Lunt Cak B1200 mod question

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Alun_H
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Lunt Cak B1200 mod question

Post by Alun_H »

I have a problem of both filters in the nose piece of the Lunt CaK module breaking down,blue mottling visible under bright light,since contacting Lunt
I can return the module to Bresser UK for assessment but have been advised that it may have to be sent to Bresser in Germany and if they cannot
repair it there then the unit will have to go to Lunt Solar in the USA and I have been warned this could take months. After having read about the CaK filter combined with a Baader K-line filter and IR cut filter mounted in a Herschel wedge modification viewtopic.php?t=13052 I have been searching for a K line but have since found that it has been discontinued,so can someone please advise me of a suitable replacement for the K line,would the Altair NUV 7nm filter for instance be a good candidate? For IR block I have an Astronomik 1.25".

Alun


Lunt 50THa solar scope
Lunt CaK B12 module
SW Evostar 72ED for full disk imaging
Sol'Ex SHG
80mm f/7 achromat used with pressure tune module off the Lunt with Lunt 100mm ERF
Bresser 90 f/10 achromat used for CaK & white light imaging & PST mod with Lunt 100mm ERF
Coronado SM40 (pre Meade) and BF10 filter set + SMII 60 richview DS etalon
Skywatcher EQ6 Pro and Ioptron CEM60
Then there is all the night kit which is far too long a list to write up here! :lol:
More images on view on my Flickr page...https://www.flickr.com/photos/alun_h/
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Re: Lunt Cak B1200 mod question

Post by george9 »

This answer is for imaging, not visual:

I see Andover Corporation has a new hard-coated 25mm filter centered at 394nm with 10nm FWHM and very steep sides for just $159. It is OD4 from 200 to 1200nm other than over 90% transmission near 394nm (both H and K lines seem to get through over 93% on their sample). Compare to the Baader K-line double stack, which is 8nm centered at 395 and costs $359 when available.

I am not sure what is rusted versus intact on your Lunt, so I don't know if you can combine what you have with the Andover to get it to work.

George

https://www.andovercorp.com/products/ba ... d-filters/


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Re: Lunt Cak B1200 mod question

Post by Alun_H »

Thank you for the link George,definitely imaging only,I did try to use the module visually when I first got it and being over sixty I could only just make out the blue disk.

Alun


Lunt 50THa solar scope
Lunt CaK B12 module
SW Evostar 72ED for full disk imaging
Sol'Ex SHG
80mm f/7 achromat used with pressure tune module off the Lunt with Lunt 100mm ERF
Bresser 90 f/10 achromat used for CaK & white light imaging & PST mod with Lunt 100mm ERF
Coronado SM40 (pre Meade) and BF10 filter set + SMII 60 richview DS etalon
Skywatcher EQ6 Pro and Ioptron CEM60
Then there is all the night kit which is far too long a list to write up here! :lol:
More images on view on my Flickr page...https://www.flickr.com/photos/alun_h/
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Re: Lunt Cak B1200 mod question

Post by marktownley »

Hi ALun,

The Altair filter should work. The Astronimik needs to be the L1 version. You would need to get as must distance as possible between the remnants of the lunt and the ALtair filter to minimise ghosting.

Mark


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Re: Lunt Cak B1200 mod question

Post by Alun_H »

Hi Mark,

Thank you for clarifying that the Altair should work,I believe I have an L1 filter in my old filter wheel,will dig it out and check,I am hoping to follow the same ideas on the thread I linked to and use the eyepiece turret holding the CaK filter from the Lunt since there is a tilt built in and the L1 and the Altair/Andover will be screwed into the Herschel where the original ND3 filter would have been. So bearing in mind what you say about getting distance between the filters I will make/find various depth adapters to hold the turret and experiment.

Alun


Lunt 50THa solar scope
Lunt CaK B12 module
SW Evostar 72ED for full disk imaging
Sol'Ex SHG
80mm f/7 achromat used with pressure tune module off the Lunt with Lunt 100mm ERF
Bresser 90 f/10 achromat used for CaK & white light imaging & PST mod with Lunt 100mm ERF
Coronado SM40 (pre Meade) and BF10 filter set + SMII 60 richview DS etalon
Skywatcher EQ6 Pro and Ioptron CEM60
Then there is all the night kit which is far too long a list to write up here! :lol:
More images on view on my Flickr page...https://www.flickr.com/photos/alun_h/
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Re: Lunt Cak B1200 mod question

Post by marktownley »

You wont need to use the wedge Alun, that's an old thread, you will lose too much light.

