De-compassing Fujinon FMTRC SX bins

[markse68]

Picked these up for a very good price as the compass was faulty. Don’t need a compass for stargazing so I hoped it would be easy to remove- and it was! These are a really nice pair of bins and now without the annoyance of the intrusive compass, even better.

As they came

The compass body needs to be removed first- don’t have many pics but you have to peel back the rubber from it, unscrew the diffuser cap, pull out the compass cell- it is held in with 3 blobs of silicone rubber, then remove 3 philips screws and pull hard to extract the housing and optical tube assembly from the main body

This leaves a hole- i have gaffer taped it for now but will seal it better at some point

Then you have to remove the graticule which involves first removing the eyepiece- unscrew the rubber eyecup to reveal a treaded locking ring- i used 2 small drill bits and a ruler to loosen it. Remove it and then then pull off the outer focusing grip making a mark for realignment with the eyepiece assembly- a dot of paint on each is what i used. Now you don’t really need to remove the actual eyepiece but i did- it just unscrews. If you do you'll have to play around a bit when you put it back to get the helical thread aligned to match the diopter scale adjustment.

Peel back the rubber cover to reveal 4 philips screws fixing the prism shelf/eyepiece

and pull it straight out from the body- it is sealed so pull hard and be careful not to allow it to rock or you’ll possibly chip the prisms. 

There is a small angled mirror held by 2 screws- remove it. The graticule is held into shelf with 2 small grub screws- after removing them it can be wiggled out without disturbing the prisms.

Screw it all back together and enjoy uncluttered sharp contrasty views.

Mark

Edited August 8 by markse68

[Roberto astro]

Mark, I joined this board to thank you for sharing this, I've found no other resource for this modification.
I have the opportunity to purchase the same bino for a very good price but I'm concerned if I'd butcher it. The compass ruins the intended use unless I get rid of it like you did.

If you'd be kind to answer some questions:
How's the modded bino worked so far for you? 
Do you have any concerns about the weatherproof properties being lost now that you opened the binoculars?

Thank you,

[markse68]

Hi Roberto, thank you! yes I think it definitely does compromise the waterproofness of the bins as there is a ~10mm hole and 3 screw holes exposed by removing the compass. I think on reflection that after having removed the angled mirror and the graticule, it should be possible to replace the compass housing to fill those holes without compromising the fov, though they were sealed with some silicone mastic- maybe some blacktac or similar would make a good enough seal. I haven't re-sealed mine yet but need to think about it. I still need to glue the rubber from the prism shelf back to the main body rubber and do something better than gaffer tape! I guess replacing the compass body will get around the problem of the ugly missing rubber from where it was so i might replace it

They're nice binoculars and are held in quite high esteem by many on astronomy forums- they are certainly very contrasty and sharp. I dont have much experience with really good bins- most of mine are vintage and dodgy condition, but they are nice- sharp to a good way out and without too much distortion at the edge. They're quite heavy for handheld but if you can support them they should be fine.

If you can get them for a good enough price why not!

Mark

[Roberto astro]

I'm a binocular fan, I have a decent 80mm refractor and a 10" dob, love them both but stereo vision and the flexible and engaging nature of binos get most of my time.
my collection include a 6x30 porro, 8x42 and 10x42 roofs, lastly 20x60 and 20x80 porros.
I'm missing the legendary 7x50 configuration and I crave it for the huge 7mm exit pupil. The largest in my collection is the 5.2mm EP of the 8x42s. 

If I take the plunge I'll try removing the mirror and greticle only and report back, hoping the compass alone doesn't affect the FOV. 
If you don't mind me asking, how much did you pay for your 7x50s? 

[markse68]

Hi Roberto, I got mine for a small fraction of the new price due to the non functioning compass- I wouldn’t have done this had it not been for the bargain price I paid. Unfortunately I think you’ll still have to remove the compass to access the graticule as it sticks down into the prism housing and i’m pretty sure would prevent you from removing the prism shelf otherwise.

Mark

[Roberto astro]

OK Mark, thanks for the tip. I just went through with the purchase!
I'm in Mexico where no retailer really offers FMTRs, the market is too small. I suspect the few units here are from people who took the hassle and expense of importing them new. 
I was surprised when I found them on ML (the ebay of this region) and the seller accepted my offer of 4000MXN (around 200 USD).

Pictures and description suggest they're in good condition and the site has a generous return policy. I can't wait to have them and see for myself how they perform  

 

[Roberto astro]

Hello again, I've returned to report on my success! 

I am thankful for this thread and Mark's help. This was a very simple to follow modification and it took me about 30min to complete.
I still have to return to properly sealing the rubber, currently covered by the blue tape. 
As for tools, a few screwdrivers (small) and a picking tool was enough. 

The 7x50 FMRT is truly a beautiful binocular, the views are extremely comfortable, bright and sharp. 
Sure 10 magnifications show more, I will still reach often for this 7x50 and it's relaxed clear views.  

[markse68]

That’s great Roberto- glad it worked for you and that you like them  

Mark

PS where did those extra rings come from- I don’t remember seeing them in mine 

[Roberto astro]

I think they are port of the compass, Mine was functional but I took it all apart for learning purposes. 

I'd report that I didn't need to take the left side eyepiece. However some screws under the rubber were challenging with the eyepiece on the way. So removing it is probably easier.

Roberto