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What would that be in the binocular eyepiece lens?

binoculars eyepieces imaging
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#1 Veckbeld

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Posted 12 August 2019 - 11:38 PM

Greetings from Brazil for everyone!

First of all, sorry me for any mistakes in this topic. I had never created one before blush.gif 

Well, could anyone please answer me a question about an "unidentified object" ("UO") in the Pentax 16x50 binocular eyepiece lens?
Ah! And figuring out what it would be...

 

190

 

I bought these binoculars from a friend and, at the time of purchase, I could already notice the UO on the right eyepiece lens. Still, I decided to buy them because I figured it could be something to easily clean up later.
Unfortunately, now I can't reach it, nor identify it. And, when I ask the former owner actually what this UO really would be, he says he had also bought these binoculars with this annoying nuisance in the eyepiece lens.

 

At first sight, it is easy to see that the UO has a shape similar to a "distorted" or irregular triangle, but from the photos posted below (both inside and outside), it is noted that it has no similarities with any dirt, scratch, crack, latch nor fungus.
 

197

191
 

However, I still need to remove this next to last eyepiece lens in order to have APPARENTLY direct access to the last eyepiece lens (which are both depicted in the scheme of photo below) and so get face to face with the UO. How do I get access on this last eyepiece lens?

 

NEW

 

Thanks in advance!


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#2 Cali

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Posted 12 August 2019 - 11:54 PM

Welcome and interesting post, Veckbeld. Hopefully someone will answer your question soon.

 

- Cal


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#3 hallelujah

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Posted 13 August 2019 - 12:04 AM

Can you see through the triangle?

Does it affect the view through the eyepiece lenses to any degree?

 

Stan


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#4 ngc7319_20

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Posted 13 August 2019 - 12:19 AM

This lens is made of two pieces of glass glued together.  The problem is they are becoming unglued, and the two glasses are separating.  Usually the glasses start separating at the edges, and then over time it propagates to the center of the lens. This happens if a binocular is dropped, or if exposed to very hot or very cold.

 

The "UO" triangle is where the two glasses are still attached to each other.  It looks darker there, since light passes through the interface of the two glasses without reflection.  Where the glasses have separated there is roughly an 8% reflection, and it looks brighter there if you shine a light on it.  The interesting color effects around the edges where it has separated are due to the interference of light in the small gap between the glasses.  Where the gap is N+1/2 wavelengths of light, that color is reflected more strongly.

 

It will be difficult to fix this.  You would need to get that lens out of the eyepiece.  Then separate the two elements, clean them, and re-glue them.  Probably a strong solvent like acetone could be used to separate them by soaking for a long time.  Various optical cements are typically used that cure by exposure to UV light.  It is critical to get the two glasses aligned before gluing them.  Probably you could put a tiny drop of the glue between the glasses, reassemble the eyepiece to keep them aligned, and then place the eyepiece against a fluorescent light to cure the glue.  Places like Edmund Industrial Optics sell the glue.

 

First decide if the defect bothers you.  What you may notice is that the view is hazy around the edges, especially during daytime.  If it does not bother you, then leave it alone.


Edited by ngc7319_20, 13 August 2019 - 01:07 AM.

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#5 Antonio R.G

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Posted 13 August 2019 - 03:18 AM

I agree with the previous comments. I have some old binoculars with this problem, in lens edges (in one of them is very extensive..), but after checking several times I can't see any difference with "sane" lens in the same binocular. More problematic lens defect is "bubbles" inside the glass because it don't have solution, only changing the lens. In your problem better don't touch oculars inside if you don't be professional or you have a lot of practice, it's very easy broke or damage the lens.. if defect is only aesthetic leave it to be..
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#6 Veckbeld

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Posted 13 August 2019 - 03:17 PM

First of all, thank you very much for all the quick answers!

 

Can you see through the triangle?

Does it affect the view through the eyepiece lenses to any degree?

 

Stan

Yes, I can see through it.

In this photo it is possible to see the silhouette of the triangle (I think if clicking on it will expand and increase zoom or I could learn some way to post this photo with higher quality) and that inside is transparent.

191.jpg
 

Can you see through the triangle?

Does it affect the view through the eyepiece lenses to any degree?

 

Stan

And the vision is greatly affected.

Let me give you an example.

 

When I aim at Jupiter and its 4 Galilean moons with my Pentax 16x50: with my open left eye and my closed right eye, I can easily distinguish both Jupiter and the 4 Galilean moons (all appearing to be perfect spherical discs); but when I try to see with my open right eye and my closed left eye, I can only see a bright intense light that does not look at all like what was seen in the above test (most likely being Jupiter standing out crazy.gif ), as if there was a dense and irregular fog "INSIDE my binoculars" blurring the whole picture...


