Binocular filter mounting

[PeterW]

As someone pointed out the lack of clear guidance on adding filters to binocular eyepieces I thought I’d post how I have done the is recently that seems to work.

Different binocular eyepieces have different internal diameters and depths and so you might need to play about to find the best option for your specific model. “Normally” the filter is smaller than the eyepiece/eyecup hole so you want someway to “fill the gap”.

I use 3 mm thick sticky-back black neoprene foam sheet. I stick it to paper/thin card (which I blacken with a sharpie). Then I cut a hole that is slightly narrower than the filter threads. The idea is that you want to be able to “thread” the filter onto the foam ring. Next to cut the outside of the foam ring a little bit larger than the eyecup opening. You want to use the foam compression to help grip and stop the filter falling out. You might want to trim the paper back round the edge so it doesn’t reach the edge to help this.

I put these in with the filter on the binocular side of the foam so if they come off the foam they will be trapped and not fall into the grass.
 This probably  won’t work for all binoculars, I have some 7x50 where a single layer of duct tape wrapped onto the filter threads enables the filter to be push fit to the eyepieces. If the filters are larger than the eyecups then you could probably glue a foam cylinder to the foam ring that you could slide  over the eyepieces to hold the filters in place.

Remember for best use of filters on binoculars you need to block all straylight around the eyepiece  by using a bino bandit, observing hood etc.. or you’ll be distracted by reflections from the filters which will make seeing faint stuff harder.

Hope this helps, sure other people have come across other ways to achieve the same thing. 

 

 

Peter

[Stardaze]

Thanks for sharing Peter, I really must give this a try. 

[PeterW]

When your all shielded up you Cana get better dark adaption than normal as ambient light is blocked. Filter and eyepiece fogging can be a risk, my face shield keeps my breath out and anti-fog spray could also help if needed on cold nights.

 

peter

[Stardaze]

1 hour ago, PeterW said:

When your all shielded up you Cana get better dark adaption than normal as ambient light is blocked. Filter and eyepiece fogging can be a risk, my face shield keeps my breath out and anti-fog spray could also help if needed on cold nights.

 

peter

The bino bandits definitely can accentuate fogging up for sure. Mines been better of late and I can’t say why that’s the case.