Binocular Testing

by: OZScopes - The Australian Telescope Experts

At OzScopes, we always try to offer the best quality scopes at good prices. However, some defaults may occasionally occur during the manufacturing process. So, when you make a purchase with us, it is important to check its quality once received. If unsatisfied, contact us and we will gladly assist you with a replacement or refund.

Things to look out for in binoculars:
1.Look carefully at the objective lenses. Reject the binocular if you see signs of scratches or dirt.

2.The hinge should work smoothly, with steady resistance. Pick the binoculars up and move the halves back and forth. Look for any play in the joints or anything that indicates damage.

3.Hold the binoculars at arms length away from you pointing them towards the sky or a window with bright light. Exit pupils should be truly circular and uniformly bright.

4.If after using the binoculars for several minutes your eyes feel uncomfortable, this might indicate that the binoculars might be out of collimation, and thus the two barrels don’t point in the same direction, resulting in image appearing misaligned.

5.Use your binoculars to find a high-contrast object such as a tree against the daytime sky, and place it in the center of the field. If you see strong green or violet fringes of light along the edges of the object, the binoculars may suffer from chromatic aberration. This problem is especially prevalent with high magnification lenses and can be a real problem for birders who may want accurate color rendition. See figure 1.

6.The ultimate test for your binoculars is to use it to observe a bright star at night. After having the star centered in the field of view and bringing a binoculars to good focus, the star should be a sharp near-pointlike imagery, without any irregular spikes or rays shooting out of it. Small deviations from this ideal image (figure 2) are always present in most binoculars (especially those with smaller apertures) and this is perfectly okay as long as the star remains a round disk even when moved towards the edge of the field.