[Tech] Are most/all roof binocular oculars and objectives collinear? (1 Viewer)

[eronald]

Hi -

My Zeiss Pocket and my Ultravid x42 both seem to have collinear oculars and objectives, or at least the casings appear collinear (cylinders strung on the same line) .

I wonder whether all usual roof binoculars have collinear oculars and objectives, whether this is a necessity or just a usual design decision?

Porros of course have an offset between objectives and eyepieces by design.

Edmund

 

[Troubador]

Hi Edmund, my experience is that all roof binos using Schmidt-Pechan prisms have objectives and oculars on the same optical axis but those with Abbe-Koenig prisms may have a slight offset of the oculars depending on how the prisms are arranged. So my HT 8x42s had this offset.

Lee

 

[henry link]

At least a few Schmidt-Pechan roof prism binoculars have a slight offset. The 42mm Swarovski NL Pure objective lens baseline is about 4-6mm wider than the eyepiece baseline (depending on the IPD setting) and I recall measuring an old Nikon 8x32 HG-L with objectives set slightly inboard of the eyepieces. There are probably others with small offsets that go unnoticed in normal use.

 

[eronald]

At least a few Schmidt-Pechan roof prism binoculars have a slight offset. The 42mm Swarovski NL Pure objective lens baseline is about 4-6mm wider than the eyepiece baseline (depending on the IPD setting) and I recall measuring an old Nikon 8x32 HG-L with objectives set slightly inboard of the eyepieces. There are probably others with small offsets that go unnoticed in normal use.

Ah, that’s interesting! I noticed that the NL misses my IPD by a hair, and I wondered why they didn’t let it fold a bit more …but I completely missed the offset. The strange thing is the x32 NL do my IPD, when I look throught them, and I thought maybe Swaro thinks the 1mm added pupil size on the x42 versions compensates for the lack of eye placement

BTW, is there a list of the measurements of various bins somewhere? I’m interested in the outside objective barrel and outside eyecup barrel diameters at the moment …

Edmund

 

[John A Roberts]

To help illustrate Henry’s observation that S-P prisms can have a slight degree of light axis offset, see some examples where the light path is clearly indicated.

Firstly with no offset:
A) Zeiss Dialyt 8x30B
B) Leica Ultravid 8x42 (from a 2016 eBay listing by leica-store-lisse)

And with a slight degree of offset:
A) Swarovski SLC 7x50 (from a 2015 eBay listing by canadiansportsoptics)
B) Swarovski EL SV x42 (from a 2018 visit by Park Cameras to the Swarovski factory at: Exploring The Home of Swarovski Optik | Blog | Park Cameras )


In relation to the Swarovski NL, when it was introduced it was noted that the prisms were rotated 90 degrees around their optical axis, see the last paragraph in the extract:

Below is . . . from the Fieldsports News post at: Swarovski bets on field of view with NL Pure hunting binoculars
. . .

Swarovski bets on field of view with NL Pure binos
June 30, 2020

Forget light transmission, forget ease-of-use – they are last year’s optic USPs. Swarovski’s three new binocular launches pushes a new boundary: it’s all about field of view.

With its NL Pure, launched on 1 July 2020, Swarovski wants to immerse you in your view by offering a market-leading 71-degree ‘apparent’ field of view.
No detail on why the use of the word ‘apparent’ but the new binos are a lens system the same as the Swarovski EL, so it is not digital manipulation.

“In the past, we have talked about edge-to-edge sharpness,” says Swarovski spokesman Wolfgang Schwarz. “But there is one thing that’s even better – no edges at all.”

The 8×42 NL Pure field of view is 159 metres at 1,000 metres. The 10×42 offers 20% more field of view that the Swarovski EL 8×42. And, for the first time, Swarovski is offering a 12×42,
an NL Pure that has a field of view with 130 metres at 1,000 metres that beats the EL 10×42’s 112 metres at 1,000 metres.

And did we say forget light transmission, forget ease of use? Forget that. Handling is still a thing. By rotating the prisms to right angles, Swarovski has slimmed down the middle of the tubes.
That helps the NL Pure fit your hands more easily.
. . .

And also see an image illustrating how the prism rotation enables the distinct pinched waist of the NL x42. It makes use of an x-ray photograph from mnich at: Optical construction of Swarovski NL Pure binoculars - AllBinos.com
So if the NL x42 uses the same prisms as the EL SV x42, the degree of side-to-side offset (the objective spacing) may be different than that of the EL SV (?)


John

 

[Tringa45]

Here are a few measurements:-

Kowa 33 mm Genesis and Swarovski 30 mm CL2 have coaxial objectives and eyepieces.
At my 63 mm IPD the objectiv spacing differed by the following amounts:-
Swarovski 7x42 SLC, 2 mm
Swarovski 10x42 mm EL SV, 5 mm
Meopta 7x42 B1, 6 mm
Swarovski 8x56 SLC (current version) 15 mm

Both Schmidt-Pechan and Abbe-König prisms can be constructed with or without offset.
The barrels of the 56 mm SLC above are 64 mm in diameter, so an offset is mandatory if one wants to achieve an IPD of less than 64 mm.
Even the barrels of binoculars with 42 mm objectives are around 54 mm, so probably for aesthetic reasons or if the designers wish to avoid barrel contact at minimum IPD, most of them have some offset.
Abbe-König prisms with total internal reflection can enable small gains in transmission but, since the demise of the Zeiss FLs and HTs, are no longer found in 42 mm bins. This is probably because they take up a lot of space. If a prism demands an aperture of "w" the length of an S-P prism, according to Holger Merlitz, is 1,21w and that of an A-K prism 3,46w.
Funny though that on the really long SFs, Zeiss decided on the minor optical compromise of S-P prisms in the interests of weight balance.