Your filter order should go UV/IR - Altair - Lunt - Camera.

The ghosts will occur between the Altair and the Lunt, so get as much distance as possible between them. The UV/IR and the Lunt can sit quite close.


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Re: Lunt Cak B1200 mod question

Post by Alun_H »

Thank you again Mark,I have plenty of adapters so can build a straight through unit no problem,have also got the Altair NUV on order so should be with me in the next couple of days or so,which means more cloud and rain on the way!

Alun


Lunt 50THa solar scope
Lunt CaK B12 module
SW Evostar 72ED for full disk imaging
Sol'Ex SHG
80mm f/7 achromat used with pressure tune module off the Lunt with Lunt 100mm ERF
Bresser 90 f/10 achromat used for CaK & white light imaging & PST mod with Lunt 100mm ERF
Coronado SM40 (pre Meade) and BF10 filter set + SMII 60 richview DS etalon
Skywatcher EQ6 Pro and Ioptron CEM60
Then there is all the night kit which is far too long a list to write up here! :lol:
More images on view on my Flickr page...https://www.flickr.com/photos/alun_h/
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Re: Lunt Cak B1200 mod question

Post by Alun_H »

Received the Altair NUV 7nm earlier today and the clouds broke to allow me to carry out some testing and put it firstly in the Herschel wedge along with UV/IR block filter with the CaK filter from the Lunt and using the 72ED and QHY5III 178M saw absolutely no Calcium K detail whatsoever,just a white light image of the Sun and I was struggling to not overexpose the image so no light loss here. Then I put the Lunt module back as it was with the original ERF/ITF filters and bang there is all the detail. Then I placed the Altair inside a eyepiece projection body with the Lunt CaK filter and again a UV /IR block giving plenty of distance between the two filters and the Lunt filter and same thing a white light image of the Sun. I even placed a neutral density filter on front of scope so as to allow exposure to be increased to no avail. I will try to use the Lunt diagonal next chance I get removing the ERF and ITF filters and replace with the Altair and UV/IR block adding tilt to the filters to see if that makes any difference.
One point to make is that the Altair has UV/IR block coating as well as anti reflection, I even left the Astronomik UV/IR out and still no CaK detail.
Not as easy a mod as I though it would be.

Alun


Lunt 50THa solar scope
Lunt CaK B12 module
SW Evostar 72ED for full disk imaging
Sol'Ex SHG
80mm f/7 achromat used with pressure tune module off the Lunt with Lunt 100mm ERF
Bresser 90 f/10 achromat used for CaK & white light imaging & PST mod with Lunt 100mm ERF
Coronado SM40 (pre Meade) and BF10 filter set + SMII 60 richview DS etalon
Skywatcher EQ6 Pro and Ioptron CEM60
Then there is all the night kit which is far too long a list to write up here! :lol:
More images on view on my Flickr page...https://www.flickr.com/photos/alun_h/
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Re: Lunt Cak B1200 mod question

Post by John »

Hi Alun,
I tried replacing the B1200 CaK nosepiece with Astronomik blue and Altair NUV or Baader Kline filters to try and reduce what appeared to be astigmatism and had the same experience as you with an intensely bright white light image. I contacted Service Bresser in Germany and Kerin Smith was extremely helpful promptly giving me a repair number and sending a partially completed customs CN23 document and help in completing it. I sent it back 4 weeks ago and was informed today that the service had been completed (they have a Lunt trained engineer) and that it was in the post. I sent it from the Post Office tracked, the longest delay was 2 weeks at Customs in Germany. After my experience I think contacting [email protected] is your best bet.
John


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Re: Lunt Cak B1200 mod question

Post by marktownley »

What other filters do you have in your arsenal Alun? What exposure time were you getting with the overly bright image?

Sounds like a light leak to me in the UV/IR


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Re: Lunt Cak B1200 mod question

Post by Alun_H »

Hi John

Thank you for clarifying you had the same problem. I have been in contact with Bresser in Germany who then put me in touch with Kerin and it was Kerin that advised me of the time period if it had to go to Germany then onto the US if he himself could not do anything,mind you all it is is to clarify whether or not the two mirrored filters are actually breaking down on the inside faces,which to be honest I would not have seen had I not removed the front one in an attempt to add tilt to it to remove the glare when imaging prominences seeing as the module delivers great images.


