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USING YOUR BT-ED70S-A BINOCULAR TELESCOPE

ALIGNMENT

1

T h e   B T - E D 7 0 S - A   h a s   t h r e a d e d   s o c k e t s   o f   1 / 4 ” - 2 0   a n d  

a   3 / 8 ”   o n   t h e   b o t t o m   o f   t h e   d o v e t a i l   b a r   t h a t   f i t   d i r e c t l y  
t o   a   c a m e r a   t r i p o d .

3

  While looking through the right side eyepiece, turn the focus 

ring on the right side prism housing until the image appears in 
sharp focus.  Next, look through the left side eyepiece and 
adjust the focus of the left side eyepiece in the same way by 
turning the left side focus ring.  

2

 Attach the eyepieces so that the chrome barrel of the eyepiece 

is push into the eyepiece holder and fixed by friction.  When 
you exchange the eyepieces, you should align the optical axis 
of left side and right side eyepieces in the procedure stated in 
ALIGNMEMT.

4

 Adjust the interpupillary width to your eyes.  Hold the left and 

right side prism housings with both hands and rotate them 
inward equally so that the both eyepieces come to a position 
that fits your eyes.  It is a point that circles of field of view in the 
left and right eyepieces become one completely.

How to Adjust a Double Vision

1

Look through the left side eyepiece and find an object 

further than 1,000m distant.  Put the object in the field of 
view so that it lies on the imaginary horizontal center line of 
the field of view, and shift it to the very right edge.  An 
electric pole is shown here as a sample.  

The object near the edge of the field of view makes your 
recognition of a position of the object against the field of 
view circle easier.

If the object is seen at the same level and position on the 
right side eyepiece as seen with the left side eyepiece, it 
shows that the eyepieces are aligned correctly.

If not, rotate the right side eyepiece slowly clockwise or 
counterclockwise until the object moves toward the same position.

2

If the above does not align the optics correctly, then rotate 

the  left side eyepiece slowly while keeping the right side 
eyepiece as it is.

TIPS ON GENRAL OBSERVATION WITH BT-ED70S-A

The object can be seen clearer and brighter at low 
magnification.  It is desirable to start with a pair of eyepieces with low magnification and exchange them for eyepieces with 
medium magnification. It will be hard to align the optical axis at high magnification due to the structure of binocular telescopes.
It is advisable to use with the Vixen NLV or LVW eyepieces with focal length longer than 10mm for high magnification. 

It may be possible that a double vision occurs from the character of binoculars when you attach the eyepieces without
a consideration for optical alignment.  In this case, make adjustments of the optical axis in the following procedure.

1

 

Left

Right

Right

Left

1

2

3

4

2

D o v e t a i l   b a r

1 / 4 ” - 2 0
3 / 8 ”

Right side 
prism housing

Left side 
prism housing

Eyepieces
(Optional)

Eyepiece holder

Chrome 

barrel

C a m e r a   t r i p o d

L e f t   s i d e   f o c u s   r i n g

D o v e t a i l   b a r

1 / 4 ” - 2 0
3 / 8 ”

Right side 
prism housing

Left side 
prism housing

Eyepieces
(Optional)

Eyepiece holder

Chrome 

barrel

C a m e r a   t r i p o d

L e f t   s i d e   f o c u s   r i n g

R i g h t   s i d e   f o c u s   r i n g

R i g h t   s i d e   f o c u s   r i n g

Imaginary horizontal center line

Shift the object to the very right edge

60キ-12-0.1S-50-

(PIXEL1160)

M

5-17-3 H i gash itokorozawa,Tokorozawa, Sa i tama 359-0021,  Japan
P h o n e   +81-4-2944-4141(International)
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