Collimating Bear 15 x 70 Binoculars
(From Pete Rasmussen on s.a.a via Bob Midiri)
See also Lisa Compton's experiences
The typical collimation procedure with the 15x70 BEAR binoculars is
often as a simple operation. An exception to this is when the binoculars are
in gross misalignment. Gross misalignment is easily determined when the
light seen coming in from the eyepiece end, as viewed directly from and
through the objective end, looks skewed significantly off center of the
internal binocular. In other words, this large disc of light, which is the
aperture opening of the eyepiece itself, will not be seen as concentric
(circularly centered) with the circles that make up the prism hole and the
objective lens circumference as viewed together in series from the front
(objective) end of the binoculars.
If the binoculars had become just minor misaligned, or are not exactly
aligned to start with, most often a slight tweaking of one or both of the
tiny set screws that tilt the rear prisms (nearest the eyepieces) is all that
is required. This should be all it takes to true up the parallel nature of
the two tube assemblies that make up the binocular vision.
To do this, one should set the binos on a solid surface pointing
horizontally, while centering a focused image of a prominent distant (about
1/2 mile or more) fixed object. Tripod mounting is also optionally good for
stabilizing the binos and may be preferred to the solid surface approach.
Take a very small (about 1 mm) jeweler's flat bladed screwdriver and stick
it into the gap at the edge of the rubber covering next to the prism covers.
These prism covers are the ones with the name and specifications on them and
are located under the eyepieces. The location to do this "prying" is right
above the word "Bear" on the left tube assembly, and also above the numbering
"15x70" on the right tube assembly.
Work the screwdriver tip back and forth as to pry and loosen the attachment
of the rubber from the body. When you get it separated far enough so you are
able to grasp the edge of the rubber covering with thumb and forefinger, and
allow the set screw hole to be easily accessed, place the screwdriver tip
into the set screw slot in the set screw hole. Next, place the eyes about 6"
away from the eyepieces while looking at the distant fixed object through
both bino tubes.
Turn this tiny set screw back and forth slowly less than 1/4 turn each way
while watching the images change. You will see the images more or less to
split or join together. Find and stop on the spot that seems to be best for
a well joined image as viewed through both bino tubes. Note: Instead of
being 6" away, you may have better results trying this procedure with the
eyes right up to the binoculars as they would be normally used.
If the image still seems to remain a bit out of alignment, the set screw on
the other tube can be turned in the same manner to walk the images together
at a 90 degree angle to that of the first one. That should be all it takes
to get good alignment for both tubes. The rubber covering will normally
spring right back into place.