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Old 09-05-2009, 08:03 AM
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dugnsuz (Doug)
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Location: Hahndorf, South Australia
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Ha filter and IDAS LPS2 Filter together?

Hello all...
My Astronomik 12nm Ha EOS Clip-In filter recently arrived from the states.
Haven't had a chance to try it out yet thanks to the weather though!

Question: Is there any benefit (or disadvantage) to using the Ha filter in conjunction with my Hutech IDAS LPS2 filter in place?

Cheers
Doug
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  #2  
Old 09-05-2009, 08:27 AM
chunky (Clinton Wood)
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Doubling filters up

Hi Doug,

My take on it is that you are using 2 notch filters together. One is a narrow single notch - the other is multi-notch, so all you would be doing would be adding another optic with potential reflection issues and attenuating the Ha signal down another 15% or whatever the IDAS filter is for transmitting Ha. I think the Ha line averages 75% transmission on IDAS filters.

So you would just lose another 1/4 of your Ha light.

Regards
Clinton
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Old 09-05-2009, 08:43 AM
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dugnsuz (Doug)
to baldly go...

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Quote:
Originally Posted by chunky View Post
Hi Doug,

My take on it is that you are using 2 notch filters together. One is a narrow single notch - the other is multi-notch, so all you would be doing would be adding another optic with potential reflection issues and attenuating the Ha signal down another 15% or whatever the IDAS filter is for transmitting Ha. I think the Ha line averages 75% transmission on IDAS filters.

So you would just lose another 1/4 of your Ha light.

Regards
Clinton
Thanks Clinton - I had thought there might be a disadvantage re transmission but hadn't even considered the potential for the addition of more internal reflections!
The least amount of glass between you and the stars is probably a rule of thumb to follow at all times!
Cheers for the response.
Doug
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