Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Do I need a UV/cut filter in addition to duo-band filter?

  • Please log in to reply
8 replies to this topic

#1 dagree

dagree

    Lift Off

  • -----
  • topic starter
  • Posts: 6
  • Joined: 21 Apr 2020

Posted 20 July 2022 - 08:39 AM

Hi people

 

I know that this sounds like a dumb question, so please bear with me if it is.

 

I am shooting with a full spectrum (no UV/IR cut filter) modified Sony a6000 and a duo-band filter (STC Astro Duo-Narrowband Clip Filter) that should only let in light around 500nm (OIII) and 656 (Ha). However, I recently noticed in the documentation of the filter that it also lets in light below 350nm. As my camera is full spectrum, I am not sure if light in that range is being filtered and if it is a problem for my astrophotography if it is not being filtered - any experts who can help me answer that?

 

I guess I could always add a UV/IR cut filter on top to be on the safe side, but the less glass the better.

 

Thanks,

Niels

 



#2 bobzeq25

bobzeq25

    ISS

  • *****
  • Posts: 34,480
  • Joined: 27 Oct 2014

Posted 20 July 2022 - 10:07 AM

Your camera still has a Bayer matrix filter for color over the sensor.  That system has little response at wavelengths shorter than 350.

 

https://pic4.zhimg.c...b7cd5bce2_r.jpg


The filter will block the relevant IR.

 

https://nimax-img.de...d-Filter-2-.jpg

 

So, no.

 

Take home message.  Look at spectral response curves.  Google is a good source.


Edited by bobzeq25, 20 July 2022 - 10:08 AM.


#3 bobzeq25

bobzeq25

    ISS

  • *****
  • Posts: 34,480
  • Joined: 27 Oct 2014

Posted 20 July 2022 - 10:09 AM

Your camera still has a Bayer matrix filter for color over the sensor.  That system has little response at wavelengths shorter than 350.

 

https://pic4.zhimg.c...b7cd5bce2_r.jpg

 

The filter will block the relevant IR. 

 

https://nimax-img.de...d-Filter-2-.jpg

 

So, no.



#4 dagree

dagree

    Lift Off

  • -----
  • topic starter
  • Posts: 6
  • Joined: 21 Apr 2020

Posted 20 July 2022 - 01:12 PM

Thanks, makes sense. 


  • bobzeq25 likes this

#5 buytaert

buytaert

    Lift Off

  • -----
  • Posts: 4
  • Joined: 18 Feb 2019

Posted 25 February 2024 - 08:41 AM

Hello,

 

I am also considering to remove the stock glass form my A6000 to make it sensitive to Ha. Since you did not replace that glass with anything else, I wonder if you are stil able to get focus at infinity with a lens ? Or are you using your camera only with telescopes ?

Did you look for a UV/IR replacement ?

Many thanks for your answer, Jan



#6 Digitaliz.se

Digitaliz.se

    Explorer 1

  • -----
  • Posts: 77
  • Joined: 18 Aug 2021

Posted 25 February 2024 - 09:32 AM

I looked at the spectrum of that filter. I cant see it leta UV in. Where did you find that documentation?

#7 buytaert

buytaert

    Lift Off

  • -----
  • Posts: 4
  • Joined: 18 Feb 2019

Posted 25 February 2024 - 11:05 AM

I looked at the spectrum of that filter. I cant see it leta UV in. Where did you find that documentation?

I am not sure that I understand your question... I have no documentation on the original glass filter that is in place. But if it is removed and not replaced by glass with a similar thikcness, the optical lenght is shortened and the sensor should be moved forward to reach focus when used with a lens (not the case if used with a telescope). Therefor I was looking for a replacement glass with a pass between 400nm to 700nm, because I want to keep using my 135mm lens with this camera.

Are you still using your A6000 with a lens ? If so, can you still reach focus without a replacement of the original glass  ?

Regards, Jan


  • Digitaliz.se likes this

#8 Digitaliz.se

Digitaliz.se

    Explorer 1

  • -----
  • Posts: 77
  • Joined: 18 Aug 2021

Posted 25 February 2024 - 01:14 PM

Sorry,
The filter is just letting Oiii and Ha pass. I looked at the spectrum of the filter so it doesnt matte that the camera is full spectrum modded.

#9 GR-Amateur

GR-Amateur

    Ranger 4

  • -----
  • Posts: 356
  • Joined: 15 Sep 2020

Posted 25 February 2024 - 07:33 PM

Some filter need additional filters, some filters don’t need, an example here below. I have this filter (IDAS NB3) and I confirm that shooting with a full spectrum camera without IV/UV cut filter is a mess. Anyhow, filter makers are usually share the band pass charts and clearly state in the specs whether you need or not an additional filter to shoot with.

Attached Thumbnails

  • IMG_3297.jpeg



CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics