Circles on red element of Lunt blocking filter

paulsartory · Post by **paulsartory** » Thu Mar 16, 2017 2:58 am

Hi all,

I have noticed perfectly circular spots on (in?) the red element of my Lunt blocking filter. I have removed the blue element and mirror so it does not involve them.
You can see the circles using a magnifying glass and shining a bright light through the element. The surface appear completely smooth.
The best description I can give you is like mold in a petri dish except the are perfectly circular (and dark red on red of course)unless they overlap which they do at the edges. This pattern covers 90% of the filter area.
I have contacted Lunt but not heard back yet
Any ideas anyone?

Paul

GUS · Post by **GUS** » Thu Mar 16, 2017 10:22 am

Paul, can you take a photo of it if possible and post it here, might help to identify the problem.

paulsartory · Post by **paulsartory** » Fri Mar 17, 2017 3:32 am

After a bit of messing about I managed to get something useful I think!!

: P3176552 (Large).jpg (176.47 KiB) Viewed 907 times

I haven't used the unit for about 6 months and the blocking filter unit was stored in a plastic box containing desiccant.

Paul

marktownley · Post by **marktownley** » Fri Mar 17, 2017 7:07 am

Are they surface deposits or within the laminated layers of the filter?

paulsartory · Post by **paulsartory** » Fri Mar 17, 2017 7:30 am

Both sides of the filter appear smooth and polished so I assume that it is within the filter.

paulsartory · Post by **paulsartory** » Fri Mar 17, 2017 7:47 am

I have found what looks like a similar problem with the ITF on Coronado's.

marktownley · Post by **marktownley** » Fri Mar 17, 2017 10:08 am

Looks like a return to Lunt to me, definitely send the picture so they can see what is what.

paulsartory · Post by **paulsartory** » Fri Mar 17, 2017 10:45 am

I bought the unit 2nd hand about 18 months ago but I do not know if it is still within 5 year warranty period. I have the warranty card and serial number but it is undated. It was working very well last year (see some of my images posted to this forum) so the defect has only arisen since I last used it (in hot and dry Perth in an airtight plastic box with desiccant) 6 months ago.

I have sent the details, serial# and photo to Lunt and I hope it is just a needs a replacement of the ITF rather than a new B1200 blocking filter.

Paul

astro1949 · Post by **astro1949** » Sun Apr 02, 2017 12:04 pm

any reply from LUNT ?

paulsartory · Post by **paulsartory** » Sat Apr 08, 2017 1:08 am

Yes,

Lunt have asked me to return the blocking filter and will repair it under warranty....excellent result....just got back from 3 weeks holiday in Japan and will get it off to them today.

Paul

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Circles on red element of Lunt blocking filter

Circles on red element of Lunt blocking filter

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