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New Horizons II (1 Viewer)
- Thread starter Omid
- Start date
WJC
Well-known member
Now, Peter,
You’re TRYING to get me spun up, aren’t you?!
I remember the first time I ever worked on a Bushnell Ensign and realized my cotton swab was STUCK to the field lens! ‘Said to myself:
“Self, I’ll bet that sucker has a plastic field lens. And being the brilliant sort I am, I answered me ... sure ‘nuff." :cat:
Bill
Foss
Well-known member
Here's my two cents to one possible future of binoculars (Inspired by a recent trip to the dentist wherein they computer imaged my right rear molar set, ground-down the offending cracked tooth, and used 3-D printing to create a 100% match of the old molar. I was out the door in < 90 minutes. Maybe it's the novocaine talking but....
A customer walks into an optomotrist-like office and gets eyes 3-D mapped...down to the smallest detail, rods, cones, astigmatism, pupil dilation, everything. Based on that information, expected usage, personal preferences, and credit card limit, a binocular body and perfectly tailored optical train are selected.
A few weeks later, the UPS truck delivers the most amazing binoculars this individual will ever look through.
A customer walks into an optomotrist-like office and gets eyes 3-D mapped...down to the smallest detail, rods, cones, astigmatism, pupil dilation, everything. Based on that information, expected usage, personal preferences, and credit card limit, a binocular body and perfectly tailored optical train are selected.
A few weeks later, the UPS truck delivers the most amazing binoculars this individual will ever look through.
Bill, my comment was based on the understanding that some top end optics have fibre reinforced polymer housings... not yer $1 kiddie bins with PS (BS!) lenses.
Wizzy wizzy, 3D..... cool looking pictures, the proof is on the accuracy with which the scans and resulting production processes operate. For instance x-ray Volumetric images are cool, but there’s still work to do before you get accurate high precision measurements from it....
I once worked with colleagues on a refractive index mapping project.. got a paper with me name on too. It’s a lot harder than you think. As we know eyes change and so I’d prefer to change glasses than custom binoculars.
PEter
Wizzy wizzy, 3D..... cool looking pictures, the proof is on the accuracy with which the scans and resulting production processes operate. For instance x-ray Volumetric images are cool, but there’s still work to do before you get accurate high precision measurements from it....
I once worked with colleagues on a refractive index mapping project.. got a paper with me name on too. It’s a lot harder than you think. As we know eyes change and so I’d prefer to change glasses than custom binoculars.
PEter
Omid
Well-known member
A simpler version of your futuristic idea would be binoculars whose IPD could be locked once adjusted for a particular user. Why don't we have this feature?
John A Roberts
Well-known member
Hi Omid,
As I indicated in a recent post, a lockable IPD was a standard feature on Zeiss binoculars from their introduction in 1894!
(it seems to have lasted until the end of WWI but not much after)
From https://www.birdforum.net/showthread.php?t=381125:
‘ . . . The Zeiss design used a notch and an adjustable pin to record the IPD:
- the binocular could than be folded and put in it’s case, and
- when taken out and opened, the pin would fit into the notch at the set IPD
see the image from Anna & Terry Vacani’s website: http://www.binoculars-cinecollectors.com/html/body_educational_t_p2.html [it's again included in this post below]
While long out of fashion, it’s not an idea without merit, particularly as roof prism binoculars typically don’t include an IPD scale to enable checking the setting
And as an aside:
- on dual bridge designs like the Swarovski EL, it would be simple to place an IPD scale on the rear face of the front bridge for easy verification of the setting, and
- on other designs a scale could be placed on the front face of the bridge (a less convenient location than one visible from the rear while holding the binoculars, but nonetheless useful) . . . '
- - - -
The 4x11 unit used to illustrate the explanation above was #3,356. However, there are also images of much earlier units which also show the IPD lock:
- A 4x11 unit #7 dating from 1894 (the first year of production) at Historica Collectables:
http://www.historicacollectibles.co...pes/feldstecher-4x-c-zeiss-jena-drp-nr-7-1894
I’ve attached 3 images, but there are more - including 4 from an 1894 Zeiss pamphlet *
- A rare 4x14 Theatre Glass #26 also dating from 1894, at Johann Leichtfried’s site fernglasmuseum:
http://www.fernglasmuseum.at/museum..._2/zeiss_feldstecher-4fach_theaterglas_2.html
An attached image shows how it could be optionally folded to a more compact shape for theatre use
- so seemingly the earliest example of the vertically aligned ocular/ objective Porro configuration
e.g. compare it to the images that I previously posted at: https://www.birdforum.net/showpost.php?p=3878055&postcount=10
* a set of Zeiss pamphlets in either English or German dating from 1894 to 1905 - along with many issues of the Zeiss Historica Journal - can be found at:
https://issuu.com/zeisshistoricasociety/docs
All this material was originally on the now defunct Zeiss Historica site
While the journal articles are mainly about Zeiss cameras there are also articles about binoculars, telescopes and microscopes
John
p.s. the original offerings in the 1894 pamphlet were 4x11, 6x15 and 8x20, hence the evident size in the 4th image
As I indicated in a recent post, a lockable IPD was a standard feature on Zeiss binoculars from their introduction in 1894!
