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Baader Calcium K-Line Filter vs Continuum
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Baader Calcium K-Line Filter vs Continuum

Review and Comparisions

Baader Calcium K-Line Filter in 1.25 filter size: The Baader Calcium K-Line Filter arrives in a 9 x 12 sealed plastic envelope with a set of instructions, a sheet of Baader AstroSolar Film (ND 3.8), and the filter which is inside a small plastic filter holder inside a box.  For an average cost of around $ 350.00 depending on where you make your purchase.

PLEASE NOTE: Re-sellers normally make the statement that All Sales Final, due to the inclusion of the solar film. So, if you are not happy with the results - you're stuck. 

Baader Solar Continuum Filter in 2" filter size: The Baader Continuum filter is a 2" filter and arrives in a hard plastic case, inside the Badder box. The filter is designed to screw onto an eyepiece, camera, or other threaded accessories.

The Solar Set Up: Both the K-line and Continuum filters were used with the same telescope, a ZWO-ASI174mm Camera,  a Baader ND 3.0 filter, and a Baader Herschel Wedge mounted on an 80mm refractor.  This helps keep the playing field even, with images taken with the same optics.

Regardless of which filter you use you must have the necessary "white light" filter in place, either at the front or use a Solar wedge.  With the Calcium K-Line, it comes with an 8 x 11 sheet of Baader's ND-3 solar film, regarded as very good quality.

Following my long wait, anticipation, and high expectations I was excited to see just how well this new Calcium Filter performed.  My first challenge was overcoming the back focus issue when using the camera with a nose piece; that did not work.  So, I had to direct mount the camera onto the Baader Herschel Wedge and this presented a second problem. I did not have the proper filter adapter to allow the 1.25 filter to be screwed into the 2" filter holder in my current setup. But, I had a neat workaround - using some dense foam I was able to secure the filter in place perfectly.  After some camera adjustments, I was off and imaging.  

Because both the K-Line and Continuum filters do not have tuning adjustments your images are based on the activity of the sun that day; unlike HA Pressure tuned setups, you can not "tune" anything to increase detail with these screw-in filters. The best you can hope for is use the exposure and contrast setting on your capture camera, or obviously in post-processing to bring out the details.

The Baader Continuum being a 2" design allowed me to screw it directly onto the Baader filter holder into the wedge -  a tedious task made simple by Baader's design.  I now have a filter insert for the 1.25 calcium K shipping from Agena AstroProducts.

A note about Agena AstroProducts - This is by far one of the best online businesses, Super Fast, reasonable prices with excellent customer support.  If you need filters, adapters, even Telescopes don't hesitate to visit and do business. Excellent! here is the link to Agena AstroProducts.


In the side by side comparison, you can see what I believe is the slight increase of details shown in the Baader Calcium K-Line images vs the Continuum filter.  I made several images over the course of days and was very pleased with the details the Calcium K-Line produced, overall the K-Line produces more contrast and renders more detail than the Continuum filter.

Also included in this gallery are other images taken with the Lunt LS80HA double stacked solar telescope along with an image taken with the continuum filter earlier in the year when the sunspots were more active, unfortunately, I did not yet have the Baader Calcium K-Line filter at that time for comparisons.  


Given the price point of the Baader Calcium K-Line and the fact it can only be used for imaging, I feel the Continuum filter is a cheaper solution for the overall enjoyment of the sun's solar spots and sharing with others visually; of course with the correct configuration.  

If you have a need to do imaging rather than viewing then the Calcium K-Line is a great option. To me it seems pricey for what you get, I think most people who are sun watchers will eventually purchase the Continuum and the Calcium K-line and use them both; that is what I did and if you are trying to squeeze all the detail out of white light viewing the Calcium K-Line is something you should consider.

After reading all the hype on the internet about the K-Line I was somewhat disappointed but still happy with the final results. I do see differences in the images produced with this filter and can appreciate what it brings to Solar Imagers everywhere. I wish I had an opportunity to purchase a 2" version, this would at least make my set more streamlined.

I can recommend this Baader Calcium K-Line for anyone wanting to do solar imaging and have some extra $$ you can spare. Look up and keep watching the sky.



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Collapse Expand Comments (2)
Ibrahim Muhammed

Hello and thank you for this quality article.

This is NOT a criticism.

I believe that your calcium-k images will show additional contrast if you use a camera with a sensor whose spectral range includes the near UV completely. For example the Nikon D50.

I have 0 experience with this and am waiting to get my 1 G memory card for my D50 before I can set up.

I am therefore merely making a suggestion based on my studies.


Ibrahim, thanks for the comments and suggestion. It would be a nice project to set up a D50 as you suggested and see the results.

Thanks again.

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