Lunt 50THa solar scope
Lunt CaK B12 module
SW Evostar 72ED for full disk imaging
Sol'Ex SHG
80mm f/7 achromat used with pressure tune module off the Lunt with Lunt 100mm ERF
Bresser 90 f/10 achromat used for CaK & white light imaging & PST mod with Lunt 100mm ERF
Coronado SM40 (pre Meade) and BF10 filter set + SMII 60 richview DS etalon
Skywatcher EQ6 Pro and Ioptron CEM60
Then there is all the night kit which is far too long a list to write up here! :lol:
More images on view on my Flickr page...https://www.flickr.com/photos/alun_h/
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Re: Lunt Cak B1200 mod question

Post by Alun_H »

Hi Mark,

Using the QHY5III 178 with Firecapture I was on zero gain and only around 0.636-0.708ms before the suns disk was overexposed. I have a 2" Baader UV/IR block which I can try next chance I get,cloud looks to be settled in for the whole of today round here.

Alun


Lunt 50THa solar scope
Lunt CaK B12 module
SW Evostar 72ED for full disk imaging
Sol'Ex SHG
80mm f/7 achromat used with pressure tune module off the Lunt with Lunt 100mm ERF
Bresser 90 f/10 achromat used for CaK & white light imaging & PST mod with Lunt 100mm ERF
Coronado SM40 (pre Meade) and BF10 filter set + SMII 60 richview DS etalon
Skywatcher EQ6 Pro and Ioptron CEM60
Then there is all the night kit which is far too long a list to write up here! :lol:
More images on view on my Flickr page...https://www.flickr.com/photos/alun_h/
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Re: Lunt Cak B1200 mod question

Post by marktownley »

Sounds to me like there is a 'leak; with the altair, which would be perfectly normal with the frequency response stated from them.

Given winter is coming now is the time to send it back if you want to go that route.

I think based on my experience the baader uv/ir wont pass CaK (but try it anyway).


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Re: Lunt Cak B1200 mod question

Post by Alun_H »

Ian at Altair Astro stated that this NUV is much the same spec as the new version of the Baader K line ,so neither of them are suitable for this kind of mod. I will continue with this project as I hate failing,I have found one more shop online with a Baader K line listed so will give them a call Monday to find out if it is actually in stock and if no joy then I will either place order for an Andover filter as George suggested or there is another filter I have just come across whilst searching for K line filters,the Antlia 3nm CaK filter if I can find a dealer with one in stock that is. As to sending the Lunt module back,I have definitely written the warranty off since I had to break the glue holding the eyepiece/filter turret to the body of the diagonal so as to remove it,plus my other thought is if the filters are breaking down and I get them replaced what is there to say a fresh set won't do the exact same thing.

Alun


Lunt 50THa solar scope
Lunt CaK B12 module
SW Evostar 72ED for full disk imaging
Sol'Ex SHG
80mm f/7 achromat used with pressure tune module off the Lunt with Lunt 100mm ERF
Bresser 90 f/10 achromat used for CaK & white light imaging & PST mod with Lunt 100mm ERF
Coronado SM40 (pre Meade) and BF10 filter set + SMII 60 richview DS etalon
Skywatcher EQ6 Pro and Ioptron CEM60
Then there is all the night kit which is far too long a list to write up here! :lol:
More images on view on my Flickr page...https://www.flickr.com/photos/alun_h/
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Re: Lunt Cak B1200 mod question

Post by marktownley »

Your other option is an Edmond optics 394/10 - this is what I use in my CaK module

https://www.edmundoptics.co.uk/p/394nm- ... ter/19784/

These have much better out of band blovking.


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http://brierleyhillsolar.blogspot.co.uk/
Solar images, a collection of all the most up to date live solar data on the web, imaging & processing tutorials - please take a look!
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Re: Lunt Cak B1200 mod question

Post by Alun_H »

Thank you Mark.

Alun


Lunt 50THa solar scope
Lunt CaK B12 module
SW Evostar 72ED for full disk imaging
Sol'Ex SHG
80mm f/7 achromat used with pressure tune module off the Lunt with Lunt 100mm ERF
Bresser 90 f/10 achromat used for CaK & white light imaging & PST mod with Lunt 100mm ERF
Coronado SM40 (pre Meade) and BF10 filter set + SMII 60 richview DS etalon
Skywatcher EQ6 Pro and Ioptron CEM60
Then there is all the night kit which is far too long a list to write up here! :lol:
More images on view on my Flickr page...https://www.flickr.com/photos/alun_h/
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