(it seems to have lasted until the end of WWI but not much after)
From https://www.birdforum.net/showthread.php?t=381125:
‘ . . . The Zeiss design used a notch and an adjustable pin to record the IPD:
- the binocular could than be folded and put in it’s case, and
- when taken out and opened, the pin would fit into the notch at the set IPD
see the image from Anna & Terry Vacani’s website: http://www.binoculars-cinecollectors.com/html/body_educational_t_p2.html [it's again included in this post below]
While long out of fashion, it’s not an idea without merit, particularly as roof prism binoculars typically don’t include an IPD scale to enable checking the setting
And as an aside:
- on dual bridge designs like the Swarovski EL, it would be simple to place an IPD scale on the rear face of the front bridge for easy verification of the setting, and
- on other designs a scale could be placed on the front face of the bridge (a less convenient location than one visible from the rear while holding the binoculars, but nonetheless useful) . . . '
- - - -
The 4x11 unit used to illustrate the explanation above was #3,356. However, there are also images of much earlier units which also show the IPD lock:
- A 4x11 unit #7 dating from 1894 (the first year of production) at Historica Collectables:
http://www.historicacollectibles.co...pes/feldstecher-4x-c-zeiss-jena-drp-nr-7-1894
I’ve attached 3 images, but there are more - including 4 from an 1894 Zeiss pamphlet *
- A rare 4x14 Theatre Glass #26 also dating from 1894, at Johann Leichtfried’s site fernglasmuseum:
http://www.fernglasmuseum.at/museum..._2/zeiss_feldstecher-4fach_theaterglas_2.html
An attached image shows how it could be optionally folded to a more compact shape for theatre use
- so seemingly the earliest example of the vertically aligned ocular/ objective Porro configuration
e.g. compare it to the images that I previously posted at: https://www.birdforum.net/showpost.php?p=3878055&postcount=10
* a set of Zeiss pamphlets in either English or German dating from 1894 to 1905 - along with many issues of the Zeiss Historica Journal - can be found at:
https://issuu.com/zeisshistoricasociety/docs
All this material was originally on the now defunct Zeiss Historica site
While the journal articles are mainly about Zeiss cameras there are also articles about binoculars, telescopes and microscopes
John
p.s. the original offerings in the 1894 pamphlet were 4x11, 6x15 and 8x20, hence the evident size in the 4th image
Attachments
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Omid
Well-known member
Thanks for your post John! Fascinating and informative as usual. So, it seems that binoculars with locking IPD existed already but somehow fell out of fashion or were simply neglected by manufacturers.
Looking at historical models and observing trends is always fascinating. Change is often introduced merely for the sake of change. This is the foundation of fashion industry and many other industries as well. A very interesting change was the switch to roof prism design. It is an inherently inferior design from all visual and optical aspects but gained popularity thanks to its more streamlined shape and fashion/marketing trends.
Looking at historical models and observing trends is always fascinating. Change is often introduced merely for the sake of change. This is the foundation of fashion industry and many other industries as well. A very interesting change was the switch to roof prism design. It is an inherently inferior design from all visual and optical aspects but gained popularity thanks to its more streamlined shape and fashion/marketing trends.
