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Lunt 60 mm double stacked solar scope blocking filter issue

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#1 SAP Astro

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Posted 16 April 2016 - 09:26 AM

Hello,

 

I have a Lunt LS60THA double stacked pressure tuned solar scope. A few days back, I noticed that it was impossible to focus the scope, no matter what I did. Further investigation revealed that the eyepiece end of the B1200 blocking filter has almost turned opaque. A picture showing it is attached herewith. I have no clue what this is. The part is not damaged, it did not fall. Cleaning it from above has no effect. It clearly looks something like fungus. Is there any way I can clean it? Has anyone of you ever faced such a problem? If yes, what is a solution? I am from India, so sending it back to Lunt is not an immediate solution for me. Moreover, I wanted to use this scope for the Mercury transit. I would appreciate any help from anyone.

 

Thanks in advance!

 

Clear skies!

 

Shekhar

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#2 junomike

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Posted 16 April 2016 - 10:04 AM

Looks like Rust Deposits to me.

Best to find out before using it again.

 

Mike



#3 SAP Astro

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Posted 19 April 2016 - 07:22 AM

Thanks, Mike! I have contacted Lunt and requested them for a replacement. Yet to receive a reply from them.

 

Shekhar



#4 junomike

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Posted 19 April 2016 - 01:36 PM

Be sure to update the outcome.

 

Mike



#5 Bill Lee

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Posted 20 April 2016 - 04:31 AM

I, too, just found this problem. I'll be contacting Lunt today since it's covered under warranty.



#6 garret

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Posted 20 April 2016 - 12:28 PM

Has anyone of you ever faced such a problem? If yes, what is a solution?

 

I had the same problem, its a design flaw of the IR/  Energy Rejection Filter, I changed the filter by myself with an adapted IR filter from Astromik, but you must get a new ir filter for free from Lunt because they do know the problem exist for many years now.

 

Garret van der Veen


Edited by garret, 20 April 2016 - 12:30 PM.

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#7 Bill Lee

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Posted 20 April 2016 - 02:16 PM

 

Has anyone of you ever faced such a problem? If yes, what is a solution?

 

I had the same problem, its a design flaw of the IR/  Energy Rejection Filter, I changed the filter by myself with an adapted IR filter from Astromik, but you must get a new ir filter for free from Lunt because they do know the problem exist for many years now.

 

Garret van der Veen

 

 

Yes. I just called them and they're sending out a free replacement ITF and instructions on how to change it. It was very smooth and quick.


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#8 Scott Rose

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Posted 24 April 2016 - 05:20 PM

I had the same problem also.   



#9 davidmcgo

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Posted 03 May 2016 - 12:14 AM

Me too, got my LS60THa BF1200 back in 2011, been great up until checking this past weekend.  Mine isn't into the main light path yet but the two semicircles were not there a month ago.  Scope is stored inside so not temperature cycling every day.

 

Dave

 

 

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#10 orion61

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Posted 03 May 2016 - 04:08 AM

OUCH!! Been wanting one, now I have a couple very important questions to ask.. Filter DETAILS PLEASE???



#11 davidmcgo

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Posted 03 May 2016 - 06:32 PM

It is the ITF filter at the input side of the BF1200 diagonal.  Lunt said they'll send me a new one to pop in.

 

When I have the old one out, I'll grab measurements and see if the Maier Photonics filter DAVIDG posted about a while back is a drop in size or not.

 

Here's that thread:

 

http://www.cloudynig...-alpha-filters/

 

Dave



#12 davidmcgo

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Posted 07 May 2016 - 11:58 AM

My replacement BG filter made it here but the email with instructions to replace it didn't.  I assume it is as simple as it looks, remove the retainer, swap filters, and re install.  Can anyone with a Lunt BF who has done this please confirm?  

 

I am also going to see if I can clean the old one, either with Meguire's acrylic polish or with CLR as I have seen mentioned.  Thanks!

 

Dave



#13 davidmcgo

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Posted 07 May 2016 - 03:20 PM

Just swapped mine out successfully.  The glass element is 0.785" diameter and 0.1" thick.  There was a little black RTV that was holding the retainer threads but it scraped off with a toothpick.

 

I tried soaking the old BG filter in a cap of CLR and then rinsing which cleaned up the bulk of it but there are two etched areas right about where the retainer sits that are still there.  I tried a bit of Meguire's PlastX polish but that did not clear them off.

 

Note, the size is bigger diameter than the Maier Photonics ITF and a little thinner.  I had seen those discussed as fitting the Lunt in addition to the PSTs but that appears not to be true, at least for my BF1200.

 

Dave


Edited by davidmcgo, 07 May 2016 - 03:24 PM.


