Ha filter and IDAS LPS2 Filter together?

[dugnsuz (Doug)]

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

[chunky (Clinton Wood)]

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

[dugnsuz (Doug)]

Originally Posted by chunky

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