Nikon EII general question- Zeiss or B&L framed bino? (1 Viewer)

[pat mitchel]

Since I have never had one in my hands, can someone enlighten me as to the design construction- are the prisms on a detachable tray as in Bausch and Lomb (American pattern) frames or is it a Zeiss frame with the prism dropped into slots milled in the bino frame a la German pattern binos. With the forward prism plates, that would tend to mean that it is a Zeiss framed bino where the forward prisms are removed via removal of the forward prism body cover plates. If so, what is the common method of prism adjust to affect optical alignment. I assume they use eccentrics on the objectives which are commonly used to affect small changes (which if the body is properly machined may be all that's needed to finalize the alignment), but a larger change would typically be made with tilt screws to the prisms or literally moving the prism in a slightly longer than needed slot with grub screw adjusts. Anyone "been under the hood" of an EII? Thanks and regards, Pat

 

[William Lewis]

Does this help? I think it's from allbino's. To me it looks like the body does most of the work of holding the prism which would tally with the early "e" series binoculars being close to the Zeiss design and later iterations following on?

 

[William Lewis]

Hopefully John or Henry will be along shortly with some more useful information!

 

[pat mitchel]

William Lewis- it absolutely answers the question, it is indeed a Zeiss framed bino (German pattern) and it does not appear to have any means other than eccentrics on the objective to adjust alignment so the machining has to be done precisely. A well made yet classic build. Thanks for digging up the xray pic. Much appreciated as I only have a a series A nikon 8x30 and that while a bit dim (coatings have had a HARD life) is useful and sharp- at least it cleans easily thanks to the accurate machining, the prisms are precisely positioned making cleaning/ resetting a simple matter. Regards, Pat

 

[tenex]

Is the objective focal length really so short here that the forward prism isn't obstructing the light path? I haven't thought about the construction of stubby Porros before.

 

[henry link]

Is the objective focal length really so short here that the forward prism isn't obstructing the light path? I haven't thought about the construction of stubby Porros before.

The E and EIIs have a very compact prism cluster. The photo below shows the two prisms from an 8x30 E, but all the other Es and EIIs have the same prisms. The As are probably the same too.

You can see that the larger "front" prism is asymmetrical so that it's larger on the side that accepts the light cone directly from the objective lens and smaller on the side that passes on the shrinking light cone to the small "back" prism. There's no obstruction of the objective lens' aperture even though its focal length is very short, a little less than 110mm.

BTW, The edge blackening of the small prism was done by me, the binoculars don't come that way.

Pat,

You're right, there are no adjustments for prism tilt. The eccentric objective cells are all there is for collimation.

Henry

 

[tenex]

You can see that the larger "front" prism is asymmetrical so that it's larger on the side that accepts the light cone directly from the objective lens and smaller on the side that passes on the shrinking light cone to the small "back" prism. There's no obstruction of the objective lens' aperture even though its focal length is very short, a little less than 110mm.

So a short focal length (combined with prism asymmetry) does avoid obstruction... but even 110mm seems like too much here. Am I missing something?

 

[normjackson]

So a short focal length (combined with prism asymmetry) does avoid obstruction... but even 110mm seems like too much here. Am I missing something?
View attachment 1579227

A 3D view?

 

[William Lewis]

What you see in the X ray looks like this Eric -
But it's misleading as the face the light enters into of the second prism is, as Norm suggests, actually above the first face the light enters of the first prism.

Like this -

Without the 90° bend, the image remains both upside down and mirror flipped left to right.

So with the prisms in a line like this -

The view through looks like this -

 

[John A Roberts]

Hi Norm (post #8),

That was also my thought. As an example, a diagram from Frank of the SarD 6x42’s optics perhaps helps to make things clearer:

https://flic.kr/p/a1Kfwv

John

 

[tenex]

A 3D view?

Exactly. Duh. Thanks.

Who made William's cute red monocular, and is it the usual 8x21?

 

[William Lewis]

It's a Russian job, quite a nifty little thing, 5x25 so a half decent 5mm exit pupil and good depth of field. You can get an idea of the view through from the photo above though, it's not terrible but I wouldn't go looking too closely! Bit little and large with the dob?

 

[Binastro]

Also made in 7x25 and different colours.

My 5x25 is rather poorly hand painted and unfortunately opens up more than it should, so I had to mark the correct position.

The typical 8x21 folding monoculars open correctly with a proper stop.

Regards,
B.

 

[William Lewis]

It collects 1.5% of the light the dob does. Horses for courses.

 

[Patudo]

The edge blackening of the small prism was done by me, the binoculars don't come that way.

I'd be interested to know if you think it makes a difference. If so, it'd be a surprising omission by Nikon (and others).

 

[henry link]

I'd be interested to know if you think it makes a difference.

That experiment was thirty years ago. All I recall is being underwhelmed by the result. That particular 8x30 E was later dropped causing a prism to chip. It became a parts binocular after that which is why I still have the raw prisms in the photo.

 

[pat mitchel]

Perhaps the edge blackening has more to do with the earlier and largely uncoated surfaces and the cumulative loss of throughput. A small gain in brightness might be perceived from the low starting point. With the higher transmission nature of the improved coatings, the eye can't perceive the smaller gain?

 

[Patudo]

But with porro prisms there should be total internal reflection?

PS.

Zeiss framed bino where the forward prisms are removed via removal of the forward prism body cover plates.

IIRC that is true of the classic Zeiss porros, but it might be worth noting that at least some of the later models from Zeiss West eg the 8x50/8x50B went to a one-piece body, I suppose because of better resistance against shock. It'd be real interesting to get the professionals' take on those.

 

[Obserwatorek]

My orginal X-Ray, not degraded by Allbinos ...

 

[agus_m]

My orginal X-Ray, not degraded by Allbinos ...

Very nice, do you have more of these xray images posted somewhere? I am curious to see other bino designs, it should be easier to do xray images rather than make binocular cutaways.