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Can you leave in your CLS Filter for Narrow Band?

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#1 Mvillegas

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Posted 24 May 2020 - 07:37 PM

I bought a L-Enhance 2" filter to place in front of my Filter Wheel for when I want to shoot LRGB on my ASI1600MM and wondering if I can leave it in the image train for when I shoot Narrow Band?  

 

I know you dont need CLS for Narrow Band but will it increase my exposure time or in CLS is different wave length?

 

Thanks



#2 xiando

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Posted 24 May 2020 - 07:53 PM

as long as a filter doesn't impinge on another filter's response, I suppose so

 

for instance, 

 

Suppose you added a filter that lops off everything above 800nm, and for the purposes of this conceptualization, the magical ideal filter has an infinite slope wall at 800nm and its pass band is clean 1.000 transmissivity across the entire passband, (ie, anything less than 800nm has a perfect gain of one response, ie, as if nothing was there) 

 

you then apply an OIII filter behind it (ie optically "downstream"). The OIII filter never really sees the high cut filter, because the OIII is only concerned with band passing in the ~500(ish) nm area. well below the cutoff of the first filter.

 

Now in the real world, that pass band for the highend cutoff filter isn't really a perfect 1.000000, and the slope of its cutoff isn't really infinite, but the *principle remains the same.

 

 

I know you dont need CLS for Narrow Band but will it increase my exposure time or in CLS is different wave length?

as for your use and your particulars, I couldn't say




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