Blue Filter in Lunt BF1200

[Carbon Brush]

In early 2019 I found I had a cloudy blue filter in the BF1200 attached to my LS60. Apparently a common issue.
I reported it to Lunt and a replacement was sent FOC from Bresser within a couple of weeks.

I thought once I had a new (defect free) filter that would be the end of problems. But no.

Two years on I have a degraded cloudy filter again.
I have emailed Lunt and await a response.

Am I exceptionally unlucky? Is the blue filter an annual service item?
For the record, the scope has not seen much sky. Nothing else in my scope/eyepeice collection is affected.
When the scope is out, I pop a cover over the objective if I am not actually viewing.
The idea of me having 'baked' a filter is a non starter.

I would be very interested to hear comments from other Lunt BF users.

[Ibbo!]

I think it is moisture ingress under the coating.

 

Even if you have to pay for one they are not that expensive.

[GKA]

There was a thread on this not long ago on Cloudy nights. 

https://www.cloudynights.com/topic/773426-lunt-b1200-blue-glass-filter-growth/

[Highburymark]

I store my solar scope with desiccant packets tied around the blocking filter in a small plastic bag. Think it’s particularly advisable if you don’t use the scope much over winter. Haven’t had any problems with blocking filters in 6-7 years. 

[Carbon Brush]

An extract from the Lunt reply....

Lunt Solar Systems has recently changed the BG itself,  with the new iteration chosen to combat said issue when exposed in areas of high moisture or humidity.
Recommendations are to store your blocking filter with desiccant as possible, in dry areas.

Looks like there is/was a moisture degradation problem, now acknowledged.

Lunt also asked me to contact Bresser.

 

 

[Carbon Brush]

OK I contacted Bresser, who replied fairly quickly. They confirmed...

the manufacturer has now changed the design of the blue-glass. It has now a coating to protect it for air-humidity.

Adding that I should approach their UK subsiduary Telescope House.

Nothing like getting passed from pillar to post!

A look at the TH website produced a filter at £13.50 + shipping stating at £3.90.
Filter not in stock - 7/10days. Wonder if it might be coming from Bresser Germany🤔

Anyway. A spare part that is not going to compromise my ability to visit the supermarket.
However, it does appear the days of free and no fuss replacement (for what is now accepted as a dodgy part) are over.

Do I buy two? There is no point.
If Lunt really have fixed the moisture issue, one filter for life is OK.
If the issue has not been solved, my second glass might degrade. Unless it is very carefully stored - drier than everything else astro that I own.

 

[Peter Drew]

I think the blue filter is an ITF not the blocking filter.  If only blocking filters were that cheap!      🙂

[Carbon Brush]

Thanks Peter for your comment.

I'm not sure at all about the filter characteristic.
I know the narrow wavelength Ha is passed by the scope. But whether IR & UV get through? To be blocked by this filter?
There was a CN thread describing it a bit of cheap blue glass.
I also found my 'blue clouds again' experience was not unique.

I carefully tried using the scope without the blue glass. Yes there is always an idiot around!
The image was significantly brighter and there was a lot more scattered light so I didn't try for more than a second or two.

I do wonder if there is anyone who has removed the 'blue cloud' and tried an eyepiece filter. A 1.25" Ha (6/12nM passband) filter, on the basis it has good cut UV/IR cut.

[tooth_dr]

My blue glass replacement also has failed.  Bresser sent me a free one recently.  They didnt mention a new coating.

Solar disks Sat + Sun with Lunt 60mm and QHY268M, and *check your replacement blue glass* - Imaging - Solar - Stargazers Lounge

Edited June 15, 2021 by tooth_dr

[Davey-T]

I got a free replacement from Bresser but that was before the "B" word so things may have changed now.

Dave

[Carbon Brush]

So my new bit of blue glass arrived today.
Delivered from Bresser Geremany, by DPD.

I was expecting a jiffy bag. But it was in the bottom of a cardboard box, about half the size of a shoebox.

I will take on board that the filter may be more moisture sensitive than everything else in my glassware collection. Despite the 'new improved' claims.

Clouding over now - of course.

[mog3768]

I sent an e mail to Lunt about my cloudy filter who told me to contact Bresser

They sent a replacement free of charge, I cleaned the old filter with descaler it looks perfect but have not tried it yet

[PeterW]

I managed to clean the worst of the grot off my filter… still not perfect and got sent a free replacement as many others have. 
Peter