Opticron sr ga 8x32 inside (1 Viewer)

[Gypa]

Hi. I recently purchased an Opticron sr ga 8x32 binocular (I'm nostalgic for porro prisms). Until today I did not observe that a white glue appears on both sides in one of the interior joints. Although it does not produce any kind of internal reflection, I would like to know if this appears in all units.
Thanks and greetings
Peter
(Google traductor)

 

[pete_gamby]

Yes it does.

 

[ZeNiTh-PbArM]

Hi,

Mine does, too.
By the way mine has developed focuser backlash which I find annoying. Upon close examination it seems the focuser drum as a little bit of slack in the axis direction, i.e. it slides maybe half a millimeter back and forth, which results in 1/8th of a turn of a focuser without motion.
Can anyone suggest how to disassemble the focusing mechanism? I'd like to compensate for the backlash using washers of calibrated thickness and get rid of this annoying slop.
Thanks
zp*

 

[pete_gamby]

Hi there - having spoken to our service department, you have correctly identified the solution.

However, to disassemble the focus mechanism means a significant number of components can be affected including the central hinge. This could affect collimation. Unfortunately, as a result they are not willing to provide details on the disassembly process but would be happy to service the binocular for you.

If you wish to discuss further please contact Stuart at [email protected] or call +44 1582 726 522.

Cheers, Pete

 

[Steve999]

I had this very focussing issue with my SR GA 8x32's and after conferring with the service dept at Opticron by phone, sent them in to them. I had them back in perfect condition in little more than a week. Excellent service and during the spring Covid lockdown period as well.

Regards, Steve

 

[ZeNiTh-PbArM]

Hi there - having spoken to our service department, you have correctly identified the solution.

However, to disassemble the focus mechanism means a significant number of components can be affected including the central hinge. This could affect collimation. Unfortunately, as a result they are not willing to provide details on the disassembly process but would be happy to service the binocular for you.

If you wish to discuss further please contact Stuart at [email protected] or call +44 1582 726 522.

Good evening,

Today I went ahead and disassembled the whole thing. It's a bit tricky but not as much as I feared it would be based on your description. Here's the thing disassembled :

So how does it work? The drum 5 and inner tube 4 rotate around the hinge pin 3. The piston 6 slides in and out thanks to screw 2 riding in the helical groove of tube 4. Screw 1 indexes drum 5 and tube 4 together and its tip rides in the groove of pin 3, allowing rotation but no sliding in the axis direction.

I sketched things up so it's easier to figure out how it works :

The disassembly process is quite straightforward: rotate drum until screw 2 aligns with the hole in drum 5, then remove screw 2 completely and slide piston 6 out complete with eyepieces. Then remove screw 1, unscrew hinge nut 7 (remove setscrew first!) then slide out hinge pin 3 and the whole thing comes apart. Nothing to fuss about.

Now why does my pair have focus slop? Well, a picture is worth a thousand words. There is a substantial clearance which allows the drum to slide back and forth. With the fast focus mechanism the helix has a very coarse pitch therefore a small amount of play amounts to a big angle on the focuser.

Now here comes the interesting part. The screw being brass and the pin being steel, I assumed the screw was worn out. Wrong! Upon close examination the tip of that screw is perfectly round, shows no flats, no wear at all. It came out of the factory underside!
To hide that manufacturing issue the factory used a liberal amount of damping grease. I guess over time the grease thinned out, and the damping action got reduced and focus slop became noticeable.

So to the lathe I went, and machined a replacement screw with minimal clearance. You'll notice I made the screw a tad longer than the original one, I'll explain why.

So this screw threads into the plastic drum, and plastic threads really are a weak design. I wasn't happy with these so I aligned and glued a custom machined steel nut in the recess for extra strength.

Well I reassembled and lubricated the binoculars using a silicone grease that's a bit less sticky than the original one, and hopefully the focus will stay as is it today : ultra sensitive, no slop at all, and butter smooth. That's how it should have been from the factory...

And I checked alignment, it's as good as it was before, so getting the hinge pin out didn't mess things up.


Have a nice weekend,
zp*

 

[chris6]

zp, thanks that's very interesting and detailed with excellent diagrams and pictures.

Good job!

 

[ZeNiTh-PbArM]

Thanks

I've been enjoying my repaired pair for a few days now. I'm delighted with the results, the binoculars are better than they ever were.
It's quite a shame that such defects which are in plain view of whoever assembles the thing gets temporarily hidden with damping grease, only to fail after a while. Then it takes a lot more time and effort for fixing than it would have originally required.
Well I guess these binoculars are built to a price but there really is no substitute for quality.

Regards
zp*

 

[ZeNiTh-PbArM]

Hi

I've been taking the SRGA for a walk along the river this morning. In spite of the freezing temperature I enjoyed looking at the birds. Here's a pic I shot through the eyepiece with my (inexpensive) smartphone. In spite of the poor lighting and contrast conditions the sharpness of the optics makes the views sharp and crisp.
An elderly gentleman asked for a view, focused on a couple of swans, his jaw dropped. "I didn't know binoculars could be that good" he said.

Regards
zp*

 

[ZeNiTh-PbArM]

 

[pbjosh]

What an excellent thread.

First, cheers to Pete for giving genuine technical advice, for consulting with their service dept, and for being (as always) so on the ball. In my opinion, Opticron is the model of how to represent a brand on the internet and it's a shame that none of Leica, Zeiss, Swaro, Nikon, Meopta, nor Kowa do the same.

Second, cheers to you ZP for the detailed breakdown of what you did and your results. Very interesting to someone with an engineering background but who's never taken apart a pair of bins.

Happy holidays and happy new year to all

 

[Patudo]

Good evening,

Today I went ahead and disassembled the whole thing. It's a bit tricky but not as much as I feared it would be based on your description...

...Well I reassembled and lubricated the binoculars using a silicone grease that's a bit less sticky than the original one, and hopefully the focus will stay as is it today : ultra sensitive, no slop at all, and butter smooth. That's how it should have been from the factory...

And I checked alignment, it's as good as it was before, so getting the hinge pin out didn't mess things up.


Have a nice weekend,
zp*

Congratulations on a fine job sir, and for detailing your work to us!

I don't have the mechanical skills you do, but I know (from rebuilding fishing rods etc) the feeling of taking something and making it better than it was before, and the enjoyment you get in using such things. Your binoscoped shots are excellent too!

 

[Charnwood]

Nice repair job - thanks for sharing the details - and nice pictures too.
How long have you had the binoculars. I’m curious because I have a pair of SRGAs too and I’m wondering if the same problem is in store for mine.

I hasten to add I have no plans on selling them

 

[ZeNiTh-PbArM]

Hi,

I'd say I had the binoculars one year and a half before the problem became obvious and I retired the binoculars from active duty. It then entered the long list of "to be repaired someday" items and it gathered lots of dust waiting on the shelf.
Now they have been repaired, I'd say they feel a lot better than they were initially, which leads me to believe the problem was annoying me from the start but was too faint for me to detect straight away.

Cheers,
zp*

 

[Charnwood]

Thanks. I've only had mine a couple of months and they share duties with a couple of other pairs. Can't detect any slop in the focus yet. I've seen mixed reports in other reviews about the focus so maybe I can hope all the focus screws weren't all undersized like those on your pair.