26 replies to this topic

[Mike Angel]

Greetings everyone. First Time posting here. I have these 20x binoculars which I've been using for quite a while. Well, it seems they inevitably all become in need of cleaning and some servicing. Left eye vision became noticeably cloudy. So I took upon the task of cleaning them. I've already cleaned all available surfaces, objective lenses, eyepieces, and removed some gunk, all without fully removing the prisms. The image got a little bit better, but ultimately it was evident that there was some fogging on the air gap, on the surface of the hypotenuses. I dare not remove the prisms yet. They have the usual leaf strap, but also a strip of glue. I wonder if I can just try and clean them anyway, probably cracking the glue, perhaps hoping they will stay in place after I reinstall them. Would the leaf strap be sufficient to hold it in place? I'd probably only remove one prism, in order to access the surfaces of the hypotenuses on both prisms, which I couldn't clean otherwise. I include a few low res photos, as I had to screenshot and crop them to make them smaller and add them to the post. I think it's quite visible how fogged they look. I'll still try to post larger ones .Thanks for any recommendations. 

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[Mike Angel]

Here I managed to make a higher res image of the prism. As I said, I believe it's the hypotenuse, just under the circular window, on the air gap where the two prisms meet, where the fogged surfaces still affect the view. There seem to be some streaks, which I don't think it's from my cleaning, but from fogging and condensation forming and evaporating repeatedly over the years. So that's the part I must access to fully clean the thing. More visible also is the glue. It doesn't seem to be much, and I wonder how I might try to lift the prism from the housing with that glue there, I don't think it's going to be too hardened up. I suspect the vertical lifting movement should "unstick" it, cracking the glue and releasing the prism. And again, hoping that the prism will stay in place once I reassemble the bino. I don't have any extra glue, I've read epoxy might work? Is the glue being there really that indispensible? Do I need some special type of glue?, And I can only hope my beginner's diagnostic and troubleshooting of the prisms is correct. Having already cleaned all other surfaces, this has to be it.

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Edited by Mike Angel, 06 July 2025 - 06:45 AM.

[pat in los angeles basin]

Can I assume that you have only accessed the forward facing prism assemblies by removing the objective tubes and the forward prism covers? That you have taken the focuser/ eye piece assembly and arms off the rear of the bino to gain entrance to the rearward prisms after taking off the rear prism covers? At the very least, you will have to remove one prism on each side to gain access to most of the surfaces that need to be cleaned. That means if there is a cement holding the prism in  the  prism shelves, there are 2 strong chances that when you clean those prism and reinstall them there a likelyhood that getting the prisms back in the same exact spot is going to be difficult to manage. If one is off slightly, the merging of the images will be quite a bit of work. Sometimes if you can loosen/remove the spring clamp that's held in place by a screw at one end and a slot on the other side, you can gently break the prism loose from the cement such that reassembly can be a simple matter of fitting the prism with the cement fracture marks precisely aligning. Each prism must be fitted to the respective place (and orientation) that it was removed from. Any sizing variations can make it difficult to achieve the exact position it had prior to removal.

If the bino had good alignment in the first place, work on one side at a time, that will allow you to have one "good" side to compare against the cleaned "reset" side. The cement may be there  for 2 purpose- 1- to finalize the location of the prism after the final alignment, 2- possible visual verification that the prism hasn't shifted if one can open  the binocular up and check to find any of the cement rattling around loose inside the bino or you can physically see the detachment of the cement from the prism- kind of gives you a good indication if which side might be out of whack.

 Even the eyepieces may need cleaning- 

 

Regards, Pat

[Mike Angel]

Can I assume that you have only accessed the forward facing prism assemblies by removing the objective tubes and the forward prism covers? That you have taken the focuser/ eye piece assembly and arms off the rear of the bino to gain entrance to the rearward prisms after taking off the rear prism covers? At the very least, you will have to remove one prism on each side to gain access to most of the surfaces that need to be cleaned. That means if there is a cement holding the prism in  the  prism shelves, there are 2 strong chances that when you clean those prism and reinstall them there a likelyhood that getting the prisms back in the same exact spot is going to be difficult to manage. If one is off slightly, the merging of the images will be quite a bit of work. Sometimes if you can loosen/remove the spring clamp that's held in place by a screw at one end and a slot on the other side, you can gently break the prism loose from the cement such that reassembly can be a simple matter of fitting the prism with the cement fracture marks precisely aligning. Each prism must be fitted to the respective place (and orientation) that it was removed from. Any sizing variations can make it difficult to achieve the exact position it had prior to removal.