John A Roberts
Well-known member
Hello again Omid,
Most roof prisms are more compact then the Porro Type I and Type II designs, and compactness certainly explains a great deal of the current popularity of roof prism binoculars
However, it's interesting that compactness was not the initial stimulus for the design of roof prisms for use in binoculars
All of the significant roof prism designs date back to around the start of the 20th century, and were in response to Zeiss’ introduction of prismatic binoculars in 1894
The Zeiss binoculars were protected by Ernst Abbe’s patent, which included both the Porro designs
Other manufacturers had to come up with designs for prismatic binoculars that avoided obvious patent infringement
- and had to live with the unavoidable optical performance deficits compared to the Porro designs
I’ve recently started looking at the history, types and use of prisms in binoculars in some detail. So some context before I address the above
(and as it’s a work in progress, there may well need to be some corrections or additions)
Porro Prisms
Ignazio Porro experimented with the use of triangular prisms to erect an image in optical systems as early as 1850
In 1854 he patented this application for prisms in both Britain and France - see the attached information about the British patent
it’s from the compilation by Terence Wayland of ‘British Patents Relating To Small Telescopes And Binoculars’ at: http://home.europa.com/~telscope/Ross/British.patents.telescopes.&.binoculars.pdf
As can be seen, Porro described the use of what we know consider as both Porro Type I and Type II prisms:
- Type I, where 2 triangular prisms are facing each other while offset at 90 degrees, and
- Type II, where in effect 1 of the prisms is cut in half, and then attached to the other prism with the 2 halves facing in opposite directions
n.b. Porro Type II prisms are also referred to Abbe-Porro prisms (following on from Ernst Abbe’s 1893 patent)
Early Porro Prism Viewers & Glass Problem
Porro had the firms of J.G. Hofmann and Emil Busch, make small numbers of monocular telescopes using both prism types
see an image of one of Hofmann’s, from Larrry Gubas’ article in the Spring 1990 edition of the Zeiss Historica Journal, at: https://issuu.com/zeisshistoricasociety/docs
Significantly there is no indication that Porro designed any binocular prismatic devices
e.g. see Peter Abrahams comprehensive history of Porro, including his inventions at: http://home.europa.com/~telscope/porro.txt
The first known commercially made prismatic binoculars are attributed to:
- A. A. Boulanger in 1859, and
- Camille Nachet in 1875
Both are rare, there is little by way of description, and there are only 3 images readily available - 2 for the former and 1 for the latter
2 of the images are from: http://home.europa.com/~telscope/temp/ (go to ‘Porrokijker’)
and the 2nd Boulanger image is from: https://en.wikisource.org/wiki/1911_Encyclopædia_Britannica/Binocular_Instrument
As can be seen, the Boulanger design was closely based on that of the field glasses of the era, with the prisms rigidly attached to the eyepiece section
It had:
- central focusing by objective movement in front of the prism/ eyepiece assembly
- an additional wheel to adjust the IPD, and
- eyepieces located above the objectives (so with no significant horizontal offset of the objective axes compared to the eyepieces)
While the Nachet design was essentially the same:
- it dispensed with the IPD adjustment wheel, but
- seemingly had more offset of the objective axes (though still small at around 13 mm/ 0.5” on each side, according to the indicated dimensions, and varied depending on the IPD)
A common problem for all of the above was the quality of the available optical glass
While the imperfections were tolerable in lens only systems, the added volume of glass that the light had to travel through in prismatic systems,
meant that the images were notably inferior to those of existing non-prism alternatives
Most roof prisms are more compact then the Porro Type I and Type II designs, and compactness certainly explains a great deal of the current popularity of roof prism binoculars
However, it's interesting that compactness was not the initial stimulus for the design of roof prisms for use in binoculars
All of the significant roof prism designs date back to around the start of the 20th century, and were in response to Zeiss’ introduction of prismatic binoculars in 1894
The Zeiss binoculars were protected by Ernst Abbe’s patent, which included both the Porro designs
Other manufacturers had to come up with designs for prismatic binoculars that avoided obvious patent infringement
- and had to live with the unavoidable optical performance deficits compared to the Porro designs
I’ve recently started looking at the history, types and use of prisms in binoculars in some detail. So some context before I address the above
