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Do I really need an IR cutoff filter with narrowband Ha filter?

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#1 adosaj

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Posted 20 January 2021 - 01:47 PM

Hi,

 

I am new to astrophotography and just got a monochrome CMOS camera with LRGBHa filters.  I saw on ZWO’s website that they recommend an IR cutoff filter when using the CMOS camera and also the Ha filter to protect them from IR radiation.  I have a background in astronomy and this seemed a bit dubious.  Do they mean if I was photographing the Sun without an energy rejection filter?  Otherwise the intensity of IR radiation from planets or DSO objects should be very tiny in intensity, no?  Thanks for any clarification.

 

Anil

 



#2 rkinnett

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Posted 20 January 2021 - 01:51 PM

Link?



#3 rkinnett

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Posted 20 January 2021 - 01:57 PM

I think your supposition is correct, they must be referring to additional filtering needed for energy rejection ahead of a solar Ha filter.  No need for any additional filtering whatsoever if you use an Ha filter for imaging anything other than the sun.



#4 adosaj

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Posted 20 January 2021 - 01:58 PM

https://astronomy-im...h-ir-cut-filter

 

Hmmm... now I see the phrase “when doing solar work”, I could have sworn I did not see that last night when I was researching this.  I guess that makes sense.  Should I just delete this post since my question was on a false premise? Sorry, about that.


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#5 bobzeq25

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Posted 20 January 2021 - 02:16 PM

Hi,

 

I am new to astrophotography and just got a monochrome CMOS camera with LRGBHa filters.  I saw on ZWO’s website that they recommend an IR cutoff filter when using the CMOS camera and also the Ha filter to protect them from IR radiation.  I have a background in astronomy and this seemed a bit dubious.  Do they mean if I was photographing the Sun without an energy rejection filter?  Otherwise the intensity of IR radiation from planets or DSO objects should be very tiny in intensity, no?  Thanks for any clarification.

 

Anil

For deep sky imaging, you do not need two filters, just the Ha.  It cuts off excess IR.

 

So do the LRGB filters.  ZWO is talking about color cameras.

 

astronomik-DSLR-ha-filter-wavelengths-44

 

Solar imaging is something COMPLETELY different, needs completely different equipment.


Edited by bobzeq25, 20 January 2021 - 02:19 PM.


#6 Jim Waters

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Posted 20 January 2021 - 02:23 PM

No.




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