Adapting Binoculars for Filter Use.

[Mick H]

Darren Henning (Royal Astronomical Society of Canada) kindly let me share with you a way of to adapt any current binoculars to filter use.

 

I have several APM MS binos that I use with 49mm Kaiser caps (which fit like a glove on the ocular cups when rolled up), and added an insert from ScopeStuff – these are 1.25” filter threaded inserts that I fit into the caps using a Dremel tool:

 

Kaiser lens Caps (49mm fits my APM binos, you’ll have to measure your eye cups rolled back to find size); B&H Photo and several other outlets sell these too. Run about $20-30 USD depending upon sizes needed.

 

 

ScopeStuff TFA1s run around $15USD each If I recall. Shown is reamed out caps and TFA1s ready for insertion:

 

 

Filter thread caps after completion.

 

 

 

 

 

 

 

Caps on my APM 10x50ED MS pair (also fits my 16x70 APMs, and 25x100 APMs (!!)

 

Up to you which way you wish to go. With my APM binoculars and a polarizer or sky glow filter, I lose maybe ~0.1-0.2 degrees of FOV which is a fine trade off  when getting to use filters. Results will vary dep. On eye relief of the pair(s).

 

I hope this is useful for you also! An option that is nice for general bino use, since Oberwerk is the ONLY outfit I know of that offers this filter ocular option!

 

 

 

 

 

Edited February 22, 2022 by Mick H

[PeterW]

Interesting. I achieved something similar using stickyback foam that I stuck to a bit of thin card. The card gives stiffness and can grip onto the thread of the filter. The foam diameter is a little big so it can grip the rubber eyecup…. My first ones had a habit of falling out when observing at high elevations, needed to be a little larger. 
I find that you also need to make sure you block all straylight around your eyepieces as it can really affect the view when you are using strong filters.

 

Peter