John

 

[dorubird]

Also few measurements from me:
I measured a difference of 2mm in favor of the distance between the eyepieces vs front lenses distance at Nikon HGL 8x32 (as henry link measured. Very atypical for a roof reminding me of a reverse porro).
I measured a difference of 1mm in favor of the distance between the front lenses vs eyepieces distance at Zeiss Victory P 8x25.
I measured a difference of 6mm in favor of the distance between the front lenses vs eyepieces distance at Zeiss Victory SF 10x42. (this is also an explanation for why I notice a more pronounced streoscopy on this SF roof binoculars)

 

[Maljunulo]

I need someone to educate me on the difference between "collinear" and "coaxial", which is the word my mind keeps insisting on.

 

[Canip]

Coaxial vs Collinear - What's the difference?

As adjectives the difference between coaxial and collinear is that coaxial is (geometry) having a common central axis while collinear is...

wikidiff.com

So I assume the right term here would be collinear

 

[Maljunulo]

Coaxial vs Collinear - What's the difference?

As adjectives the difference between coaxial and collinear is that coaxial is (geometry) having a common central axis while collinear is...

wikidiff.com

So I assume the right term here would be collinear

Very nice, except that the definition for collinear includes coaxial.

Almost as if they were synonyms, but I know they are not

 

[Troubador]

Coaxial vs Collinear - What's the difference?

As adjectives the difference between coaxial and collinear is that coaxial is (geometry) having a common central axis while collinear is...

wikidiff.com

So I assume the right term here would be collinear

Not so fast Pinac! Coaxial is given as an alternative word to collinear so it appears these words are inter-changeable although I have only seen coaxial used when referring to two electric cables, one wrapped around the other and both inside an outer insulation.

Lee

 

[Tringa45]

Isn't collinear a two dimensional description, whereas coaxial is three dimensional?
The parallel eyepiece and objective axes of one porro barrel cold be described as collinear if viewed from a certain angle.

John

 

[Maljunulo]

My idea is that if the optical centers of two or more lenses lie on the same axis (perpendicular to their surfaces) those lenses are correctly described as coaxial, irrespective of where on that axis they lie.

I must admit to still being somewhat confused by the word "collinear".

 

[ZDHart]

My impression (which could be totally wrong!) is that coaxial implies two objects sharing the same central axis - as a tweeter placed in the center of a woofer in speaker design, or an electrical wire with a central lead at the core and an outer braid lead surrounding that same central core.

It seems to me that perhaps collinear would refer to two objects, like the two barrels of binoculars, each having their own axis, but those two axis being near perfectly aligned linearly (parallel) with each other. And perhaps the two axles of a vehicle may also be collinear?

I'm sure an expert will chime in to confirm or correct.

 

[Tringa45]

And perhaps the two axles of a vehicle may also be collinear.

No, only parallel on level ground. The wheels would only be perpendicular to the axle on a driven rear solid axle.
Otherwise there is usually some camber (+ve. or -ve.) and some toe-in or toe-out.

John

 

[WJC]

Much adu about nothing. Engineers don’t care; birds don’t care. The winner is ……… all who have participated! Such thinkery could NEVER happen on Facebook. There, correct English is being slaughtered as we speak!

 

[eronald]

My impression (which could be wrong!) is that coaxial implies two objects sharing the same central axis - as a tweeter placed in the center of a woofer in speaker design, or an electrical wire with a central lead at the core and an outer braid lead surrounding that same central core.

It seems to me that collinear would refer to two objects, like the two barrels of binoculars, each having their own axis, but those two axis being near perfectly aligned linearly (parallel) with each other. And perhaps the two axles of a vehicle may also be collinear.

I'm sure an expert will chime in to confirm or correct.

O Master I bow before thy wisdom and heed thy Word!
Thank you for setting me right!

Edmund

 

[ZDHart]

O Master I bow before thy wisdom and heed thy Word!
Thank you for setting me right!

Edmund

? I'm certainly no master - just speculating as to my impressions of the meanings of the two terms, with reference to Maljunulo's post #8.

In other news... Edmund, I love your sketches, as you call them - they're fantastic.

 

[eronald]

? I'm certainly no master - just speculating as to my impressions of the meanings of the two terms, with reference to Maljunulo's post #8.

In other news... Edmund, I love your sketches, as you call them - they're fantastic.

Your advice concerning the use of "collinear and coaxial" is perfectly correct - when I wrote the post I was looking for the right word and grabbed the wrong one

Thank you for the compliments re. my sketches! I always enjoy having viewers - artists are by nature exhibitionists

Edmund

 

[ZDHart]

Your advice concerning the use of "collinear and coaxial" is perfectly correct - when I wrote the post I was looking for the right word and grabbed the wrong one

Thank you for the compliments re. my sketches! I always enjoy having viewers - artists are by nature exhibitionists

Edmund

Edmond... I think your artwork is fabulous and highly creative. Quite worthy of being displayed and appreciated far and wide! True art, indeed, and just very cool, I'd say!

Some of my favorites:

At the Opera?
Minifig
Old friends at dinner
Portrait of a Man with Beard
Luxembourg Garden couple
Thoughtful Bird
Waiting for Godot
Elizabeth
Bigbeak Monstah’bird
Subway Sleeper
Painted in a train from the Riviera to Paris (côte d’azur)
Orange outside, free inside
Near Monceau a month or two ago

Reminds me a bit of Hillary Knight's work. Very inspiring.