For pragmatic reasons optics manufacturers like to share components within product lines. As I previously indicated:
. . .
As in many other industries, inventory management is a huge concern for optics manufacturers
In Swarovski Optik’s 70th Anniversary video it’s stated that they manufacture around 9,500 different parts for their product range,
see here:
https://www.birdforum.net/showthread.php?t=375640
And presumedly they also order in a huge range of additional parts:
- both standard pattern items like screws and washers
- along with specialised items such as rubber armour mouldings
So even with computerised inventory management and Just In Time supply practices, their on-hand inventory at any time must be enormous
Consequently, when a company designs something like a series of binoculars . . . it tries to use as many common parts as possible
And that's the approach taken by Meopta with the B1 line, especially with the x42 and larger models
Looking at both the images in post #43, along with the specifications (see a copy from the 2019 US catalogue that also handily includes transmission data),
it’s clear that:
a) the x32 models use a smaller body and focuser, along with smaller eyepiece and objective assemblies, while
b) the x42, x50 and x56 models all share a common body, and vary the eyepiece and objective assemblies
(the attached cutaways show how the seperate objective and eyepiece units are attached to the main body)
In terms of specific details of the internal construction, there are only two images that I’m aware of:
• an unspecified x42 model (most probably the 8x42?; the image dates back to 2005, when the B1 line was introduced), and
• the 10x42 HD model (in 2013 the 10x42 was upgraded by the use of HD glass for one of the lenses in the objective group; the image is from the 2019 US catalogue)
A) Objectives
Both cutaway x42 images show an uncommon objective arrangement. It consists of a conventional achromatic doublet along with a single lens focuser *
However, a 4th lens is fixed immediately in front of the first prism. Presumedly this contributes to the short length of the x42 series
i.e. it allows a shorter then usual physical length for a given focal length
However, it does not seem that this arrangement is necessarily used on all of the larger models (or perhaps even on the x32 ones)
Roger Vine noted when using a laser pointer to illuminate the inside of the objective housings of the 7x50 and 12x50 HD,
that both appear to have ‘ . . . cemented doublets with doublet focusing lenses behind.’ See his review of each at:
http://www.scopeviews.co.uk/BinoReviews.htm
So while these x50 models also use four lenses, it's not in the same configuration as the x42’s
* in addition, while the earlier image shows the achromat as a cemented pair, the achromat of the 10x42 HD seems to have an air gap between the lenses
B) Prisms
Notwithstanding comments to the contrary, all models including the x56 ones use Schmidt-Pechan prisms, see:
https://www.birdforum.net/showpost.php?p=3960026&postcount=43
The x32 models necessarily use smaller prisms than the larger models. However, as all the larger models have a common body, it’s highly likely that they use the same prisms
That, along with the use of aluminium alloy for the housings (rather than magnesium), could explain why the x42 models are heavier than most of those from other manufacturers
C) Eyepieces
Looking at the information in the table, and using the expedient of multiplying magnification by Field Of View in degrees,
it can be seen that most models have a nominal AFOV of around 63 degrees
The obvious exceptions are the 7x50 at 55 degrees and the 8x56 at 51 degrees
The Eye Relief figures reinforce that various eyepiece configurations are used to alter the magnifications
And as can be seen:
- the earlier x42 image (the 8x42?) shows 4 lenses in 3 groups, in a 1/ 2/ 1 configuration, while
- the 10x42 HD has 5 lenses in 3 groups, in a 2/ 2/ 1 configuration
And finally, as noted by Roger Vine the two x50 models that he tested had different diameter eye lenses
John
