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Lunt Calcium filter

Use this section to discuss "standard" Baader/Coronado/ Lunt SolarView/ Daystar, etc… filters, cameras and scopes. No mods, just questions/ answers and reviews.
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hopskipson
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Lunt Calcium filter

Post by hopskipson » Thu Mar 07, 2019 12:11 am

Hi All

I'm looking to add Calcium K line to my set up. I will be using it on a C-8 and a f/8, 6" refractor with an Aries Tri-band DERF. I will be imaging with an ASI174 or possibly an ASI290.

Will I need to use the blocking filter with the Calcium filter and if so which one would you recommend? Of course I don't want to spend money needlessly so the smallest one that will give good results is my preference.

Sorry if this has been discussed before :oops: , but thanks for the help!

James

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Montana
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Re: Lunt Calcium filter

Post by Montana » Thu Mar 07, 2019 7:49 am

Yes you do need to use the complete unit. There is a guide from Lunt here at the bottom of this page to tell you which size blocking filter to get for your telescope https://luntsolarsystems.com/shop/solar ... k-modules/

My B1800 is absolutely fine on my C11 with the ASI174 chip.

Alexandra

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Re: Lunt Calcium filter

Post by MalVeauX » Thu Mar 07, 2019 7:53 pm

Hey James,

I'll be doing the B1200 module myself. The IMX174 sensor is 11.3mm at it's widest dimension, so the 12mm aperture of the blocking filter will not vignette too badly (don't care about a few pixels around the edge, they will be artifact with stacking anyways). The ERF part of the module is not needed since you will be using a full aperture D-ERF already.

Very best,

george9
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Re: Lunt Calcium filter

Post by george9 » Thu Mar 07, 2019 9:32 pm

I suspect this is in another thread, but have people confirmed that the Lunt ERF doesn't cover a frequency otherwise missed by the main components? Lunt tends to double cover frequencies for eye safety (these are rated for visual), so I would guess it is all covered. I wasn't going to remove the Lunt ERF, but I guess removing it gets rid of one more opportunity for reflections, attenuation, and optical imperfection.

George

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Re: Lunt Calcium filter

Post by bart1805 » Thu Mar 07, 2019 10:09 pm

george9 wrote:
Thu Mar 07, 2019 9:32 pm
I suspect this is in another thread, but have people confirmed that the Lunt ERF doesn't cover a frequency otherwise missed by the main components? Lunt tends to double cover frequencies for eye safety (these are rated for visual), so I would guess it is all covered. I wasn't going to remove the Lunt ERF, but I guess removing it gets rid of one more opportunity for reflections, attenuation, and optical imperfection.

George
Hi George, when visual: safety first. So I would never use my home constructed CaK filter with the Baader Blue and the K-line as blocker for visual. Better safe than sorry so it is just imaging CaK for me. My advise would be (when using visual!) to not remove the 2 inch Lunt nosepiece with the two filters and change it for something else.

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Re: Lunt Calcium filter

Post by george9 » Fri Mar 08, 2019 2:42 am

Oops. Thanks for pointing that out, Bart. I meant for imaging. I cannot see CaK. I just meant that they designed it for visual and they usually double cover everything. So if I use it for imaging, the camera will be fine without the Lunt ERF behind the bigger ERF.

Yes, for visual, my own rule is always use a full commercial setup, optionally adding filters but never subtracting.

George

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Re: Lunt Calcium filter

Post by Valery » Fri Mar 08, 2019 1:58 pm

George and all,

Do not remove Lunt pre-filter unless your image is too dark.


As for camera use for CaK imaging. To realize full resolution at 393nm with IMX174 chip one need to get F/40.
With IMX290 one need to get F/20-25.

I bought 290MM camera for CaK imaging - it has better sensitivity, lower noise and somewhat faster at full size frame. For H-a imaging I still use my Basler ASA1920-155 camera with IMX174 chip.

Hope this helps.


Valery
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Re: Lunt Calcium filter

Post by marktownley » Sat Mar 09, 2019 7:14 am

I'm tempted by a 290 for the same reasons Valery.
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