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Optical Construction of HG/ LX and EDG Binoculars (1 Viewer)

John A Roberts

Well-known member
For ease of future reference, I’ve posted in this new thread information with additions,
that I posted yesterday (in a Leica thread!) about the the Nikon HG/ LX and EDG series:

It’s commonly thought that the premium Nikon roof prism binoculars have unique optical designs

This is because:
- the cross-section views seem to show the use of fewer but thicker elements than in other premium designs, and
- Nikon does not state the number of lenses in their binoculars

However, cut away images (showing the external shapes of the lenses) show more detail
and that somewhat disappointingly the binoculars are very conventional designs

In order:
A) HG - showing only groups
B) HG - lenses and groups
C) HGL - lenses and groups (i.e. the light weight version of the HG, with the same optical construction, though using lead and arsenic free 'Eco' glass)
D) EDG - showing only groups

n.b. A), B) and C) are all specifically the 8x42 versions (as indicated in the images)

As can be seen the HG/ HGL construction is:
Objective 4 lenses in 3 groups (2, 1 + 1 focusing); Eyepiece 6 lenses in 4 groups (1, 2, 2, 1)

And the EDG construction is:
Objective 4 lenses in 3 groups (1, 2 + 1 focusing); Eyepiece 6 lenses in 4 groups (1, 2, 2, 1)

So notably there is a reordering of the objective construction
The EDG focusing lens is of significantly larger diameter than that of the HG (and the EDG body has been modified to enable this)
And most likely other details of the lenses (thickness, curvature, composition and spacing) differ between the two lines



  • HG 8x42 - cross section.jpg
    HG 8x42 - cross section.jpg
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  • HG 8x42 - showing lenses.jpg
    HG 8x42 - showing lenses.jpg
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  • HGL 8x42 - with lenses.jpg
    HGL 8x42 - with lenses.jpg
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  • EDG - cross section.jpg
    EDG - cross section.jpg
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Last edited:
I’ve posted some images comparing the original version of the EDG (with twin bridges like the Swarovski EL SV),
and the later modified version (with a larger single bridge like the Swarovski SLC)
The images clearly show that the focusing mechanisms differ

In addition, the image of the original EDG shows an eyepiece of simplier construction with 5 lenses in 3 groups (2, 2, 1)
So most likely the 7x42 version

See at: https://www.birdforum.net/threads/nikon-edg-7x42-floating-diopter-question.403642/#post-4137382

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