(and as it’s a work in progress, there may well need to be some corrections or additions)
Porro Prisms
Ignazio Porro experimented with the use of triangular prisms to erect an image in optical systems as early as 1850
In 1854 he patented this application for prisms in both Britain and France - see the attached information about the British patent
it’s from the compilation by Terence Wayland of ‘British Patents Relating To Small Telescopes And Binoculars’ at: http://home.europa.com/~telscope/Ross/British.patents.telescopes.&.binoculars.pdf
As can be seen, Porro described the use of what we know consider as both Porro Type I and Type II prisms:
- Type I, where 2 triangular prisms are facing each other while offset at 90 degrees, and
- Type II, where in effect 1 of the prisms is cut in half, and then attached to the other prism with the 2 halves facing in opposite directions
n.b. Porro Type II prisms are also referred to Abbe-Porro prisms (following on from Ernst Abbe’s 1893 patent)
Early Porro Prism Viewers & Glass Problem
Porro had the firms of J.G. Hofmann and Emil Busch, make small numbers of monocular telescopes using both prism types
see an image of one of Hofmann’s, from Larrry Gubas’ article in the Spring 1990 edition of the Zeiss Historica Journal, at: https://issuu.com/zeisshistoricasociety/docs
Significantly there is no indication that Porro designed any binocular prismatic devices
e.g. see Peter Abrahams comprehensive history of Porro, including his inventions at: http://home.europa.com/~telscope/porro.txt
The first known commercially made prismatic binoculars are attributed to:
- A. A. Boulanger in 1859, and
- Camille Nachet in 1875
Both are rare, there is little by way of description, and there are only 3 images readily available - 2 for the former and 1 for the latter
2 of the images are from: http://home.europa.com/~telscope/temp/ (go to ‘Porrokijker’)
and the 2nd Boulanger image is from: https://en.wikisource.org/wiki/1911_Encyclopædia_Britannica/Binocular_Instrument
As can be seen, the Boulanger design was closely based on that of the field glasses of the era, with the prisms rigidly attached to the eyepiece section
It had:
- central focusing by objective movement in front of the prism/ eyepiece assembly
- an additional wheel to adjust the IPD, and
- eyepieces located above the objectives (so with no significant horizontal offset of the objective axes compared to the eyepieces)
While the Nachet design was essentially the same:
- it dispensed with the IPD adjustment wheel, but
- seemingly had more offset of the objective axes (though still small at around 13 mm/ 0.5” on each side, according to the indicated dimensions, and varied depending on the IPD)
A common problem for all of the above was the quality of the available optical glass
While the imperfections were tolerable in lens only systems, the added volume of glass that the light had to travel through in prismatic systems,
meant that the images were notably inferior to those of existing non-prism alternatives
Attachments
Last edited:
John A Roberts
Well-known member
John A Roberts
Well-known member
Ernst Abbe
Ernst Abbe was a remarkable figure who had a profound effect both on optical development in general, and the company of Carl Zeiss in particular
- see the attached history from Zeiss
Abbe took a systematic approach to optical problems, which included encouraging Otto Schott to establish a glass works in 1882
Schott’s progress in improving glass quality, eventually solved the problem of using prisms in optical devices
In terms of his own experimentation, as early as 1873 Abbe had exhibited a prototype telescope using what we would describe as Porro Type I prisms
see the image which is also from Larry Gubas’ article in the Spring 1990 edition of the Zeiss Historica Journal
However as it turned out, Abbe was unaware of Porro’s earlier patent for the use of prisms to erect an image in an optical device
When he went to register his patent for binocular viewing devices, the initial application was refused when a search found the earlier Porro patent
i.e. Abbe could not claim the use of Porro type prisms to erect an image as an original feature
(this seems to also indicate that Abbe was unaware of any of the earlier monocular or binocular devices that used prisms - so some indication of the extreme rarity of all of them)
Abbe's Patent - Zeiss Prism Binoculars
Abbe’s revised patent was filed in Germany in 1893 (and also in many other European countries and the USA in either 1893 or 1894)
It’s primary claim was the use of prisms to give enhanced stereoscopic viewing in binocular devices (compared to current non-prismatic in-line field glasses)
The patent included images of:
- both a binocular and a ‘stereo-telescope’ (a hand held instrument with laterally adjustable barrels) showing their construction, and
- what we know as both Porro Type I and Porro Type II prisms, along with various constructions for each
