Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

DELAMINATER OBJECTIVE How to repair

Binoculars Classic DIY Eyepieces Optics Refractor
  • Please log in to reply
15 replies to this topic

#1 LU1AR

LU1AR

    Vostok 1

  • -----
  • topic starter
  • Posts: 181
  • Joined: 04 Mar 2020

Posted 08 May 2021 - 09:27 PM

I acquired -for coins- a Japanese Zenith binocular, broken and unrecoverable. It was to fix another one that had a broken bridge - which I also bought for coins - which was in good condition but with a broken bridge, which is made of sintered metal.
So I was left with a binocular, just for spare parts.
Now, I am doing a 4X50 finder for a large telescope. For that, I decided to recover one of the lens that was badly damaged. I thought they were just fungus, but the Canada Balsam glue that maintains the optical continuity of the achromatic doublet was delaminated.
So I go on to reveal some closely guarded secrets:
TO TAKE OFF THE LENSES: There is a thin lens and a fat one, glued together. We put them in a jug with water and we send it to the fire. We wait for it to boil and leave it boiling for 10 or 15 minutes. Then, we empty the water on a mesh cloth in the sink; we grab the doublet with a dry cloth and struggle to both sides to displace them.
The Canada Balsam became sticky and slowly, the lenses are separating. It is not necessary to mark them, because the concavity of the fat lens (Flint) fits exactly into that of the thin lens (Crown) facing forward.
Then, with a cloth soaked in solvent (Thinner, Turpentine, Kerosene, or Lighter Fluid), we clean the gum left by the Balsam of Canada.
Next, we clean well with Windex, which is used by observatories around the world. These cleaners have a detergent, so the final cleaning is with a Karilina tissue (Neutral. Unscented) and some breath.
Finally, we place the Flint (thick glass) down and after verifying that part of the Crown goes forward, we put a DROP OF OIL and close both lenses. We move with our fingers (It gets dirty, but only the outer part of the doublet which is then cleaned) and we wait for the droplet to be distributed throughout the joint. They already stick together. If we put too much oil, we clean the edge before putting the doublet in the cell and screwing it in.
More SECRETS: Before assembling the doublet, I paint the edge of the glass with black fiber. I did the test with an unpainted one and the contrast improvement is remarkable. I also do this with the eyepieces.
I use oil of any kind. Johnson Baby Oil, Olive cooking or engine oil, was perfect.
I hope this helps someone.
Regards.
Edgardo.

Attached Thumbnails

  • Lente Zenith 7X50 01.jpg
  • Lente Zenith 7X50 03.jpg

  • WWTech, j.gardavsky and ECP M42 like this

#2 Rokkor

Rokkor

    Vostok 1

  • -----
  • Posts: 105
  • Joined: 19 Dec 2019

Posted 09 May 2021 - 05:37 AM

Engine oil? Well I suppose one of these ubiquitous 'Zenith' binoculars doesn't deserve much better, but I am surprised none-the-less. lol.gif

But what was the point of using any oil at all - why not just leave them dry? 


  • LU1AR likes this

#3 ECP M42

ECP M42

    Ranger 4

  • -----
  • Posts: 321
  • Joined: 28 Apr 2021
  • Loc: central Europe 45°N

Posted 10 May 2021 - 03:57 AM

I imagine leaving it dry could worsen chromatic aberrations and produce deleterious reflections. Glued achromats are produced for these reasons. An achromatic doublet designed for glue should not be joined in air.

 

But it is funny to read that someone also uses motor oil, when one could use the oil, certainly more suitable, for microscopy.

 

Edgardo, have you tried sea fat?

 

Good job!


Edited by ECP M42, 10 May 2021 - 03:59 AM.

  • Rokkor and LU1AR like this

#4 LU1AR

LU1AR

    Vostok 1

  • -----
  • topic starter
  • Posts: 181
  • Joined: 04 Mar 2020

Posted 11 May 2021 - 04:35 PM

Engine oil? Well I suppose one of these ubiquitous 'Zenith' binoculars doesn't deserve much better, but I am surprised none-the-less. lol.gif

But what was the point of using any oil at all - why not just leave them dry? 

 

 

I imagine leaving it dry could worsen chromatic aberrations and produce deleterious reflections. Glued achromats are produced for these reasons. An achromatic doublet designed for glue should not be joined in air.

 

But it is funny to read that someone also uses motor oil, when one could use the oil, certainly more suitable, for microscopy.

 

Edgardo, have you tried sea fat?

 

Good job!

 


Zenith binoculars are an intermediate quality brand, made in Japan in the 60's. They are generic and interchangeable with several others, such as Hoya or Tasco. The kind of binoculars you can carry -without fear- under the seat of your car.
They are very cheap in the used market, but even having been stored, time has degraded them. But they are a good source for making finders, and guide telescopes.
Prisms are great for doing other projects. Right now I am making a Herschel wedge with a one, from a japan binocular.
Having used olive oil or Johnson baby oil is proof of concept, and also a source of entertainment at this pandemic times. With businesses closed it is impossible to acquire specialized products.
Many people get scared trying to get their hands on these optical parts, and binos are a good source of fun. In fact, the lenses I showed made both excellent finders.
The attached photo is another project that I am carrying out, to improve a cheap refractor (90X900) masked at 70 mm / F13 specially adapted for solar use.
Herschell's wedge saw light today and detected two tiny spots in the sun in my company's parking lot. They used one of the prism.
Many people prefer to buy things by mail and I enjoy these amateur projects.
Thank you for your comment.
Regards.
Edgardo


 

Attached Thumbnails

  • Prisma de Herschell 06.jpg

Edited by LU1AR, 11 May 2021 - 04:37 PM.

