seeing. My scope seems to work better if I leave it out in the Sun for a few minutes before observing. Any mechanical reason? Nope. It just seems to work better that way.
A dab of silicone grease seemed to make the tuner smoother. So I check that once in a while.
However, I would bet my old OIII filter that you have simply been a victim of bad thermal effects, i.e. bad seeing.
At 8:00 this morning the solar disk was a maze of detail, but by 11:00 I could hardly make out even moderate features that had been prominent earlier. If that view was the best the scope would do, I would have dumped it soon after I received it. But I think it was Mark and SwissWalter who told me to relax, learn the quirks of daytime observing and keep at it. I followed their sound advice. Glad I did.
By the way, nice image you did. Congrats.
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