Double Stack Lunt CaK filter

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Double Stack Lunt CaK filter

Post by Merlin66 »

Has anyone tried double stacking a Lunt CaK filter to reduce the bandwidth to around 1.2A?
(Using an old PST yellow filter doesn’t count - only current Lunt filters)


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Re: Double Stack Lunt CaK filter

Post by torsinadoc »

I double stacked my b1800 filter


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Re: Double Stack Lunt CaK filter

Post by Merlin66 »

OK.
Do you use two B1800 filters? If so how do you join and align them.
Do you remove any of the secondary filter elements?
Photos?


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Re: Double Stack Lunt CaK filter

Post by torsinadoc »

I used two B1800 filters. ill post a picture of the module tonight

This is the thread I followed (unfortunately the images of the set up have been removed)
viewtopic.php?t=8797



Comparison from last year (DS top and SS bottom). These are unprocessed images

ImageSS DS by Torsinadoc, on Flickr


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Re: Double Stack Lunt CaK filter

Post by torsinadoc »

I took my most recent FD (taken 12-30) image cropped it added shadows and highlights, curves and gamma to bring out some proms. I exposed the original histogram to 80% and didn't try to capture proms. These were not faint. No sharpening was applied. I don't recall the original capture settings
cc.png
cc.png (4.59 MiB) Viewed 5009 times


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Re: Double Stack Lunt CaK filter

Post by torsinadoc »

If there is anything specific you want me to test next time I can image let me know


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Re: Double Stack Lunt CaK filter

Post by Merlin66 »

I would be interested in seeing a photo of the filter setup.
Also, if you could, at the next opportunity, collect an image in DS mode targeting any proms, recording the scope/ camera/ exposure/ stack and any other parameters.

With the SHG I can map the solar surface and the visibility of the proms across the whole CaK wavelength. I'm trying to establish a correlation between bandwidth, offset to CWL and the ease (or otherwise) of imaging proms.

I can obtain comparison images at approx 0.18A bandwidth every 0.2A across the K3/ K2/K1 regions.
Outer CaK wing 1A off centre (K1)
Outer CaK wing 1A off centre (K1)
092514K1v17_shift=0_clahe.jpg (205.38 KiB) Viewed 4981 times
The K1 at +/- 1A shows sunspots and faculae similar to a single stack Lunt image (2.2A ) Proms and filaments very difficult.
Outer CaK wing 0.5A off centre (K1)
Outer CaK wing 0.5A off centre (K1)
092514K1v7_shift=0_clahe.jpg (223.72 KiB) Viewed 4981 times
At K1 around +/- 0.5A starts to show more "flocculation" typical of a double stack system around 1A. Some filaments and proms.
CaK core at 0.2A (K2)
CaK core at 0.2A (K2)
092514K2v3_shift=0_clahe.jpg (224.47 KiB) Viewed 4981 times
At K2, 0.2A from the CWL the surface texture is now showing the activity and filaments. Filaments and proms visible.
CaK on CWL (K3)
CaK on CWL (K3)
092514K3_shift=0_clahe.jpg (212.9 KiB) Viewed 4981 times
Finally on the CaK central wavelength - texture more prominent, filaments and proms easily visible.

Obviously the wide bandwidth filters are a combination of all these wavelengths.

The recording of the proms is influenced by the significant background light with no prom detail found in the K1 regions, the wider the bandwidth the more difficult the proms.
Your SS images look like the K1 at 1A offset, and the DS shows similarities to K1 at 0.5A offset.
Ken


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Re: Double Stack Lunt CaK filter

Post by torsinadoc »

Here are the images. I needed to get an adapter since both ends were male. I assume I performed this mod correctly.
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IMG_0081.jpg
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Re: Double Stack Lunt CaK filter

Post by OlegLviv »

torsinadoc
very good!

Which telescope and camera you use?


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Re: Double Stack Lunt CaK filter

Post by torsinadoc »

OlegLviv wrote: Fri Jan 28, 2022 8:35 am torsinadoc
very good!

Which telescope and camera you use?
102 f11 achromat masked to 60. If seeing allows I can get good results at full aperture. I use a zwo 1600 for FD and zwo 290 for close ups.


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Re: Double Stack Lunt CaK filter

Post by OlegLviv »

torsinadoc wrote: Fri Jan 28, 2022 9:02 am
OlegLviv wrote: Fri Jan 28, 2022 8:35 am torsinadoc
very good!

Which telescope and camera you use?
102 f11 achromat masked to 60. If seeing allows I can get good results at full aperture. I use a zwo 1600 for FD and zwo 290 for close ups.
Why you masked to 60mm? Because CAK love f20?


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Re: Double Stack Lunt CaK filter

Post by torsinadoc »

OlegLviv wrote: Fri Jan 28, 2022 11:13 am
torsinadoc wrote: Fri Jan 28, 2022 9:02 am
OlegLviv wrote: Fri Jan 28, 2022 8:35 am torsinadoc
very good!

