25/40×100 Basic Operation

Oberwerk 25/40×100 Long-Range Observation Binocular

Setting up the Tripod

  • Unbuckle the strap that holds the legs together for transport.tripodhand
  • Spread the legs to their maximum angle and place on the floor.
  • Set the leg length for your height, a good starting point is to lower each leg by 8″ to 10″ from the fully collapsed position.  Loosen the leg clamp thumbscrew and lower each leg evenly, all legs need to be the same length for the tripod to be level.  Tighten the leg clamps firmly so the leg does not slip and collapse under the weight of the binocular.
  • Push down on the top of the tripod to be certain none of the legs will slip.

WARNING- Occasionally check the tightness of the leg clamps as wood can expand and contract with changes in humidity.

Using the Tripod

  • Carefully lift the binocular from the case and slip the tubular mount over the shaft on the top of the tripod.  Note that the mount post is folded to the back in order to fit in the case, which means the binocular’s initial position will be pointing almost straight up.
  • Once the binocular is seated on the tripod, tighten the lower thumbscrew on the mount shaft to lock the binocular onto the tripod.
  • Grab the binocular with a hand at each end and firmly pull it level so that it is pointing out to the horizon.
  • The upper knob on the mount shaft is used to tighten or lock the altitude bearing, this can be left fully loosened.
  • To steer the binocular, place both hands on the prism housings (the large black “cans” just forward of the eyepiece turrets), and apply firm pressure to move left/right or tilt up/down.
  • Once the binocular is mounted on the shaft, do not attempt to make large adjustments in tripod height. Small adjustments can be carefully made by using one hand to grip the upper part of the leg to act as a temporary “stop” when loosening the leg tensioner. Move each leg no more than two inches at a time to prevent the tripod from becoming unbalanced.
  • We recommend that you remove the binocular from the tripod when moving it to another viewing location.


Eyepieces and Focusers

  • The Oberwerk 25/40×100 comes with two eyepiece pairs, for low and2450eps high power, mounted on rotating turrets.  The smaller eyepieces are 40x magnification, the larger ones are 25x magnification. Rotate the turrets until they snap into position, as shown below.  It’s best to start with the 25x eyepieces.
  • Adjust the IPD (Inter-Pupillary Distance). This matches spacing of the eyepieces to spacing of your eyes.  While looking through the eyepieces, grab the big round prism housings (the black cans) and twist them to move them in or out. They are internally geared, and move together. Move them until both eyes are seeing whole and well-merged images.
  • Each of the eyepieces has a built-in helical focuser. To focus on an object, gently close one eye and adjust the opposite focuser (rotate the grip ring clockwise/counter-clockwise) until the image is in sharp focus. The eyepiece must move inward (clockwise) to focus on distant objects, and outward (counter-clockwise) to focus on closer objects.  Close the other eye and repeat for the other eyepiece.
  • The focus range using the 25x eyepieces is from about 50 feet to infinity (the night sky). On the other hand, the 40x eyepieces have a focus range of roughly a half-mile to infinity.  Only the 25x eyepieces can be used when viewing targets less than a half-mile away.

General Viewing Info

  • Viewing through a window?  Viewing through a window may degrade the quality of the image through the binocular.  For most windows, the effect on image quality is minimal, but certain windows, especially triple-glazed, or those with screens, can noticeably degrade the view, especially at 40x magnification.  If image quality is less than expected, set up the binocular outdoors to see if the problem is due to the window.
  • This binocular is not weatherproof.  While it can be used outdoors, do not leave it outside if there is a chance of rain- unless you are using our weatherproof cover.