See the attached copy of the US application, along with 2 images from the patent, and also an image showing the Stereo-Telescope (aka as a Relief Fernrohr in German)
the last image is from the an article by Jack Kelly in the Spring 2000 edition of Zeiss Historica Journal at: https://issuu.com/zeisshistoricasociety/docs
Zeiss commenced production of Abbe's prism binoculars in 1894
Effect of Patent
While the patent primarily covered enhanced binocular viewing, it also included the designs for both types of Porro prisms
And at the time Zeiss was particularly zealous in taking action against those who it believed were infringing it’s patent protections
In this context, the chronology below makes clear that initial roof prism developments were in response to the limitations imposed by the Abbe patent
Ernst Abbe was a remarkable figure who had a profound effect both on optical development in general, and the company of Carl Zeiss in particular
- see the attached history from Zeiss
Abbe took a systematic approach to optical problems, which included encouraging Otto Schott to establish a glass works in 1882
Schott’s progress in improving glass quality, eventually solved the problem of using prisms in optical devices
In terms of his own experimentation, as early as 1873 Abbe had exhibited a prototype telescope using what we would describe as Porro Type I prisms
see the image which is also from Larry Gubas’ article in the Spring 1990 edition of the Zeiss Historica Journal
However as it turned out, Abbe was unaware of Porro’s earlier patent for the use of prisms to erect an image in an optical device
When he went to register his patent for binocular viewing devices, the initial application was refused when a search found the earlier Porro patent
i.e. Abbe could not claim the use of Porro type prisms to erect an image as an original feature
(this seems to also indicate that Abbe was unaware of any of the earlier monocular or binocular devices that used prisms - so some indication of the extreme rarity of all of them)
Abbe's Patent - Zeiss Prism Binoculars
Abbe’s revised patent was filed in Germany in 1893 (and also in many other European countries and the USA in either 1893 or 1894)
It’s primary claim was the use of prisms to give enhanced stereoscopic viewing in binocular devices (compared to current non-prismatic in-line field glasses)
The patent included images of:
- both a binocular and a ‘stereo-telescope’ (a hand held instrument with laterally adjustable barrels) showing their construction, and
- what we know as both Porro Type I and Porro Type II prisms, along with various constructions for each
See the attached copy of the US application, along with 2 images from the patent, and also an image showing the Stereo-Telescope (aka as a Relief Fernrohr in German)
the last image is from the an article by Jack Kelly in the Spring 2000 edition of Zeiss Historica Journal at: https://issuu.com/zeisshistoricasociety/docs
Zeiss commenced production of Abbe's prism binoculars in 1894
Effect of Patent
While the patent primarily covered enhanced binocular viewing, it also included the designs for both types of Porro prisms
And at the time Zeiss was particularly zealous in taking action against those who it believed were infringing it’s patent protections
In this context, the chronology below makes clear that initial roof prism developments were in response to the limitations imposed by the Abbe patent
Attachments
Last edited:
John A Roberts
Well-known member
John A Roberts
Well-known member
Roof Prisms
Introduction
A ‘roof’ in a reflective optical prism, describes the presence of 2 intersecting reflective surfaces in the path of the light beam as it travels through the prism (vs a single reflective surface)
The consequence of the intersecting roof is that the light beam is split in half, with each half first striking one of the two surfaces and then the other
The word ‘roof’ comes from the original German description of it as a Dach or Dachstein prism, where Dachkante means a roof edge
For more detail see the Wikipedia entry at: https://en.wikipedia.org/wiki/Roof_prism
n.b. To accomplish the erecting function, there must be an even number of reflections in a prism system (typically either 4 or 6)
However, a contrary impression is given in many roof prism diagrams, as they fail to make clear the 2 converging roof surfaces - and the 2 reflections
e.g. see the attached Amici and Schmidt-Pechan prism images
- Amici Roof Prism
The first patent for a roof prism was that of Giovanni Amici in 1823. The Amici prism is a roofed right angle prism
It’s uniqueness - compared to a regular right angle prism - is that it both deviates a light beam by 90 degrees and also inverts it (compare the two images)
(the regular right angle prism is from Optica at: http://www.opticsindia.com/product/right-angle-prism/ )
- Roof Pentaprism