Which telescope and camera you use?
102 f11 achromat masked to 60. If seeing allows I can get good results at full aperture. I use a zwo 1600 for FD and zwo 290 for close ups.
Why you masked to 60mm? Because CAK love f20?
My scope is pretty well corrected at 393 even at 102mm but my seeing rarely allows imaging in Cak at 102mm. Cak at 102mm is equivalent to approx 170mm in Ha ((656/393)*102mm). I am close to critically sampled when the scope is masked to 60 with the zwo 290 (80mm mask is the best if seeing allows).

https://brierleyhillsolar.blogspot.com/ ... pling.html

Here is an interesting thread

viewtopic.php?t=25115


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Re: Double Stack Lunt CaK filter

Post by OlegLviv »

Thank you for answer and interesting link!

In my mind ERF for 100 mm refractor CAK do not need?
Why do you decided buy Lunt but not Quark?


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Re: Double Stack Lunt CaK filter

Post by torsinadoc »

OlegLviv wrote: Fri Jan 28, 2022 2:12 pm Thank you for answer and interesting link!

In my mind ERF for 100 mm refractor CAK do not need?
Why do you decided buy Lunt but not Quark?
I use an ERF above 100mm. I have only had seeing twice to support it. I had prior negative experience with a daystar quark and decided to stick with the Lunt.


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Re: Double Stack Lunt CaK filter

Post by Merlin66 »

Oleg,
The Quark offering is a CaH filter, not CaK and is 5A bandwidth - double that of the Lunt.
https://www.teleskop-express.de/shop/pr ... ilter.html


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Re: Double Stack Lunt CaK filter

Post by OlegLviv »

torsinadoc wrote: Fri Jan 28, 2022 8:53 pm
OlegLviv wrote: Fri Jan 28, 2022 2:12 pm Thank you for answer and interesting link!

In my mind ERF for 100 mm refractor CAK do not need?
Why do you decided buy Lunt but not Quark?
I use an ERF above 100mm. I have only had seeing twice to support it. I had prior negative experience with a daystar quark and decided to stick with the Lunt.
I understand you because had Quark chromosphere and had PST mod1 and PST better more contrast+you can put differents barlow :band

You say above 100mm for CAK ERF, or you mean for HA?


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Re: Double Stack Lunt CaK filter

Post by marktownley »

For 100mm ERF CaK you just need to use a uv/ir filter that passes Ca mounted high on the snout of the filter assembly in the focuser.


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Re: Double Stack Lunt CaK filter

Post by Merlin66 »

I use a 2" Baader Blue CCD filter (https://www.baader-planetarium.com/en/b ... blue).html ) with a 2" Astronomik L1 UV-IR filter as a ERF on the DIY CaK filter setup.
Can we get back on track and limit this discussion to Lunt filters and double stacking.
Thanks


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Re: Double Stack Lunt CaK filter

Post by torsinadoc »

Seeing was terrible. I had to use the Apollo M Max (imx 432)+ 102 F11 (masked to 60). I am under sampled but here are some images.

First thing I noticed when I tried to push the settings for the prom was a reflection (double image?) that obscured some of the proms. I added a quick tilt adjuster between the two modules and adjusted it to push is off (I will try and 3d print a solution. As an aside, i really like this camera. The data is so clean

scope: Canadian Telescope 102/1100 fraunhofer achromat masked to 60
Camera: Apollo M Max (imx 432)
Sharp Cap pro
AS3! 40/1000 images



Unprocessed image



Imageunprocessed Calcium Prom by Torsinadoc, on Flickr


Camera Settings
[Apollo-M MAX (IMX432)]
FrameType=Light
Binning=1
Colour Space=MONO8
Capture Area=1608x1104
Output Format=SER file (*.ser)(Auto)
Pan=0
Pan=0
Flip=None
Temperature=25.7999992370605
USB Speed=100
Offset=80
Frame Rate Limit=Maximum
Analogue Gain=314
Exposure=10.0000ms
Timestamp Frames=Off
Background Subtraction=Off
Planet/Disk Stabilization=Off
Banding Threshold=35
Banding Suppression=0
Apply Flat=None
Subtract Dark=None
Display Black Point=0
Display MidTone Point=0.5
Display White Point=1
Notes=
TimeStamp=2022-01-29T17:39:30.4046869Z
SharpCapVersion=4.0.8604.0
StartCapture=2022-01-29T17:39:30.3975598Z
MidCapture=2022-01-29T17:39:32.1305598Z
EndCapture=2022-01-29T17:39:33.8643555Z
Duration=3.467s
FrameCount=344
TimeZone=-6.00


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Re: Double Stack Lunt CaK filter

Post by Merlin66 »

Thanks for that.
The image was then a stack of 40 x 10ms exposures =0.4 sec? gain=314
(The log file only shows 344 frames???)


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Re: Double Stack Lunt CaK filter

Post by torsinadoc »

That is correct. The videos were exposure 10 ms and gain of 318. I took eight separate videos. Some were longer than others. They all had the same camera settings but the duration was shorter on a few. This image was stacked with the above settings


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Re: Double Stack Lunt CaK filter

Post by OlegLviv »

Nice camera! :seesaw
Last edited by OlegLviv on Tue Feb 01, 2022 12:19 pm, edited 1 time in total.


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Re: Double Stack Lunt CaK filter

Post by torsinadoc »

OlegLviv wrote: Mon Jan 31, 2022 8:10 am Hello! Why do you bought How Apollo-M MAX (IMX432)?
How Apollo-M MAX (IMX432) versus ZWO 290MM?
Thank you!
Sent DM


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