If the bino had good alignment in the first place, work on one side at a time, that will allow you to have one "good" side to compare against the cleaned "reset" side. The cement may be there  for 2 purpose- 1- to finalize the location of the prism after the final alignment, 2- possible visual verification that the prism hasn't shifted if one can open  the binocular up and check to find any of the cement rattling around loose inside the bino or you can physically see the detachment of the cement from the prism- kind of gives you a good indication if which side might be out of whack.

 Even the eyepieces may need cleaning- 

 

Regards, Pat

All of it, is exactly what I did. I did go through it slowly, through a process of elimination so to speak. I had never disassembled any binoculars before, so I just went with the limited knowledge I have.

First, I removed the eyepieces, of course by disassembling the screw that holds them. Each eyepiece is one solid piece with its eyeguard ring thing, focuser, and its arms. Plastic though. But all the lenses themselves are glass of course. I cleaned them, and assembled them back. Then I chose to clean the prism surfaces that were immediately reachable from the eyepiece side.

 

And after that, I unscrewed the objective tube part, cleaned the objective lenses and the prism surfaces that could be easily accessed from the objective side.

 

After doing all this, which took me the span of one week, It's still foggy.

 

And looking into the left prism from the objective/front side, it does look dirty.

 

So that informed me beyond all doubt that I had to go through the dreaded task of removing at least one prism. 

 

The eyepieces and objectives are clean as they can be. It's the left side that looks foggy.

The right side has some slight fogging but it's tolerable.

I even made the test of putting the left eyepiece on the right side and looking through it. And the image looked quite fine.

 

So that eliminates eyepieces as the source of foggy vision.

 

Such was the more or less detailed process of cleaning the binos.

 

Your information about the glue/cement is very useful of course. It all points to the things I suspected I had to do, but still needed to have more clear confirmation and information about it. 

 

From my limited knowledge and the several instruction videos and websites I've sifted through, that's the part that has been most confusing.

 

As far as I can gather, it seems I should be able to remove at least one prism, breaking the cement, that way one gains access to the hypotenuse of both prisms.

By using the fracture line on the cement, one should be able then to align it as it was before. Held securely and firmly only by the metal spring/ leaf strap thing.

 

So, from all the information I've gathered, and still gathering, it seems the binoculars should be able to function without that glue/cement. 

 

Difficult as it might be to realign the prism, but possible.

 

Again, that's the part of the process I dread the most, but it's likely I will try it, ever so carefully, within the next weeks.

 

The right side prisms shall remain untouched of course.

 

And well, thanks a lot for your advice!

Edited by Mike Angel, 07 July 2025 - 09:03 AM.

[pat in los angeles basin]

do you know at this stage as to the method that the binocular has to adjust the images? The less expensive porro usually employs a couple of tilt screws per side to enable the adjustment of the 2 prisms. There will be a screw (sometimes hidden under the edge of the armor as that's something that's only needed for access when there's a problem with the alignment). n that when screwed in or out  slightly changes the tilt of the prism, which changes the image merge when viewed through the eyepieces. It can be hard to find the tilt screws as many of the better quality porro binos don't employ such a manner of image adjust. Some have eccentrics on the objectives to shift the image. With the rear prism cover and front prism cover off a zeiss framed bino, you may be able to see if there is a screw present hitting the side of the prism. 

 Here's a short video as to where the prism tilt screws may be on a binoculars that employs such a method

 https://www.youtube....h?v=XyVzYpTYWM0

 

Unless you post  a pic of the particular bino  you are working on and the specs  for the bino, it's going to be a  bit of a guessing game as to what you are going to need to do after cleaning to get the images to merge. Pat

[Mike Angel]

do you know at this stage as to the method that the binocular has to adjust the images? The less expensive porro usually employs a couple of tilt screws per side to enable the adjustment of the 2 prisms. There will be a screw (sometimes hidden under the edge of the armor as that's something that's only needed for access when there's a problem with the alignment). n that when screwed in or out  slightly changes the tilt of the prism, which changes the image merge when viewed through the eyepieces. It can be hard to find the tilt screws as many of the better quality porro binos don't employ such a manner of image adjust. Some have eccentrics on the objectives to shift the image. With the rear prism cover and front prism cover off a zeiss framed bino, you may be able to see if there is a screw present hitting the side of the prism. 

