Question about using Narrowband filters

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jazzin United States of America
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Question about using Narrowband filters

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Post by jazzin »


Can you do something like HaOIIIRGB with a modified dslr? I have a Ha filter and a CLS-CCD filter but was wondering if adding the OIII component would be worth it. And what objects would this combination of filters work on?

Just a thought.

I'll hang up and listen.

Thanks
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Star Dad United States of America
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Re: Question about using Narrowband filters

#2

Post by Star Dad »


I used to use a Cannon-70D with an OIII filter and had good results with it. I can't say I've had such good luck with the ZSO ASI294. Although I have to admit that the OIII filter (as I subsequently read) is actually designed for visual observing. I've been doing more Ha and Hb lately. My list of objects to image doesn't have any OIII targets at this point.
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Re: Question about using Narrowband filters

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Post by STEVE333 »


You can certainly use an Oiii filter with a DSLR. The problem with using a DSLR for this is that the Oiii wavelength falls about half way between the peak of the Green filter and the peak of the Blue filter. So, the Oiii filter will produce about equal signal in the Green image and the Blue image. You will then need to add the G and B images together to get the full Oiii signal. Unfortunately you will get noise from both the G and B images when you add them together with the result that the noise will be sqrt(2) larger than it is for either the G or B image.

That's a lot of words which just mean that it will a bit noisier when the G and B images are added together.

Hope this makes sense.

Steve
Steve King: Light Pollution (Bortle 5)
Telescope + Mount + Guiding: W.O. Star71-ii + iOptron CEM40 EC + Orion Magnificent Mini AutoGuider
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Software: PHD2; APT; PixInsight ***** My AP website: www.steveking.pictures
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