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Author Topic: Baader K-line filter questions  (Read 2001 times)

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Offline smerral

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Baader K-line filter questions
« on: 08:17:46, 20 August, 2011 »
Hi,

I'm thinking of buying a baader K-line filter.  I've done some research and I know that the broader bandpass means that they are no match for a dedicated solar  cak scope or Lunt module.  Nevertheless, I would like to have one and they do double as an excellent Venus filter.  I would be using it on either of my two scopes - Skywatcher ED80 and Mak 127.

Basically I have two questions:

One - Will I get the resolution with a colour ccd camera? The reason I ask is that my Atik Titan colour cam doesn't work very well with Ha on the PST (I use a b/w webcam instead); I understand that this is because I'm only using the red channel and consequently only using 1/4 of the pixels.  I have seen colour images with the K-line, which is also a narrow band filter.  Are these artificially coloured? Will the Atik show the same lack of resolution as it does with Ha?

Two - Bearing in mind that I would only be using this for imaging, would the baader full aperture solar filter I already have for white light be sufficient to use in combination with the K-line, or do I need some specifically designed solar film?

Thanks in advance!

Brian
Celestron Nexstar C8XLT
Daystar Quark Ha unit (chromosphere)
Lunt B600 CaK diagonal
Coronado PSTDS
DMK31, ZWO ASI120MM cameras.

Offline smerral

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Re: Baader K-line filter questions
« Reply #1 on: 11:32:27, 20 August, 2011 »
OK I now have an answer to this from Bernard at MA.  For anyone else that might be interested:


Answers are:

1, No, a comparable colour camera will always have less resolution(around ½) than a mono camera. The K line is in the near UV where many cameras are not that sensitive, especially colour ones!
2, The solar film supplied transmits much more light so I expect you’ll definitely need to use it as opposed to the standard filter, unless you have a very big scope and very sensitive camera ;-)

I'm still in two minds about this filter to be honest.....
Celestron Nexstar C8XLT
Daystar Quark Ha unit (chromosphere)
Lunt B600 CaK diagonal
Coronado PSTDS
DMK31, ZWO ASI120MM cameras.

Offline dm-mas

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Re: Baader K-line filter questions
« Reply #2 on: 18:23:08, 28 May, 2012 »
A bit late replying to this one, but it'll probably be useful as a reference in the future....

I've got a K-line filter & while it's not as good as a dedicated CaK scope it does work. I've used it with different scopes & both solar film & a Herschel wedge & it's fine with either.

If you want to use it for imaging Venus you will need a VERY sensitive camera! I tried it with my DMK21AU618.AS & it struggled a bit (although the sky was slightly hazy at the time.) A Schuler filter is a good alternative & slightly easier to use. Not to mention a lot cheaper! ;)

David.
EQ6 pro & home made pier, with various combinations of the following... 8" & 12" LX200 OTA's, Orion ED80, TS65 quadruplet & Meade AR6 150mm refractors,Orion optics 6" F4 & GSO 8" F4 newts, Coronado Maxscope 60, DMK21 & 41, QHY8, modded 350D, Atik 314L. And not enough space to keep it all in!!!

Offline smerral

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Re: Baader K-line filter questions
« Reply #3 on: 20:39:49, 28 May, 2012 »
Thanks David.  I eventually went for a CaK diagonal for the sun.  I also recently bought an Omega CaK filter from the States.  I think I would really struggle with Venus though as the transmission is below 40%.  Unfortunately it's just about the end for Venus this apparition and I haven't had a chance to try it yet.  What is this Schuler filter?
Celestron Nexstar C8XLT
Daystar Quark Ha unit (chromosphere)
Lunt B600 CaK diagonal
Coronado PSTDS
DMK31, ZWO ASI120MM cameras.

Offline dm-mas

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Re: Baader K-line filter questions
« Reply #4 on: 00:42:23, 29 May, 2012 »
Turns out the Schuler filter has been discontinued...
http://www.astrodon.com/products/filters/photometric_-_schuler/
And replaced by the UVenus filter...
http://www.astrodon.com/products/filters/uvenus_filter/

David.
EQ6 pro & home made pier, with various combinations of the following... 8" & 12" LX200 OTA's, Orion ED80, TS65 quadruplet & Meade AR6 150mm refractors,Orion optics 6" F4 & GSO 8" F4 newts, Coronado Maxscope 60, DMK21 & 41, QHY8, modded 350D, Atik 314L. And not enough space to keep it all in!!!

Offline smerral

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Re: Baader K-line filter questions
« Reply #5 on: 07:41:09, 29 May, 2012 »
Thanks David - something to bear in mind for the future (when funds allow!)
Celestron Nexstar C8XLT
Daystar Quark Ha unit (chromosphere)
Lunt B600 CaK diagonal
Coronado PSTDS
DMK31, ZWO ASI120MM cameras.

 

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