  • Rokkor and ECP M42 like this

#5 ECP M42

ECP M42

    Ranger 4

  • -----
  • Posts: 321
  • Joined: 28 Apr 2021
  • Loc: central Europe 45°N

Posted 11 May 2021 - 04:46 PM

Excellent work, I see you enjoy yourself too waytogo.gif  


  • LU1AR likes this

#6 Rokkor

Rokkor

    Vostok 1

  • -----
  • Posts: 105
  • Joined: 19 Dec 2019

Posted 12 May 2021 - 12:18 PM

I applaud the ingenuity and creativeness. It's much better than sending either to the rubbish bin. Certainly the prisms are probably a finer quality than the objective or the eyepiece. Is it possible to make a magnifier loupe out of the eyepiece, maybe? You could put it on a keychain if it is useful, and you didn't already own one. 


  • LU1AR likes this

#7 DAVIDG

DAVIDG

    Voyager 1

  • *****
  • Posts: 10,239
  • Joined: 02 Dec 2004
  • Loc: Hockessin, De

Posted 12 May 2021 - 12:30 PM

 I have done it many times. Here is my thread on how it is done. By the way I have also "oiled" many objective that were once cemented. I use medical grade mineral oil. The stuff is sold as a laxative in drug store. 

 

                - Dave 

 

https://www.cloudyni...cement-a-lens/ 


  • wrnchhead and LU1AR like this

#8 semlin

semlin

    Mariner 2

  • -----
  • Posts: 229
  • Joined: 20 Jul 2009

Posted 12 May 2021 - 02:04 PM

fantastic thread.  i love the idea of using oil instead of cement since i am quite fearful of messing up the spreading of the cement.

 

i have an old herter's child's spotting scope i got as a bycatch in an auction with failed glue in the doublet objective.  it looks like the one below.  

 

so i can try this with no fear of a bad outcome!

 

s-l400.jpg


  • LU1AR and ECP M42 like this

#9 DAVIDG

DAVIDG

    Voyager 1

  • *****
  • Posts: 10,239
  • Joined: 02 Dec 2004
  • Loc: Hockessin, De

Posted 12 May 2021 - 02:39 PM

 As my thread shows,  you can  use UV curable cement  and there is no problem in   spreading the cement and get things right before you activate it to set the pieces in place. If you do use an "oil" you should use one that is chemically and biologically inert. Motor oil and vegetable oils can oxidize over time  and yellow  or grow bugs  You also want one that has a  high viscosity or it can leak out over time. especially if the lens is thermally cycled from hot to cold. The best material I found to oil an objective is very high molecular weight polysiloxane.  The material I use is as thick as honey, is water clear and the refractive index is close match to optical glass.  The next best is medical grade mineral oil.

   Here is a picture of my bottle of polysiloxane. Note how you can not see the interface between the material and the glass because of the good match in refractive index between the two materials.

 

                   - Dave 

 

polysiloxane.jpg


Edited by DAVIDG, 12 May 2021 - 06:25 PM.

  • semlin, j.gardavsky and LU1AR like this

#10 ECP M42

ECP M42

    Ranger 4

  • -----
  • Posts: 321
  • Joined: 28 Apr 2021
  • Loc: central Europe 45°N

Posted 12 May 2021 - 05:20 PM

Great works, Dave. Oil, amber, glue ... so on and so forth! waytogo.gif

 

Hi Rokkor,

Is it possible to make a magnifier loupe out of the eyepiece, maybe?

Of course it is possible. Inside you will find various groups of various powers and utilities. But generally the lenses of binocular eyepieces have a bit narrower diameters. Perhaps more comfortable for the keychain, but not comfortable for reading.

 

 

PS: Excuse me, but for me it's really funny to read about "cemento" grin.gif

The term "cement" is incorrect when used instead of the term "glue", although many use it for that purpose, without knowing it.

Cement is not used to glue doublets or other lenses and prisms together, but amber (Balsam of Canada) or modern epoxy glues are used. And it is more correctly said "glued doublet" from the term glue, and not "cemented doublet" (which sounds scratchy). Cement (useful for opus caementicium) is a fine calcium powder that scratches glass. Cement is used to cement the prisms to the frame, to prevent them from moving from their seats and remaining collimated.


Edited by ECP M42, 12 May 2021 - 05:21 PM.