Edited by Veckbeld, 13 August 2019 - 03:24 PM.


#7 hallelujah

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Posted 13 August 2019 - 04:25 PM

First of all, thank you very much for all the quick answers!

 

 

When I aim at Jupiter and its 4 Galilean moons with my Pentax 16x50: with my open left eye and my closed right eye, I can easily distinguish both Jupiter and the 4 Galilean moons (all appearing to be perfect spherical discs); but when I try to see with my open right eye and my closed left eye, I can only see a bright intense light that does not look at all like what was seen in the above test (most likely being Jupiter standing out crazy.gif ), as if there was a dense and irregular fog "INSIDE my binoculars" blurring the whole picture...

It might be less complicated, all around, if you just purchase a replacement for the 16x50.

 

Stan


Edited by hallelujah, 13 August 2019 - 04:26 PM.

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#8 ngc7319_20

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Posted 13 August 2019 - 04:53 PM

 

And the vision is greatly affected.

 

OK so it is bad. 

 

An easier fix might be the following.  Get that lens out of the eyepiece.  Make a drawing of which way it went (which way the lens curved).  See if the two cemented glasses will just come apart with a little pushing.  If not, you will need to soak it in a strong solvent like Acetone or 91% rubbing alcohol (Isopropyl Alcohol) until they separate (it might be quick or it might take days).  Clean off the old glue with some solvent until it is pristine. Clean off the other surfaces of the lens, too.

 

Find some thick transparent oil.  A high viscosity synthetic motor oil might work.  Or you can use cooking oil or olive oil, but it might turn cloudy some day.  Put a very tiny drop at the center of the concave element, put the other element over it, and squeeze it so the oil flows and fills the space.  If it does not flow to the edges in a minute or so, take it apart and try again with a larger drop. Once the oil has filled the space, carefully wipe off any excess that came out the sides.  Carefully clean any oil that got on the outer surfaces.  Then reassemble the eyepiece, taking care to get the lenses pointing the correct way (not reversed, etc.).

 

The oil does not need to be perfectly clear, since there is only 0.01mm or so layer.

 

Maybe this will be good enough to use the binocular for a time -- maybe months or years, before the oil needs to be replaced.


Edited by ngc7319_20, 13 August 2019 - 04:55 PM.

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#9 pat in los angeles basin

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Posted 13 August 2019 - 08:43 PM

I did as an experiment the same thing as ngc7319_20 stated in the previous response. I used mineral oil on several objectives - 4 months have passed and I still can't tell which objective has the oil spacing and which has the (presumed) balsam. In my case , the bins had taken a cement floor hit on one objective and separated into the  2 components. A bit of acetone clean up, followed by some goof off and ready for the test, which is still ongoing. Still intend to bond somewhere down the road. Good luck , Pat


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#10 Veckbeld

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Posted 19 August 2019 - 09:09 PM

I'm so sorry for the delay, guys!

 

This lens is made of two pieces of glass glued together.  The problem is they are becoming unglued, and the two glasses are separating.  Usually the glasses start separating at the edges, and then over time it propagates to the center of the lens. This happens if a binocular is dropped, or if exposed to very hot or very cold.

 

The "UO" triangle is where the two glasses are still attached to each other.  It looks darker there, since light passes through the interface of the two glasses without reflection.  Where the glasses have separated there is roughly an 8% reflection, and it looks brighter there if you shine a light on it.  The interesting color effects around the edges where it has separated are due to the interference of light in the small gap between the glasses.  Where the gap is N+1/2 wavelengths of light, that color is reflected more strongly.

 

It will be difficult to fix this.  You would need to get that lens out of the eyepiece.  Then separate the two elements, clean them, and re-glue them.  Probably a strong solvent like acetone could be used to separate them by soaking for a long time.  Various optical cements are typically used that cure by exposure to UV light.  It is critical to get the two glasses aligned before gluing them.  Probably you could put a tiny drop of the glue between the glasses, reassemble the eyepiece to keep them aligned, and then place the eyepiece against a fluorescent light to cure the glue.  Places like Edmund Industrial Optics sell the glue.

 

First decide if the defect bothers you.  What you may notice is that the view is hazy around the edges, especially during daytime.  If it does not bother you, then leave it alone.

Hmm
So are (or were) they glued? That I did not know.
This is very interesting and makes sense. And it looks like someone dropped the poor wretches...

 

wow

These interesting color effects like mini-rainbows lol
And how many details in your post!
I really appreciate it.

 

I got it

Thank you for the walkthrough but how can I get that ocular lens out of the eyepiece?
Look at some pictures below... Maybe in the fifth photo, through these "spaces"?

 

x227.jpg
x228.jpg
x229.jpg
x230.jpg

xxx231x.jpg

 

Unfortunately it bothers me so much!

If my Orion Scenix 7x50 already drives me crazy and makes me want to open and fix everything

when (sometimes) I can't focus it to see Jupiter as a perfect spherical disc, just imagine how I

feel about these Pentax? (By the way, has anyone had any problem like that and managed to solve

it without being by collimation?)


Edited by Veckbeld, 19 August 2019 - 09:19 PM.


#11 Veckbeld

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Posted 19 August 2019 - 09:12 PM

I agree with the previous comments. I have some old binoculars with this problem, in lens edges (in one of them is very extensive..), but after checking several times I can't see any difference with "sane" lens in the same binocular. More problematic lens defect is "bubbles" inside the glass because it don't have solution, only changing the lens. In your problem better don't touch oculars inside if you don't be professional or you have a lot of practice, it's very easy broke or damage the lens.. if defect is only aesthetic leave it to be..

Seriously, Antonio? My condolences! xD
Bubbles? What a madness!
When you have time, could you share with us any picture of this curious problem in your

binoculars?

 

Unfortunately it is not just an aesthetic problem, and of course I will follow your advice to be

very careful. Anyway, I have a certain ease and practice with maintenance such as the one we are

talking about (obviously if it seems too complex I would rather not risk so much).

 

 

It might be less complicated, all around, if you just purchase a replacement for the 16x50.

 

Stan

I agree with you Stan, but unfortunately in Brazil there is no Pentax representative company.
Anyway, I felt quite challenged to/with this problem and quite encouraged enough to try

something before giving up.



#12 Veckbeld

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Posted 19 August 2019 - 09:17 PM

OK so it is bad. 

 

An easier fix might be the following.  Get that lens out of the eyepiece.  Make a drawing of which way it went (which way the lens curved).  See if the two cemented glasses will just come apart with a little pushing.  If not, you will need to soak it in a strong solvent like Acetone or 91% rubbing alcohol (Isopropyl Alcohol) until they separate (it might be quick or it might take days).  Clean off the old glue with some solvent until it is pristine. Clean off the other surfaces of the lens, too.

 

Find some thick transparent oil.  A high viscosity synthetic motor oil might work.  Or you can use cooking oil or olive oil, but it might turn cloudy some day.  Put a very tiny drop at the center of the concave element, put the other element over it, and squeeze it so the oil flows and fills the space.  If it does not flow to the edges in a minute or so, take it apart and try again with a larger drop. Once the oil has filled the space, carefully wipe off any excess that came out the sides.  Carefully clean any oil that got on the outer surfaces.  Then reassemble the eyepiece, taking care to get the lenses pointing the correct way (not reversed, etc.).

 

The oil does not need to be perfectly clear, since there is only 0.01mm or so layer.

 

Maybe this will be good enough to use the binocular for a time -- maybe months or years, before the oil needs to be replaced.

Got it

Really drawing a picture before will help me a lot when closing again.
I hope to be able to find all these reagents first of all.

 

The annoying part is that it would need to replace this oil from time to time, but I agree with

why.
Anyway, I'll try it all yes
Thank you so much for sharing this perfect and detailed step by step.

 

"Get that lens out of the eyepiece"

How? blush.gif

 

I did as an experiment the same thing as ngc7319_20 stated in the previous response. I used mineral oil on several objectives - 4 months have passed and I still can't tell which objective has the oil spacing and which has the (presumed) balsam. In my case , the bins had taken a cement floor hit on one objective and separated into the  2 components. A bit of acetone clean up, followed by some goof off and ready for the test, which is still ongoing. Still intend to bond somewhere down the road. Good luck , Pat

Thank you so much for sharing this
It's boring when we have to "get by" but at least we gain knowledge and practice without

depending on others.

 

Really you cannot identify the differences?

This only confirms that you have done your job carefully and perfectly!

 

Congratulations on BELIEVE IN YOUR OWN!

Your comment only serves me as an encouragement, and one of the good ones!



#13 ngc7319_20

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Posted 19 August 2019 - 10:15 PM

Is that a small set screw near the lens?  Are there more screws? What happens is these are removed?  Does the metal part holding the lens turn off?

 

post-292205-0-13097300-1566266415 x.jpg

 

Does it separate where I have marked in red?

 

post-292205-0-00683300-1566266385 2x.jpg


Edited by ngc7319_20, 19 August 2019 - 10:21 PM.



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