Lunt Blocking Filter - Check yours, you won't regret it!

[AdeKing]

CLR is "Calcium Lime Remover" so basically limescale remover.

When I got my replacement, I used Viakal (Viakal Limescale Remover) on my cloudy filter and it came up a treat so I now have a spare.

 

[richard ashbee]

On 29/06/2018 at 10:31, alanjgreen said:

I am writing this post as I have just received and fitted a free replacement lens supplied by Lunt that has fixed my Blocking Filter and revolutionised my views...

 

The Story

I had begun to get a feeling whilst using my solar scope that it was getting more and more difficult to (1) get an initial view that I was happy with (2) almost impossible to increase magnification and get a sharp image (3) the sweet spot was shrinking  

I removed the Blocking filter and looked down the long extension tube to see a grimy looking front lens inside

I searched on the internet and found a picture of a new one and saw that the front lens was supposed to be clear. I set about cleaning it with Baader Wonder Fluid and the cleaning cloth which got rid of at least 80% of it, but a thin film remained (see pic).

After more internet searching, I found a post on cloudynights that showed the exact same problem being suffered by other folks and stated that Lunt were happy to send out free replacement lenses!

https://www.cloudynights.com/topic/534161-lunt-60-mm-double-stacked-solar-scope-blocking-filter-issue/

https://www.cloudynights.com/topic/433046-polishing-optical-acrylic-lens-element-in-a-lunt-s/

 

So, I took some photos of the scope, blocking filter and sales invoice and emailed Lunt USA on Monday this week.

On Tuesday (the next day!), Bresser Germany emailed me to say that Lunt had asked them to send me a free replacement lens (Great!)

The Lens arrived this morning (just 4 days after emailing Lunt!) and I fitted it into the Blocking filter following the supplied instructions, then headed out to view the sun...

Here is the glass as received...

Here are the supplied instructions...

Here is the blocking filter after I fitted the replacement glass (Looking very transparent) ...

WOW, WHAT A REVELATION!

(1) The image is so much brighter

(2) The sweet spot is so much bigger

(3) Higher magnification is no longer an issue and some lovely surface detail revealed itself ...  

I would encourage all Lunt Solar Scope owners to go check the front lens of their blocking filter for any signs of fungus or growth and if you find some then don't hesitate to email Lunt USA for a replacement.

Happy Solar Viewing,

Alan

Hi Alan was it under guarantee at the time, or how long had you had the scope before this happened? thanks

[alanjgreen]

2 hours ago, richard ashbee said:

Hi Alan was it under guarantee at the time, or how long had you had the scope before this happened? thanks

The scope was 5 years old in 2018.

[richard ashbee]

Thanks, good to know they still support you after the warranty

[anthony]

This thread was very useful.  After a few years in storage I very recently took my Lunt LS60T out and discovered it had this problem. Spent a whole day thinking it was just hazy cloud! Finally had a look and saw the issue.

My scope is 10 years old and I am the original owner. Lunt quickly put me contact with Brewer Germany and my replacement filter has just arrived - no cost to me. I am sure I saw one on the Lunt site for about $7.

I am very happy with this level of aftercare!!

 

Lunt were able to tell me that the blue glass is a UV Cut filter.

The newest version has a coating to inhibit this build up.

They also confirmed it was OK to try and clean the old BG filter and suggested CLR.

 

I used stuff lying around the house which didn’t do much so I polished it up with a soft wheel at low speed on the Dremel and whatever the red compound is that came with the Dremel. I’m not suggesting that anyone do this of course. I did it knowing that I could completely ruin it. 

I was careful not to scratch the glass!

Finished the process with a little bit of car polish.

Result was very effective, not perfect, but a massive difference. Had a few minutes with a decent view and ran off a few AVIs.

It’s been cloudy or I have been busy ever since!

[Merlin66]

Hmmm

I’m not sure I would be comfortable hitting an optical filter with a Dremel.

The CLR cleaning seems to work well.

I’m interested in the comment that the latest Lunt filter has a “protection coating”

I hadn’t hear that before.....need to follow up.

 

[anthony]

After the various cleaning agents had little effect the Dremel was the last resort as the bin was all it was good for otherwise. I was gentle, polishing rather than grinding.

[JeremyS]

Thanks for the OP, @alanjgreen, almost exactly two years ago. Every few months since, I have checked my filter. I recently noticed a hazy spot appearing, so contacted Bresser/Lunt and they sent me a new filter. Simple to replace and now up and running again 🙂

 

[PeterW]

Mine was fully gunked, took it out and then Quite aggressively  cleaned it so the scope was sort of useable, some umshiftable stuff round the edges. Contacted Lunt, then Lunt EU and got a spare filter and “pressure tuner o-ring and grease kit” in the post. (At 9yrs old I might as well, think the grease has worn away!). Very quick swap over, just not seen the sun since.. next week is looking promising. Great service.

PEter

 

[alanjgreen]

On 29/06/2018 at 11:31, alanjgreen said:

Here is the blocking filter after I fitted the replacement glass (Looking very transparent) ...

Happy Solar Viewing,

Alan

Here is an update to my blocking filter story…

After three years the replacement lens was starting to show signs of the original problem reoccurring… several small white patches could be seen on the edges and one central

A quick dip in “Cillit Bang Limescale and Shine” and the marks vanished.

After a good rinse under the cold tap and a quick final clean with Baader lens cleaner, it was as good as new.