The roof pentaprism was invented by Charles Goulier around 1850. It provided the basis for Hensoldt’s Penta roof prism of 1897
i.e. where a roof pentaprism is combined with a triangular prism to turn the light path an additional 90 degrees
Introduction
A ‘roof’ in a reflective optical prism, describes the presence of 2 intersecting reflective surfaces in the path of the light beam as it travels through the prism (vs a single reflective surface)
The consequence of the intersecting roof is that the light beam is split in half, with each half first striking one of the two surfaces and then the other
The word ‘roof’ comes from the original German description of it as a Dach or Dachstein prism, where Dachkante means a roof edge
For more detail see the Wikipedia entry at: https://en.wikipedia.org/wiki/Roof_prism
n.b. To accomplish the erecting function, there must be an even number of reflections in a prism system (typically either 4 or 6)
However, a contrary impression is given in many roof prism diagrams, as they fail to make clear the 2 converging roof surfaces - and the 2 reflections
e.g. see the attached Amici and Schmidt-Pechan prism images
- Amici Roof Prism
The first patent for a roof prism was that of Giovanni Amici in 1823. The Amici prism is a roofed right angle prism
It’s uniqueness - compared to a regular right angle prism - is that it both deviates a light beam by 90 degrees and also inverts it (compare the two images)
(the regular right angle prism is from Optica at: http://www.opticsindia.com/product/right-angle-prism/ )
- Roof Pentaprism
The roof pentaprism was invented by Charles Goulier around 1850. It provided the basis for Hensoldt’s Penta roof prism of 1897
i.e. where a roof pentaprism is combined with a triangular prism to turn the light path an additional 90 degrees
Attachments
Last edited:
John A Roberts
Well-known member
Binocular Roof Prism Chronology
The development of the main roof prisms types used in hand held binoculars, in terms of patent application dates, seems to be:
1895 - Sprenger-Leman (has a large offset of the eyepiece and objective axes; used in 1907 Zeiss Teleplast, and with different roof surfaces in 1920 Moller Theatis)
1897 - Hensoldt Penta (also has offset of eyepiece and objective axes; used in 1897 Hensoldt Pentaprism Binocle)
1899 - Schmidt-Pechan (dominant modern RP choice; first use in 1964 Zeiss 8x30 B Dialyt?)
1905 - Abbe-Koenig (other common modern RP choice; used in 1905 Hensoldt Dialyt - the first in-line eyepiece/ objective prismatic binocular)
1907 - Uppendahl (first use in 1963 Leitz v2 Trinovid?, also current 2nd generation Leica Geovid rangefinder binoculars)
- - - -
Then in the 1920’s:
1920 - Moller (in effect a less efficient Hensoldt Penta, seemingly to enable the claim of a new design; used in 1923 Moller Tourix and Tourox)
[1923 - Zeiss Telita I binocular (a variant of the Moller, includes different roof location and reflection pattern; seemingly as part of a dispute with Moller)]
[1927 - Zeiss Telita II binocular (another variant, again includes a different roof location and reflection pattern; and again seemingly as part of the dispute with Moller)]
- - - -
1949 - Ludewig (a combined mirror/ prism design; used in 1956 Leitz Amplivid, and 1958 Leitz v1 Trinovid)
And for completeness
2010 - Perger Porro (sic) (a non-roofed design combined with small optical axes offset; three versions included in patent; one is used in current 3rd generation Leica Geovid rangefinder binoculars)
Interestingly, while the Schmidt-Pechan was developed by 1899, it did not achieve it’s current market dominance until well after the widespread adoption of single layer anti-reflective coatings following WWII
(and the Schmidt-Pechan has the unique requirement that the 2 prisms in the pair must be physically separated, as the the facing surfaces perform both transmission and reflection functions)
John
Image Sources:
1 and 6 are from Walter Besenmatter’s presentation ‘Die Moller-Zeiss-Story’ at: http://home.europa.com/~telscope/temp/Besenmatter.2006.M%F6ller-Zeiss.do.not.duplicate.pdf
5 and 9 are from Holger Merlitz:
- see the download here: https://www.juelich-bonn.com/jForum/read.php?9,419177,419553
- and another here: https://www.juelich-bonn.com/jForum/read.php?9,435679,435679
7 is from Jack Kelly’s article ‘Moller and Zeiss Compact Binoculars’ in the Spring 1999 edition of the Zeiss Historica Journal, at: https://issuu.com/zeisshistoricasociety/docs
The development of the main roof prisms types used in hand held binoculars, in terms of patent application dates, seems to be:
1895 - Sprenger-Leman (has a large offset of the eyepiece and objective axes; used in 1907 Zeiss Teleplast, and with different roof surfaces in 1920 Moller Theatis)
1897 - Hensoldt Penta (also has offset of eyepiece and objective axes; used in 1897 Hensoldt Pentaprism Binocle)
1899 - Schmidt-Pechan (dominant modern RP choice; first use in 1964 Zeiss 8x30 B Dialyt?)