#14 BlueGrass

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Posted 08 May 2016 - 10:11 AM

Just curious, what are the ages and sky times of these filters before they need to be replaced?



#15 davidmcgo

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Posted 08 May 2016 - 10:52 AM

Mine was coming up on 5 years with infrequent use.  From reading up, it is likely more related to humidity.

 

The individual BG38 filter can't be very expensive but I'm not finding a source for one off in the size Lunt uses has been difficult so hopefully Lunt will offer replacements even after warranty for nominal cost.

 

 Newport Glass lists a 1" diameter for around $45, but the BF1200 diagonal uses a smaller 0.785" with a machined recess to fit.  The 1" would fit but need some additional retainer to keep it centered which wouldn't be hard to make.

 

Dave



#16 BlueGrass

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Posted 08 May 2016 - 12:52 PM

Ah .. thanks for the info Dave. My 60 was just purchased earlier this year and I had a thought based on the various posts, that it might be moisture related. Maybe putting some desiccant pouches around the diagonal would help reduce this?



#17 davidmcgo

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Posted 09 May 2016 - 11:11 AM

After getting the replacement in and having some time to kill since clouds just came in after being clear initially blocking my view of the transit of Mercury, I decided to see if what more I could do with the original blue glass filter.

 

I got pretty aggressive with the PlastiX Polish, doing targeted heavy polishing with a Q Tip and letting it dry then polishing hard until I heard squeaking.  A number of goes that way followed by a good polish on both sides cleared it up nicely, and I don't see any sleaks with a loupe.

 

I think the initial CLR did a lot but the plastic polish with aggressive pressure and a cotton swab worked very well.  Using the polish with soft lens tissue did no where near as well.

 

So I put the polished original wrapped in lens tissue in a small ziplock with a desiccant pack to keep as a spare.

 

Dave


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#18 Bowmoreman

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Posted 07 July 2017 - 08:57 PM

Just found this thread. I have a 2010 vintage 60... Found the cataract yesterday...  I took it apart this AM, and soaked it in vinegar rigor to cleaning with a Q tip...  Was much better but NOT good enough. Emailed Lunt today and got a quick reply from Ms. Lunt. I will be heRing the plan shortly

 

pretty small and insignificant part. Should be a non big deal... Stay tuned

 

Dave



#19 Bowmoreman

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Posted 08 July 2017 - 09:30 AM

Quick update: the vinegar cleaned ITF has at least made me able to find and center and (sorta) focus on the Sun! So it's better... but not good enough.

 

(I use my Denkmeir Binoviewer with Power x Switch with Panoptic 24's)

 

I hope to hear back from Lunt on Monday and that the answer is they still just send you a new blue ITF filter...

 

stay tuned...



#20 Bowmoreman

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Posted 17 July 2017 - 02:19 PM

Just to update one/all:

 

I heard back from Lunt (Jennifer Lunt), and they sent me an all new ITF... No charge, even though the scope is 7 years old and I'm not the original owner!

I put it in, and... shazzzaaaam....

back in business double stacked... saw the current large sunspot and a nice large prom...

 

Great support from a great company


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#21 Matthew Ota

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Posted 20 July 2017 - 09:45 AM

I live in the Los Angeles basin. It is mostly a dry climate. We get monsoonal moisture in the spring and humidity can climb. It seems to me that a good practice would be to use dessicant packages in your solar telescope case to absorb moisture to previent this type of oxidation.



#22 Bowmoreman

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Posted 21 July 2017 - 10:20 PM

I live in the Los Angeles basin. It is mostly a dry climate. We get monsoonal moisture in the spring and humidity can climb. It seems to me that a good practice would be to use dessicant packages in your solar telescope case to absorb moisture to previent this type of oxidation.

I did.. In the case closed up snug when not in use... That said it lives in my observatory, which does get up above 100f in summer and below -20f in winter



#23 BinoGuy

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Posted 22 July 2017 - 03:20 PM

Honest question here.  So (and I do realize I've been commenting a LOT today, cloudy skies and rain this weekend) I sort of see a pattern with Lunt; gunk in their PT etalons, poorly matched internal lenses, possibly. Missing o-rings, and now this darkening thingy.  I like the pictures I've been seeing from Lunts, and there seem to be issues with the DayStar EPs, so am I looking at the higher-end Coronados only?



#24 rockethead26

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Posted 22 July 2017 - 07:36 PM

As a counterpoint, I've had my Lunt 60 Pressure Tuned BF1200 for about 5 or 6 years and have experienced none of the issues mentioned. I would buy another in a heartbeat.


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#25 Bowmoreman

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Posted 22 July 2017 - 10:11 PM

their support is perfect.. Nuff said


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