Lunt Ca-K Module with Blocking Filter in Star Diagonal for 2'' Focuser

Lunt Ca-K Module with Blocking Filter in Star Diagonal for 2" Focuser

  (2 Reviews)
✓ 2 year warranty


Out of stock due 4-6 working days

About this product

Model:  lunt_ca-k_diagonal_b600
Part Number:  0553501

Transform your normal astronomical telescope into a Ca-K solar telescope simply by putting the Ca-K module into the 2" focuser of your telescope.

Internal narrowband filters allow for a <2.4 Angstrom bandwidth. The Ca-K wavelength is at the edge of the visible light spectrum for human eyes, so for many people visual observing is difficult therefore the Ca-K module is primarily optimised for imaging where all Ca-K details can be captured.

The Ca-K module is in a 90° star diagonal for 2" focusers. The eyepiece side accepts 1.25" eyepieces and also has a T2 connection.

IMPORTANT: Only for use with refractor telescopes up to 100mm aperture. The refractors must not have corrector lenses at the back. Optical elements like corrector lenses or secondary mirrors of reflector telescopes become very hot by the concentrated solar energy and could be damaged.

Calcium K (Ca-K) telescopes and filters are used to study the wavelength of 393.4 nm. This emission line is one of two that are produced by Calcium just at the edge of the visible spectrum, in a layer that is slightly lower and cooler than the layer viewed in Hydrogen-alpha. The emission line displays areas of super granulation cells that are brightest and strongest in areas of high magnetic fields, such as sunspot activity and active regions. Having the ability to study the Calcium K and the Hydrogen-alpha line provides important insights into the structure, strength, and depth of these active regions.

The Calcium K line is centred at 393.4 nm. This wavelength is considered to be slightly outside the visible spectrum on the UV side. While most people can visually see the violet color of the wavelength, many cannot resolve the contrast due to yellowing of the cornea. People who have had cataract surgery are often able to see considerable detail. But, it is for these reasons that the Ca-K line is typically studied via the use of cameras, which are able to provide stunning details.

Choose the best CaK Module for your Telescope Size and Focal Length:

B600: For telescopes up to 100mm aperture and 540mm focal length

B1200:  For telescopes up to 100mm aperture and 1080mm focal length

B1800:  For telescopes up to 100mm aperture and 1620mm focal length

Customer reviews

Average Rating (2 Reviews):  
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Image taking
24 September 2020  | 

I used the b1200 on a4" f13 refractor with a mono camera and I got some stunning images.

Rating (max 5):  
Fantastic piece of kit - buy one!
05 May 2016  | 

I bought the B1200 diagonal for use with my SW Evostar 120 (stopped down to 100mm). Having read all sorts of stories online of how most scopes don't cope with this wavelength well, this worked superbly. Visually I cannot see very much but for imaging with a mono camera this is superb. Having done some imaging in Hydrogen Alpha and finding it a steep learning curve, this was a refreshing change. Simply pop the diagonal in, add the camera, focus and away you go.

The diagonal itself is well made and feels solid. There is no tuning to worry about as with H Alpha scopes which simplifies the whole process.

In summary, one of the more expensive items of kit I have purchased over the years but I have never regretted it.


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