Bino buying - performance factors - long
I see some recurring questions and comments especially about binos, so I offer these comments for what they are worth to help and save you some headaches (literally). After birding for 15 years, doing bird census work, competing in tournaments, and leading groups of birders of many levels with every bino and spotting scope imaginable (and some that weren’t), here are some factors you might wish to consider in buying binos and spotting scopes.
Clarity – The picture should be as clear as a glass of drinking water. Some optics will appear to have a very light “haze” or “fog” or slight (or worse) whiteness to the image. With good binos one should be able to read headlines on a newspaper at 75 - 100 yds., and with some top models even farther. Check for image quality up close within 15 yards, beyond a 1000 yards, and multiple points in between. Low light visualization is important for a quality check, but so is bright, hot and hazy. Top glass has the ability to “cut” through humidity and reflected light, especially at longer distances, and visualize images incredibly far away, just as it can “improve” low light conditions.
Sharpness & Depth – compare image in the center of the field of view with the outer portions of the field of view. They should be equal or only of a slight difference. Also, consider the depth of the image. Does the image appear to have “depth” or is it “flat” in comparison to other models under consideration.
Color – one of the more subjective components but important. Some glasses tend to have a more green and blue appearance and others have a more red and brown tone. Try focusing on something near that you can easily view with your unaided eye. Compare the image with and without the optic to check for trueness of color in the optical image. Try this test on several images of different colors.
Ease on the eye – Look at an image continuously for 3 – 5 minutes, which is not unusual for a field use when really concentrating and observing something with binos or a spotting scope. Do your eyes tire or ache, or do your eyes feel like looking through the optics is enjoyable?
Focus & Alignment – Critical, critical, critical in binos. First, focus the barrel with the fixed eyepiece (i.e. not the one with the twisty adjustment on the eyepiece) with the other barrel blocked with a bino cap. Now, WITHOUT ADJUSTING THE FOCUS WHEEL block the barrel/eye you just focused and look through the one with the twisty/adjustable eyepiece. Twist the eyepiece until the image is in focus. For both adjustments take the binos down let your eyes rest, and then double check each. Once both barrels have been adjusted for each eye, look through both barrels simultaneously. Is the image identical, sharp and crisp, or do you see a blurry or double image? Try alternating closing eyes back and forth and the image should remain stable in the field of view. If not, the barrels may not be well aligned. Do not buy a brand new pair of binos that are not well aligned. They will give you headaches and leave you feeling google-eyed. Top end binos can be realigned later in their life if they are dropped or damaged (typically by compression in luggage) but there is no reason to start off life out of alignment.
Fit – How do the binos feel in your hand after holding them for 5 – 10 minutes continuously? Binos come in many shapes, sizes and exterior finishes. Which fit your hand? Which will feel good when your hands are hot and sweaty, it’s raining, or freezing cold and you need to use gloves? As an example, the top end Leicas of 10 years ago had a notorious hard, smooth plastic exterior case which was like grease when wet. Thankfully it has been corrected. Is the position of the focus wheel in an easy to use location that feels comfortable and natural to you? Is the focus wheel wide enough that you can focus with gloves on or if your fingers are cold and wet from rain?
Speed of focus - An important, and often overlooked, quality to consider for wildlife viewing.
Weight - Less is more especially later in the day.
Waterproofness - Waterproof optics have become the standard for mid- and top-tier optics. Optics that are not waterproof will fog internally – for field use, it’s not an if, just a when. Waterproof models can fail, but your odds are dramatically improved with waterproofness.
Price – There are three rough tiers of price. 50 – 150; 300 – 400; and 800+. The 50 – 150 tier are only for the most modest of uses – little league games and the like, and almost never of sufficient quality to endure long in field use. Poor barrel alignment is a frequent problem in this category. The mid-tier actually has some very well made, high quality products, which well serve the needs of most users even in some demanding field uses. The top tier is just that and there are some whose use requirements justify the price. The top tier usually will come with a warranty for the lifetime of the original purchaser. One pair of top tier binos will serve the user faithfully for many years of hard and the most demanding field use.
Hope this helps a bit.