 Here's a short video as to where the prism tilt screws may be on a binoculars that employs such a method

 https://www.youtube....h?v=XyVzYpTYWM0

 

Unless you post  a pic of the particular bino  you are working on and the specs  for the bino, it's going to be a  bit of a guessing game as to what you are going to need to do after cleaning to get the images to merge. Pat

I do not know at the moment if there are more mechanisms or parts for adjusting the prisms. The video you have linked to, is quite helpful, along with the information about adjustment or collimation screws. I had a vague idea of that at best. The binos on the video look remarkably similar to my own. They are a of a make called "Lobo" I do not have a the moment a proper set of screwdriver or tools. I managed to unscrew the eyepiece screw by hand, and I used swabs and wipes to do the cleaning. I must say, I did really did not remove the eyepiece guard itself. There was sufficient access to the prisms on that side just by removing the eyepiece. The guards from the objective sides are not secured by any screw, they pop out by themselves after unscrewing the objective part. The objective side, that's the side where I plan to do the cleaning and removal of the prism. Again, that video and that knowledge about the adjustment screws is amazingly helpful. Lots of thanks again. I will try to include here more photos. I will approach all of this slowly, I will have to purchase a set of screwdrivers and other tools I do not even know the name of, before I attempt to do any further dissassembling.

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Edited by Mike Angel, 07 July 2025 - 11:52 AM.

[Mike Angel]

And, from the left objective side, side up, which is the one I plan to do the removal of one prism and the cleaning.

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[pat in los angeles basin]

On the 2nd pic - the shot  with the objective removed along  with the prism  cover plate removed. If there is a tilt screw, it should be closely poitioned to the tab with the screwhole - the portion in shadow- if  you shine a light down there, a tilt screw should be apparent going from the inside surface of the binocular body  (typically through a thicker portion of the bino body - a slight rib) to the side  of the prism close to the peak of the prism.

[Mike Angel]

On the 2nd pic - the shot  with the objective removed along  with the prism  cover plate removed. If there is a tilt screw, it should be closely poitioned to the tab with the screwhole - the portion in shadow- if  you shine a light down there, a tilt screw should be apparent going from the inside surface of the binocular body  (typically through a thicker portion of the bino body - a slight rib) to the side  of the prism close to the peak of the prism.

There certainly appears to be a screw, it's quite small, but it's there! With this new knowledge, I do think I have a good chance of properly realigning the prism. More options for fine tuning its position are now open with these adjustment screws. It's very likely, again, that I will take at least a few weeks before proceeding to the removal of the prism. (It actually took me two years before finally deciding to try and clean them. Only started cleaning about two weeks ago!) Again thanks for your amazing advice. I would have probably not paid much attention to the screw, or worse I would have just overlooked it completely and scratched or damaged the prism by not noticing it was there, or the importance and function it has. I will certainly post the results once I get through the task. At this stage, I'm still at an impasse, and focused on gathering as much critical information, tools and knowledge before I do anything else to the bino. I include another photo. Hard to see, but it's there. Again, very grateful for all the detailed suggestions, knowledge and spot on advice.

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[pat in los angeles basin]

Glad to read that it has woorked out for you. Back in the day before they seemed to put the rubber armor on the entire exterior on the binocular body, it was fairly easy to locate the discontinuity in the pebble  finish of the body, use a small scraper to pull out the wax sealer, and have access to the screw adjust. Now  you may have a choice to  make - cut hole in the armor right over the adjust screw,or peel the armor away, probably remove entire armor as there are 2 screws per side you will need to access unless the deviation is small. Both have their downsides-  choices, choices.  Pat

[a.palfreyman]

See if the rubber will lift or can be pushed to one side. I have some Chinese Meade 10x50 where you can put the flat tip under the edge of the rubber, prise a bit to access the gate of the screw and then upright the driver for adjustments.

