Nikon Aculon A211 12x50 lost lens. (1 Viewer)

[jaculek]

HI everyone,my name is Jacek, i am from Poland,
I have Nikon Aculon A211 12x50 binoculars. The binoculars have been through a lot, the right eyepiece is missing the central flat-convex lens.
This missing, central lens has a diameter of 22mm, a thickness of 4.5mm in the middle and a thickness of 2.5mm at the edge.
I wrote that it is a flat-convex lens, although it is also a bit convex on this flat side.
Can I get such a lens somewhere? Nikon service told me that they do not sell such parts, only repair. Cost of repair almost like new binoculers.

 

[Binastro]

Hi and welcome.

You need to measure the curves.
An optician could do this for you, maybe free .
Also the focal length of the lens.

You need to know the glass type also, but an optician may be able to tell you.

If you had a spherometer you could measure the curves yourself.

It may be coated, but it won't matter much if you got an uncoated lens element.

You could look at Edmunds Scientific in the U.S. for a replacement, but an optician can get you one made by his lab, although the blanks they usually use are larger for glasses.
If it is an unusual glass type the optician may not be able to help you.

As I think opticians probably charge less where you live it might be cost effective.

The front eyepiece field lenses maybe aspheric on your binocular, but this lens may have simple curves.

If you cannot get this done then you need to buy a replacement binocular or buy a secondhand similar binocular maybe in not so good condition cheaply and take the lens element from that.
A broken binocular would be ideal.

Generally the Aculons are not repaired just replaced as I think some parts are just glued.

I don't know if the patent specifies the glass type for this element.

Good luck.

Regards,
B.

 

[jaculek]

Thank you very much for your answer.
I will indeed try an optician.
As you wrote, it's best to find another broken pair of binoculars.
Regards.

 

[Binastro]

The problem may be identifying the glass type.

It may be a simple well known type, but maybe not.

Regards,
B.

 

[jaculek]

I used acrylic lenses from an old plastic binocular and it even works, but the diameter is larger and the sleeve does not screw in all the way and the magnification is smaller. The front lens is made of two glued lenses (achromat doublet).
Regards.

 

[Binastro]

The achromatic doublet is cemented or balsamed together.

The glue I think is the way the binocular is assembled.

The following are options.

1. Buy a new Aculon 12x50.

2. Buy a very good little used secondhand Aculon 12x50 for normal use, keeping the old one for spares.

3. Buy a very poor secondhand Aculon 12x50 and either take a whole eyepiece and put that in your existing 12x50, or take the replacement eyepiece apart and use the one replacement element.

4. The problem with the optician is that he or she can measure the refractive index of the single element, but this is not the whole specification and also he or she may not be able to get the correct glass blank to have his lab work on.

Also when reassembling the spacing and position of the elements has to be correct, with no tilt.

Using an incorrect glass type you can get the right magnification but the aberrations will not be properly corrected.

Regards,
B.

 

[jaculek]

Thank you for the advice, I will probably choose the third option. I will look for it, regards.