#11 j.gardavsky

j.gardavsky

    Mercury-Atlas

  • *****
  • Posts: 2,809
  • Joined: 18 Sep 2019
  • Loc: Germany

Posted 13 May 2021 - 07:57 AM

Great works, Dave. Oil, amber, glue ... so on and so forth! waytogo.gif

 

Hi Rokkor,

Of course it is possible. Inside you will find various groups of various powers and utilities. But generally the lenses of binocular eyepieces have a bit narrower diameters. Perhaps more comfortable for the keychain, but not comfortable for reading.

 

 

PS: Excuse me, but for me it's really funny to read about "cemento" grin.gif

The term "cement" is incorrect when used instead of the term "glue", although many use it for that purpose, without knowing it.

Cement is not used to glue doublets or other lenses and prisms together, but amber (Balsam of Canada) or modern epoxy glues are used. And it is more correctly said "glued doublet" from the term glue, and not "cemented doublet" (which sounds scratchy). Cement (useful for opus caementicium) is a fine calcium powder that scratches glass. Cement is used to cement the prisms to the frame, to prevent them from moving from their seats and remaining collimated.

Where did you read it?

 

Here is a list of the cements for bonding the optics:

https://www.optical-...ents/chart.html

 

Besides the old Tele Vue Plössls, you will hardly find any new Tele Vue eyepiece having lenses bonded with Canada Balsam.

Among the modern high performance eyepieces, the Canada Balsam as the bond material has been used again in the BCO Abbes.

 

Thank you for the chuckle,

JG
 



#12 MartinPond

MartinPond

    Fly Me to the Moon

  • *****
  • Posts: 6,240
  • Joined: 16 Sep 2014

Posted 14 May 2021 - 01:06 AM

 As my thread shows,  you can  use UV curable cement  and there is no problem in   spreading the cement and get things right before you activate it to set the pieces in place. If you do use an "oil" you should use one that is chemically and biologically inert. Motor oil and vegetable oils can oxidize over time  and yellow  or grow bugs  You also want one that has a  high viscosity or it can leak out over time. especially if the lens is thermally cycled from hot to cold. The best material I found to oil an objective is very high molecular weight polysiloxane.  The material I use is as thick as honey, is water clear and the refractive index is close match to optical glass.  The next best is medical grade mineral oil.

   Here is a picture of my bottle of polysiloxane. Note how you can not see the interface between the material and the glass because of the good match in refractive index between the two materials.

 

                   - Dave 

 

attachicon.gifpolysiloxane.jpg

 

Polysiloxane.....clear, thick silicone oil...brilliant!

 

UV-cured resin is OK too, but the siloxane seems more low-hassle.

 

When stripping badly crusted canada balsam from old opera glasses,

I make sure to do a good acetone soak and scrubbing.  Putting the parts

back together dry is much clearer...but definitely lower contrast. Better with something to

  fill the void.

 

 

Canada balsam rarely crazes up from age...it's usually an overheating at some point,

   like putting the binocs down on a sun-heated porch rail.


  • LU1AR and ECP M42 like this

#13 MartinPond

MartinPond

    Fly Me to the Moon

  • *****
  • Posts: 6,240
  • Joined: 16 Sep 2014

Posted 14 May 2021 - 01:12 AM

 

Zenith binoculars are an intermediate quality brand, made in Japan in the 60's. They are generic and interchangeable with several others, such as Hoya or Tasco. The kind of binoculars you can carry -without fear- under the seat of your car.

....

....

 

 

Excellent review of Zenith!  Good , solid,  medium-grade stuff.

Very good for the price, usually.

 

The "Super Zenith" binocs are usually not as good as the Zenith, BTW.

Like other dud models, like....Bushnell Ensign, or Swift Aerolite,

 or more recently Bushnell Falcon (a lot of uncoated parts inside).

 

So...yeah Zenith = pretty good.


  • LU1AR likes this

#14 pat in los angeles basin

pat in los angeles basin

    Viking 1

  • *****
  • Posts: 836
  • Joined: 20 Nov 2015

Posted 14 May 2021 - 08:58 AM

Martin; I got a only bid 7x35 10deg aerolite and the thing (despite the slightly dim-thanks to the amber coating objectives)  is sharp, mechanically accurate focuser and decent build quality. BK-7 of course. A keeper .   Regards, Pat



#15 MartinPond

MartinPond

    Fly Me to the Moon

  • *****
  • Posts: 6,240
  • Joined: 16 Sep 2014

Posted 14 May 2021 - 11:05 AM

I had a messy, crooked  10x50 aerolite,

but I haven't seen the 7x35//10-deg. 

The 2-3 main makers of that combination did a good job.

Is there a JB number?

 

There are a few good Ensigns, too.....quality does vary.



#16 pat in los angeles basin

pat in los angeles basin

    Viking 1

  • *****
  • Posts: 836
  • Joined: 20 Nov 2015

Posted 14 May 2021 - 11:53 AM

the aerolite is JB256, no JE#'s. I also scored an almer coe (that famous american company??) with simple 3 element EP's for a buck! (plus shpg of 12).  Another 10 deg bino with good image, good focuser-JB194,JE3. Can't recall the #  of elements in the EP of that- close to the good king korn country wide bino's.  Regards, Pat




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics





Also tagged with one or more of these keywords: Binoculars, Classic, DIY, Eyepieces, Optics, Refractor



Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics