Binoculars Guide – Test Before Buying
After buying your binoculars at a store, you should check their performance, or if you buy it online, as soon as they arrive, you should also check their performance as well. Below are few tests that will help you choose quality binoculars.
- Observe the objective lens carefully. if there are signs of scratches or dirt, you should reject that binocular.
- Check the weight if the binocular. Heavier instruments will be more tiring to hold than lightweight ones. It is better to go for the lighter models.
- How sound is the instrument made? Take it up and move the halves back and forth. The hinges should work smoothly, with steady resistance. Return it and try another if there is any play in the joints or any rattling.
- Try to hold the binoculars away from you at arm’s length, and point them at a window or the sky. The exit pupil should be truly circular and uniformly bright.
- It may take several minutes of usage and testing before you can detect collimation problems in some binoculars, but if after those minutes you feel your eyes uncomfortable as they compensate for the barrel misalignment, it probably means the binoculars are out of collimation, which means that the two barrels don’t point in the same direction. You should not take such binoculars because that is a serious problem.
- Find a high-contrast object like a tree, take up the binocular and look through it at the tree against the daytime sky, and place it in the center of the field. If there are strong green or violet fringes of light along the edges of the object, then the binocular is probably suffering from a defect known as chromatic aberration. This may not be much of a problem if it is for astronomical use, but it can be a real problem for birdwatchers and other nature enthusiasts who would want to get accurate color rendition.
- You can know the type of antireflection coatings by looking at the two reflections of the light from the back and front of the objective lenses. Green or purple reflections means it is multicoated lenses, while blue reflections means it is a simple coated lenses. Avoid binoculars that give bright white reflections; they will not perform well for astronomical use because they have no antireflection coatings.
- When you choose binoculars with a large field of view, you are likely to notice that the edges of the field are conspicuously distorted. This is an optical defect known as distortion and it is most obvious when used during daytime. This distortion is present even in high quality binoculars to some degree, but it is not easily noticed, especially in astronomical viewing.
- Taking your binocular outside at night to look at a bright star is the ultimate test for your best night vision binocular. Fter having the star centered in the field of view and the binocular is brought in a good focus, then take a close look at the star. The star should be as sharp near-point like imagery, without any irregular spikes or rays shooting out of it. To some degree, small deviations are present in this ideal image in most binoculars, and this is perfectly normal as long as the star remains a round disk, even when moved towards the edge of the field.
- Finally, remember that what you pay for is always what you get. In most cases the brand name speaks of the quality of the instrument, so beware of buying from companies with which you aren’t familiar with this.