1905 - Abbe-Koenig (other common modern RP choice; used in 1905 Hensoldt Dialyt - the first in-line eyepiece/ objective prismatic binocular)
1907 - Uppendahl (first use in 1963 Leitz v2 Trinovid?, also current 2nd generation Leica Geovid rangefinder binoculars)
- - - -
Then in the 1920’s:
1920 - Moller (in effect a less efficient Hensoldt Penta, seemingly to enable the claim of a new design; used in 1923 Moller Tourix and Tourox)
[1923 - Zeiss Telita I binocular (a variant of the Moller, includes different roof location and reflection pattern; seemingly as part of a dispute with Moller)]
[1927 - Zeiss Telita II binocular (another variant, again includes a different roof location and reflection pattern; and again seemingly as part of the dispute with Moller)]
- - - -
1949 - Ludewig (a combined mirror/ prism design; used in 1956 Leitz Amplivid, and 1958 Leitz v1 Trinovid)
And for completeness
2010 - Perger Porro (sic) (a non-roofed design combined with small optical axes offset; three versions included in patent; one is used in current 3rd generation Leica Geovid rangefinder binoculars)
Interestingly, while the Schmidt-Pechan was developed by 1899, it did not achieve it’s current market dominance until well after the widespread adoption of single layer anti-reflective coatings following WWII
(and the Schmidt-Pechan has the unique requirement that the 2 prisms in the pair must be physically separated, as the the facing surfaces perform both transmission and reflection functions)
John
Image Sources:
1 and 6 are from Walter Besenmatter’s presentation ‘Die Moller-Zeiss-Story’ at: http://home.europa.com/~telscope/temp/Besenmatter.2006.M%F6ller-Zeiss.do.not.duplicate.pdf
5 and 9 are from Holger Merlitz:
- see the download here: https://www.juelich-bonn.com/jForum/read.php?9,419177,419553
- and another here: https://www.juelich-bonn.com/jForum/read.php?9,435679,435679
7 is from Jack Kelly’s article ‘Moller and Zeiss Compact Binoculars’ in the Spring 1999 edition of the Zeiss Historica Journal, at: https://issuu.com/zeisshistoricasociety/docs
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John A Roberts
Well-known member
Omid
Well-known member
Wow!! What fascinating series of posts!! Thank you very much John! I have only read the first post on the genesis of the prismatic binoculars so far but I wanted to write and thank you before I read the rest of your material. I am heading out for lunch now, will read the rest of your posts in the afternoon.
Thank you very much again for contributing to this topic. Feel free to take over this thread and post here as much as you like. I will interject only occasionally if I have anything novel to say..
-Omid
Thank you very much again for contributing to this topic. Feel free to take over this thread and post here as much as you like. I will interject only occasionally if I have anything novel to say..
-Omid
John A Roberts
Well-known member
Hi Omid,
Thanks for your kind words
I was initially inclined to put all of the above in a new thread, and then link to it on this thread
However, as a new thread I would have wanted to precede it with much more introductory information about optics and especially the function of prisms in them
(which would have then simplified the path for future detailed comments about the individual prism types and comparisons between them)
In one sense I’m surprised that I needed to post the above, since it’s fundamental to so much discussion on the forum
- as many of the individual points are raised time and time again, one would think that the information would already be available as a whole
And certainly when I first had a renewed interest in binoculars, it was one of several basic things I looked for without success
i.e. a coherent and reasonably detailed history of the various types of prisms
(which is the same for a number of other topics that I've posted about in detail - I was surprised that the information was not already available in an organised form)
While I’m happy to contribute to this thread where I can add something of interest, I certainly don’t want to take over what is essentially your thread
While it’s ‘free ranging’, the starting topic is clearly about your perspectives based on your particular knowledge and experience
John
Thanks for your kind words
I was initially inclined to put all of the above in a new thread, and then link to it on this thread
However, as a new thread I would have wanted to precede it with much more introductory information about optics and especially the function of prisms in them
(which would have then simplified the path for future detailed comments about the individual prism types and comparisons between them)
In one sense I’m surprised that I needed to post the above, since it’s fundamental to so much discussion on the forum
- as many of the individual points are raised time and time again, one would think that the information would already be available as a whole
And certainly when I first had a renewed interest in binoculars, it was one of several basic things I looked for without success
i.e. a coherent and reasonably detailed history of the various types of prisms
(which is the same for a number of other topics that I've posted about in detail - I was surprised that the information was not already available in an organised form)
While I’m happy to contribute to this thread where I can add something of interest, I certainly don’t want to take over what is essentially your thread
While it’s ‘free ranging’, the starting topic is clearly about your perspectives based on your particular knowledge and experience
John
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Omid
Well-known member
Hi John,
I read the rest of your posts yesterday and learned a lot! Thank you very much again for posting your informative reviews of historical models and their evolution. I did not know that the roof models were developed in reaction to Abbe patents.