Edited by a.palfreyman, 10 July 2025 - 11:00 AM.

[Mike Angel]

Glad to read that it has woorked out for you. Back in the day before they seemed to put the rubber armor on the entire exterior on the binocular body, it was fairly easy to locate the discontinuity in the pebble  finish of the body, use a small scraper to pull out the wax sealer, and have access to the screw adjust. Now  you may have a choice to  make - cut hole in the armor right over the adjust screw,or peel the armor away, probably remove entire armor as there are 2 screws per side you will need to access unless the deviation is small. Both have their downsides-  choices, choices.  Pat

Choices indeed. But I will be doing all of this quite carefully and thoroughly. With some luck I might not need to further dismantle the bino. At the beginning of the process, I thought I would've been able to perform sufficient cleaning by hand, without much dismantling of the bino. In the meantime, I'm still at an impasse it seems, until I get at least the proper tools. Again, thanks.  

[Mike Angel]

See if the rubber will lift or can be pushed to one side. I have some Chinese Meade 10x50 where you can put the flat tip under the edge of the rubber, prise a bit to access the gate of the screw and then upright the driver for adjustments.

My binoculars seem to be of the exact model as these, except 20x50. They are most probably of chinese manufacture as well. The screws must be in the same exact spots. Mine also has those rubber square pads, and the same rubber decorations covering the rest of the bino. Even the focusing wheel has the exact pattern. Thanks for the very helpful photo examples.

[LoveWillSteerTheStars]

Glad to read that it has woorked out for you. Back in the day before they seemed to put the rubber armor on the entire exterior on the binocular body, it was fairly easy to locate the discontinuity in the pebble  finish of the body, use a small scraper to pull out the wax sealer, and have access to the screw adjust. Now  you may have a choice to  make - cut hole in the armor right over the adjust screw,or peel the armor away, probably remove entire armor as there are 2 screws per side you will need to access unless the deviation is small. Both have their downsides-  choices, choices.  Pat

Two screws per side - only 1 screw per prism?  That seems unable to adjust both axes of the prism. And allow wobble about the point of contact.

 

Are the prism slots generally machined properly at a 90 degree angle?  If so you would just need to push each prism firmly against one long edge.  But if the machining is off, then at least one prism must be installed a little cockeyed... ?

 

And I guess working on the eyepiece side prism is easier, because when looking at the grid paper to confirm 90 degree parallel lines, its just easier to put the objective onto the paper.

Edited by LoveWillSteerTheStars, 12 July 2025 - 10:54 PM.

[Mike Angel]

Two screws per side - only 1 screw per prism?  That seems unable to adjust both axes of the prism. And allow wobble about the point of contact.

 

Are the prism slots generally machined properly at a 90 degree angle?  If so you would just need to push each prism firmly against one long edge.  But if the machining is off, then at least one prism must be installed a little cockeyed... ?

 

And I guess working on the eyepiece side prism is easier, because when looking at the grid paper to confirm 90 degree parallel lines, its just easier to put the objective onto the paper.

I will take this into account when I finally get on to the task. It's very likely the prism, either on the eyepiece or objective side, will require repeated adjustments, until finally getting it correctly positioned. 

[a.palfreyman]

Two screws per side - only 1 screw per prism?
Yes. It essentially performs the same task as shimming a prism with foil. Each of the pair per side being 90 degrees gives full adjustment

[LoveWillSteerTheStars]

Two screws per side - only 1 screw per prism?
Yes. It essentially performs the same task as shimming a prism with foil. Each of the pair per side being 90 degrees gives full adjustment

This does not compute.  A screw can only PUSH the prism, up against the edge of the slot opposite the screw.  It cannot SECURE the prism in any other position, say against the edge the screw enters from.  A screw can TIGHTEN against the slot, but not ADJUST to any position needed within the slot.

[pat in los angeles basin]

yes it does compute as the spring loaded upper clamp will allow the prism to move (decreasing the tilt) to the decreasing of the length of the tilt screw protrudingrelaxation of the  prism tilt. On a system where the entire prism is shifted by the 2 end screws  you have to retract one a bit and extend the opother a bi   None of the binos you have had in the past have a prism tilt screws adjustment?   Pat

[LoveWillSteerTheStars]

yes it does compute as the spring loaded upper clamp will allow the prism to move (decreasing the tilt) to the decreasing of the length of the tilt screw protrudingrelaxation of the  prism tilt. On a system where the entire prism is shifted by the 2 end screws  you have to retract one a bit and extend the opother a bi   None of the binos you have had in the past have a prism tilt screws adjustment?   Pat

Nobody has mentioned a spring loaded arrangement, nor having a threaded insert glued to the prism so a single screw can hold any position.  Never seen a photo or diagram of such a spring loaded system, I'd like to.  Got any names of  makers/models that have such?  I've never looked for screws.

[pat in los angeles basin]

Seriously, all the base model consumer grade zeiss framed binos I have are  tilt prism screw adjust. I picked 4 out of  the 7x35 box- 2 kmart  pennys and empire - all 7x35 cheapy zeisss framed and they all have tilt screws.  And unless they have been worked on by other than a pro, you aren't going to see the screws as they are all below the surface of the leatherette/armor.   With all the binos  you have been through none had tilt screw adjust for prisms on a zeiss framed bino? Even a lot of the 15x70 astro binos use the same scheme...Pat

[a.palfreyman]

Nobody has mentioned a spring loaded arrangement...
Scroll up and you'll see the spring retainers.

[LoveWillSteerTheStars]

Nobody has mentioned a spring loaded arrangement...
Scroll up and you'll see the spring retainers.

we are not talking about that piece of bent metal that goes over the prism.  That needs to be removed in order to turn a screw without risking breaking the prism.  Then somehow the prism needs to be fixed in place before installing it again.

 

WWII US military binocular prisms were aligned by placing the shelf with prisms into a hand held fixture with an eye piece to see the grid.  A screw with a cam on the head was used to get alignment.  The prism was staked, then the cam removed & a regular screw used to fasten the shelf to the body.

[LoveWillSteerTheStars]

Seriously, all the base model consumer grade zeiss framed binos I have are  tilt prism screw adjust. I picked 4 out of  the 7x35 box- 2 kmart  pennys and empire - all 7x35 cheapy zeisss framed and they all have tilt screws.  And unless they have been worked on by other than a pro, you aren't going to see the screws as they are all below the surface of the leatherette/armor.   With all the binos  you have been through none had tilt screw adjust for prisms on a zeiss framed bino? Even a lot of the 15x70 astro binos use the same scheme...Pat

Probably 25% of the SGW bins have collimation issues.  Another 10% have other issues besides needing cleaning.  I have not bothered with the "cheap stuff" but if I find the time & interest I'm sure I have several.  Might just chuck them all, out of space to store things.  Its a winter pursuit & I need to clear my work table for other purposes.  Need to source some small boxes to hold partly disassembled bins, stackable.

 

Need to build a collimater per what Rafael did, but I can't open his files because you need a G**gle account to view them.  Also, his excel equation presumes double eccentrics and I don't know how to use it for a single eccentric per side.

[pat in los angeles basin]

that's NOT accurate. The spring clamp on the cheap Japanese made binos has no problem  holding the prism in place AND allowing the  screw to turn to adjust the tilt- It has worked as I described for all intents every time. Forget mil spec for the moment and locate a cheap tasco, penny, kmart  zeiss frame 7x35 and take a gander- it works as described.   Pat

[LoveWillSteerTheStars]

that's NOT accurate. The spring clamp on the cheap Japanese made binos has no problem  holding the prism in place AND allowing the  screw to turn to adjust the tilt- It has worked as I described for all intents every time. Forget mil spec for the moment and locate a cheap tasco, penny, kmart  zeiss frame 7x35 and take a gander- it works as described.   Pat

Really?  The springed metal strip when fully screwed down still allows the prism to slip against screw pressure, without damage?

 

But if you push it too far, with only 1 screw per prism, how do you move it backwards?  The screw will move back, and merely lose contact with the prism.  Or do most bins have two opposing screws per prism?

 

I suppose screw adjusted prisms are not staked?  I don't see how a staked prism, which is still in place against the factory staking, can be out of alignment.  So one should first remove the cover plates looking for one that has jumped the staking ?

 

At present I just can't take apart another bin until I finish the ones on the bench.

Edited by LoveWillSteerTheStars, Yesterday, 04:51 AM.