I was out with the LS60 yesterday and the views were back to “normal” to my relief.

I am now ready for the show (as the Sun is finally awake!)

 

Alan

[Rusted]

My B1200S2 BF is already showing pale blue patches. Purchased from Bresser in March 2020.

My wife admits to having the right stuff in the hazardous chemicals cupboard.

Please expand on "a quick dip."  No rubbing?

There is a blob of black silicone sealant securing the filter holder.
Won't removing this void any guarantee?

[Merlin66]

A soak in CLR , a minute or so, followed by a rinse in cold water and a wipe to dry off.

This should give you some extended life.

 

 

[tooth_dr]

2 hours ago, Rusted said:

Won't removing this void any guarantee?

No it won’t. Lunt supply the glass and instructions to replace it, it’s not a modification.  I had to rub mine a bit to get all the marks off but didn’t do any harm. 

[PeterW]

I fair rubbed the life out of mine to remove the worst of it till the replacement arrived. Obviously the “Bang” works better, though probably when the “crud”‘isn’t quite as well developed as it was on mine. Im pretty sure it’s just just a polished bit of filter glass, so as long as you don’t scratch it you should be fine. 
 

Peter

[alanjgreen]

23 hours ago, Rusted said:

My B1200S2 BF is already showing pale blue patches. Purchased from Bresser in March 2020.

My wife admits to having the right stuff in the hazardous chemicals cupboard.

Please expand on "a quick dip."  No rubbing?

There is a blob of black silicone sealant securing the filter holder.
Won't removing this void any guarantee?

You need to remove the silicone to be able to unscrew the retaining ring. No it does not void the warranty as Lunt are happy to sell replacement blue lens on their website.

 

As for the cleaning, I added a small amount (enough to cover the lens) into a small plastic container, then put the lens into the solution for a soak. 
- I left it for half a minute then removed the lens and rinsed under the cold tap to remove the cleaner. 

Holding it up to the light I could see the marks were gone.
- If some marks remain give it another soak in the solution and repeat the rinse with water.

- if you feel like rubbing it, then a cotton wool ball dipped in solution should do the trick

Use Baader Wonder Fluid to rub the lens to a clean clear finish.

I wore disposable latex gloves during this whole process.

Alan

Edited July 3, 2021 by alanjgreen

[AdeKing]

I've just switched my filter out today, swapping it for the one I treated with Viakal 2 years or so ago.

Since I treated it 2 years ago the filter had been stored wrapped in tissue in a Ziploc bag with silica gel sachets as a spare and there was not a trace of cloudiness to be seen when I fitted it today.

In comparison, the one I received as a replacement from Bresser and fitted to the diagonal had gone really quite cloudy.

I think I might keep the whole B1200 diagonal in a bag with silica gel and see if that prolongs the life.

In the meantime, the cloudy filter was treated with Viakal, rinsed then polished with Baader Optical wonder fluid before being put into storage.

The view through the eyepiece has improved noticeably.

Ade

[Bernd Nies]

Just took my Lunt LS60T with B1200 out of the box and wondered about the low contrast. The front blocking filter is all fogged up. I bought it in 2017. 

They are currently at pre-order only: https://luntsolarsystems.com/product/blue-glass-for-lunt-blocking-filters/ for USD 8.75 plus USD 160 shipping costs ...

Edited June 13, 2022 by Bernd Nies

[Altocumulus]

I seem to have to replace mine yearly! Kept through the winter months in the cool and dry - don't know what else I  could do! 

[Bernd Nies]

44 minutes ago, Altocumulus said:

I seem to have to replace mine yearly! Kept through the winter months in the cool and dry - don't know what else I  could do! 

I had some polish left from polishing an acryl underwater camera dome port and could get the surfaces clean again. Maybe some low abrasive tooth paste with a low RDA value would do it as well.

[PeterW]

Just use an optical cleaning material without any abrasive, should get the middle looking better. I’d drop Lunt solar systems EU an email, I got a spare sent over for free even though mine was out of warranty. (If I remember correctly). I’m in the UK. Was a few years ago.

 

Peter

[Altocumulus]

Bresser Germany is usually kind enough to send spares out - does anyone understand why they fail and, obviously, there's no alternative. What exactly is its function - would we know if we didn't use the bg filter?

[Live_Steam_Mad]

2 hours ago, Altocumulus said:

Bresser Germany is usually kind enough to send spares out - does anyone understand why they fail and, obviously, there's no alternative. What exactly is its function - would we know if we didn't use the bg filter?

The BG38 Blue Glass filter is there to filter out the IR. I wouldn't recommend removing it, or else it would become a safety issue incase someone looked through it. They fail because BG38 gets "Glass Disease". No joke. Apparently.

Regards.

[Nigella Bryant]

I got mine free three years ago through bresser.  Mines been fine since putting new ones in exactly three years ago. 

[Altocumulus]

19 hours ago, PeterW said:

Just use an optical cleaning material without any abrasive, should get the middle looking better. I’d drop Lunt solar systems EU an email, I got a spare sent over for free even though mine was out of warranty. (If I remember correctly). I’m in the UK. Was a few years ago.

 

Peter

On a couple of mine the damage extended into the glass itself.

[PeterW]

Mine only partially cleared form part of the filter. Never operate why scipe with all the filters in place of course. I am surprised that glass filters go bad, maybe they heat up and react…. I usually assume that doors glass filters are pretty stable.

 

peter