I look forward to reading more of your posts. Feel free to post them here and I'll post here if I have something to contribute too. As you noted, it is very important that the information is "in organized form". That's not really the goal of a forum like this but having one dedicated topic could be a close approximation
I read the rest of your posts yesterday and learned a lot! Thank you very much again for posting your informative reviews of historical models and their evolution. I did not know that the roof models were developed in reaction to Abbe patents.
I look forward to reading more of your posts. Feel free to post them here and I'll post here if I have something to contribute too. As you noted, it is very important that the information is "in organized form". That's not really the goal of a forum like this but having one dedicated topic could be a close approximation
Omid
Well-known member
The method of erecting images using one or more prisms is fascinating. I would like to know how critical the alignment of the erector prims is. Specifically, what will happen to the real image formed at the objective focal plane if
a) the optical axis of the erector unit is tilted by an angle Alpha with respect to the optical axis of the objective
b) the optical axis of the erector unit is shifted by an amount Delta with respect to the objective optical axis.
In the above question I assumed that the erector unit has an optical center or axis. I asked these questions in another topic but did not get a clear answer.
Another aspect that I would like to know is what happens if the focused beam produced by the objective is converged inside the erector prism. Is possible for the prisms to work as erectors in this case?
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a) the optical axis of the erector unit is tilted by an angle Alpha with respect to the optical axis of the objective
b) the optical axis of the erector unit is shifted by an amount Delta with respect to the objective optical axis.
In the above question I assumed that the erector unit has an optical center or axis. I asked these questions in another topic but did not get a clear answer.
Another aspect that I would like to know is what happens if the focused beam produced by the objective is converged inside the erector prism. Is possible for the prisms to work as erectors in this case?
|>|
Omid
Well-known member
I keep learning new facts about the human visual system: The most recent thing I have learned is that the eye lens is not perfctly symmetric. According to experts, this is due to the irrigularities of human growth. Unlike a binocular lens, the eye lens is not symmetrical around its "optical axis". Even more interesting is that the eye's imaging senor (effectively the fovea part of the retina) is not centered on the optical axis of the lens. These two features have very interesting ramifications:
The eye's perception of color can change depending on what part of your eye pupil is being illuminated by your binoculars. This can explain varying color perceptions that binocular users attribute to a specific binoculars model. A slight change in the IPD can effect the color balance of a scene being viewed.
A few months ago when I was trying to aim a rifle with iron sights I noticed that if I cover my eye by a patch that has a small hole in it, my eyesight improves and I see the target with better contrast. I also noticed, looking through the hole, that shifting the position of the hole over my eye by a slight amount could cause a perceived shift in the position of the image I am seeing! At that time I attributed these effects to my age (I am not too old, in late 40's now) but now I realise that these are natural and has to do with natural imperfections of the eye's lens.
The eye's perception of color can change depending on what part of your eye pupil is being illuminated by your binoculars. This can explain varying color perceptions that binocular users attribute to a specific binoculars model. A slight change in the IPD can effect the color balance of a scene being viewed.
A few months ago when I was trying to aim a rifle with iron sights I noticed that if I cover my eye by a patch that has a small hole in it, my eyesight improves and I see the target with better contrast. I also noticed, looking through the hole, that shifting the position of the hole over my eye by a slight amount could cause a perceived shift in the position of the image I am seeing! At that time I attributed these effects to my age (I am not too old, in late 40's now) but now I realise that these are natural and has to do with natural imperfections of the eye's lens.
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You won't have collimation in both cases. With further degradations in the angular case (a) with respect to the passing band within the prismatic system, relative to the angle of incidence.
If the inclination is symmetrical and opposite, it is possible to create what Perger did in his prism, managing to restrict the typical separation of the optical axes in input and output and using less glass for the same work.
The out of collimation in case (B) is related to the displacement of the output image, but with various degradations also here, due to the usual optical reasons of non-concentricity of the system.
Obviously, if the image of the lens has not passed the optical path of the prism, it will not be erected. But hypothetically it is also possible to make the prism work as you ask, having the image positioned in the middle of its path (say the Porro-prism case) and using eyepieces with draft much longer than normal. Usually the image of the lens gets to be almost inside the body of the eyepieces.
Disassemble a broken pair of binoculars and do two tests. Direct experience explains better than a thousand words.
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