Types of optics
Binoculars or monoculars?
The question is typically one of convenience. Monoculars, being only a single barrell, are more compact, lightweight and therefore easy to pack along than an equivalent set of binoculars.Some studies have shown that b Binoculars, however, provide better depth perception and viewing acuity than monoculars due to having both eyes involved.
So, if you need to watch &/or study an object or critter from a distance, for any length of time, binoculars would be the recommended optic. If you need to simply locate & identify, then monoculars will do the job more efficiently.
What about spotting scopes?
Spotting scopes fall into the range in between binoculars/monoculars & telescopes. They typically provide additional magnification for far-off subjects, and can often accommodate digital cameras and other recording devices. Although easily portable, their size & weight means that they are typically used for field study.
Glass & Coatings
You get what you pay for...
Sports optics typically use one of three types of prism glass: BK-7, BaK-4, & SF. Generally, the most inexpensive optics use BK-7 glass. You may notice halos, slight aberrations in the image, & often edge distortion. Most quality optics use BaK-4 or low-dispersion Fluorite glass. These types offer crisper images with practically zero distortion & better light transmission. Of course, like everything else, the better the glass, the more expensive the binocular or scope.
Lens surface shaping & lens coatings assist in keeping an image from becoming distored under varying light conditions & at its edges. Different wavelengths of light are affected differently by lenses & prisms, so special coatings help minimize this effect. 'Coated' & 'multi-coated' lenses are better than most, but often only coat some of the lenses, or only certain sides. Look for 'full multi-coated' lenses & prisms to be assured of the sharpest & brightest images.
Comparing Performance
What do the numbers mean?
In order to choose the right set of optics for you, and to get the most out of them, it is important to understand the numbers associated with them.
Magnification
This is simply how much larger objects will appear through the optic than they will with your bare eyes. When you see a set of binoculars with the numbers "7x50", the first number "7" refers to the magnification.
Objective Lens
This is the second number in an optic's specification number. It refers to the diameter in millimeters (mm) of the large lens at the front (object) side of the optic. In the case of "7x50", this would refer to a 50mm lens.
Exit Pupil
This is a ratio of the objective lens to the magnification, and refers to the size of the disk of light that exits the optic into your eye. The larger the exit pupil number, the brighter the image will appear. A number larger than 5 is considered bright, while anything under 3 is best suited for daylight use. Our example of "7x50" offers an exit pupil of 7.14, while an 8x32 optic offers an exit pupil of 4.
Close Focus
This is a mechanical number that refers to how close the optic can be to an object and still bring it into focus.
Field of View
This is a reference to how wide an image you can view with an object. It is usually referenced to 1,000 yards for easy comparison between models.
Eye Relief
This refers to the ability of the optic to accommodate users who may use eyeglasses. When using eyeglasses, the eyecup rests against the glasses lens and not against the ridge of the eye socket. Optics with Eye Relief are able to focus an image further away from the eyepiece. |
Epoch Compact
