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Camera filters for large (60mm+) binoculars?

Binoculars Filters
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#1 ABQJeff

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Posted 12 May 2021 - 12:09 AM

There are many threads discussing using 2" astronomy filters in 50mm objective binoculars.  However, those with larger objectives (eg 60mm, 70mm, 80mm, 100mm) are left to figure out other options.

 

There ARE optical filters that are 72mm (fits over 60mm objective housing), 77mm (would fit onto a 70mm objective housing), 82mm (fits onto 80mm housing), and larger that can be taped onto the objective housing/dew shield.  These filters are for camera lenses.  Being such, they are optimized for a cmos sensor. But, like all filters, they have a passed spectrum and perhaps could be useful for visual use with binoculars.

 

I myself am trying the ICE LiPo light pollution filter to counter light pollution on my 12x60 and 20x80 Oberwerk binos.  They give a light purple hue, thus do cut out yellow wavelengths, so make seeing stars and bright nebula easier.  But these aren't as strong as a SkyGlow astronomy filter.

 

Another thing I am wondering is if a yellow or 81EF "warm" filter would counter chromatic aberration like a semi-apo or long pass astronomy filter does.  

 

There are a whole number of filters to choose from various vendors, for example:

 

https://tiffen.com/c...ctions/color-fx

 

https://urth.co/coll...ASAAEgLeWPD_BwE

 

 

Questions:

1) have any of you tried camera filters (eg 72mm, 77mm, 82mm, etc.) for your big bino objectives?

2) has anyone done a study of camera filters for visual use on big bino objectives for cutting light pollution, seeing nebula, cutting CA?

3) does anyone know where the passed spectrum for camera filters could be found? (google searching this data, this is not as readily published like astronomy filters where most sites like Baader, Orion, etc. show you the spectrum passed on the filters they sell)  

4) is this just a dumb idea and I should give up on trying to put objective filters on 60mm+ binos?

 

Note: with a spectrum plot you could search and find like spectrum bands for camera filters as astronomy filters, especially skyglow, semi-apo, fringe killer, UHC, H-B, etc.)

 

 

CS!


Edited by ABQJeff, 12 May 2021 - 12:11 AM.


#2 PEterW

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Posted 12 May 2021 - 01:12 AM

Some people in your situation put 1.25” filters in the eyepieces, some binoculars even have threads to enable this. You’ll get greasy filters and may need to add stray light shielding to avoid seeing reflections off them. Gives you access to many more custom options.

Peter

#3 The Ardent

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Posted 12 May 2021 - 01:56 AM

You mean like this? 

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#4 ihf

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Posted 12 May 2021 - 03:20 AM

IIUC placing the filters on the objective side magnifies the imperfections of the filter surfaces. Combining this with the expense of large filters may explain why the approach isn't popular?



#5 ABQJeff

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Posted 12 May 2021 - 03:28 PM

You mean like this? 

Yes like that, here are my 20x80 with the ICE LiPo light pollution filters on...

 

20x80 with filters.jpg

 

Although my gaffer tape is not as 'clean' as your set-up...

 

ICE camera filters...

 

https://www.desphotodist.com/Ice.html



#6 ABQJeff

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Posted 12 May 2021 - 03:36 PM

IIUC placing the filters on the objective side magnifies the imperfections of the filter surfaces. Combining this with the expense of large filters may explain why the approach isn't popular?

Actually camera filters are not that expensive and are of optical quality (for professional photographers using zoom lenses). The ICE LiPo 82mm are $45 ea., the Tiffen 82mm 81EF Warming filters are $102 ea. from adorama

 

https://www.adorama....rce=adl-gbase-p

 

 

Compare those $90 to $200 for a pair prices vs 2" astronomy filters and it is not crazy pricier. 

 

Yes, I know astronomy filters are inch per inch more expensive because of dielectric coatings and tailored high-performance for astronomy, so if those were done for bino objective filters, yes they would be quite a bit pricier.  We are just going for a 'reasonable' substitution because for whatever reason no entrepeneur wants to cater to filters for binos for astronomy, even though us astronomers will drop thousands on APO refractors, eyepieces, mounts, etc.

 

CS!



#7 ABQJeff

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Posted 12 May 2021 - 03:39 PM

Some people in your situation put 1.25” filters in the eyepieces, some binoculars even have threads to enable this. You’ll get greasy filters and may need to add stray light shielding to avoid seeing reflections off them. Gives you access to many more custom options.

Peter

I have read the posts where people did try the 1.25" under the eyecup with the issues you state: can't really mount them well, get dirty easily and most important dielectric filters are designed for light coming perpendicular to the surface.  The latter point can cause stray reflections and odd optical performance when filters placed just inside the eyecup.

 

CS!



#8 The Ardent

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Posted 12 May 2021 - 04:11 PM

My binos have 95mm objective threads. Many camera filters are sized 95mm. 
 

I found some cheap vintage 95mm filters , removed the glass, and asked Dan at DGM for a couple of filters to fit. 

http://www.npbfilter....com/home.html 

 

 

Yes like that, here are my 20x80 with the ICE LiPo light pollution filters on...

 

 

 

Although my gaffer tape is not as 'clean' as your set-up...

 

ICE camera filters...

 

https://www.desphotodist.com/Ice.html



#9 PEterW

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Posted 12 May 2021 - 04:15 PM

How much wallet pain did the custom big nebula filters inflict…. Full aperture would be best and specifically astro bamdpasses wpuld be best.
Peter


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