Sunday, November 9, 2014

Emergency Preparation, Part 19: Seeing what's coming at you


One aspect of emergency preparation and 'bugging out' that's seldom discussed is the need to see at a distance.  I mentioned binoculars in the ninth article in this series, 'The Vehicle Emergency Kit'.  There are many situations in which they may be very useful.

  • If you're on the road, they help to spot traffic jams or backups before you get to them.  Give them to a passenger to look ahead from hilltops.  Are there other roads visible that bypass or go around the blockage?  Can you get to them from your present position, before you reach it?  A good navigator equipped with a pair of binoculars can be very useful.
  • In an unsettled situation, impromptu roadblocks might be set up by locals trying to stop an influx of outsiders wanting to share what they've got;  or criminals might set them up to rob travelers.  Can you see such a roadblock in the distance?  Who's manning it?  What sort of behavior is visible on their part, and/or from travelers?  Are vehicles being pulled off the road and made to park?  If so, you may want to avoid getting too close to whatever's going on there.
  • In some states (e.g. Louisiana), in a weather emergency authorities institute contraflow lane reversal to speed up evacuation.  This might directly impact your travel, as the lanes you're using might suddenly be 'cut off' from further progress in the direction you want to go.  If you can see that happening before you get to it, you may be able to get off your present road onto one that will allow you to move forward.
  • If you're looking for food, shelter, fuel, etc., are there locations ahead that might prove fruitful?  They could include gas stations, highway rest areas, woods where deer or other game animals might be found, farms where you might be able to buy or trade for food, potential camp sites, water sources, etc.
  • If you establish a camp for yourself and your family, it helps to be able to see details of who's approaching before they get too close.  This might give you advance warning that their intentions may not be peaceful.

Those are only a few of the situations where being able to see clearly at a distance might be not only useful, but potentially life-saving.  There's also the entertainment value to keep kids distracted while driving, which is not a small consideration for their parents' sanity!  Finally, a pair of binoculars is useful for many everyday activities like sports, bird-watching, hiking, etc.  They're not just for emergencies.

It used to be the case that a good pair of binoculars would cost a great deal of money.  That's no longer true, although you do have to pay a moderate amount for a worthwhile set.  In general terms, you should be able to get a decent pair of compact (i.e. pocket-size) binoculars for $50-$150, and a good pair of general-use binoculars for $150-$250.  Below those figures there are still perfectly usable optics to be had, but they usually come with limitations and reliability issues.  Of course, if you have the money, you can buy a Swarovski or Zeiss unit costing thousands of dollars . . . but they're beyond the reach of most of us.



Vanguard Endeavor ED 8x42mm (see below)


There are four primary characteristics to consider when thinking about binoculars.


1.  Weight and size:  In general terms, bigger (i.e. larger-diameter) lenses allow more light to pass through, can be more precisely ground in optical terms than smaller ones, and offer the best performance across the board.  However, they also require larger barrels (the part of the binocular containing them) and more space between the various lenses for focusing purposes.  That's why a 50mm or larger objective lens (i.e. the front, light- and picture-gathering lens) typically comes in a relatively bulky, heavy pair of binoculars.  A 42mm objective lens, which has become the mid-range standard, comes in binoculars that are somewhat smaller and lighter;  and a 21-32mm objective lens is usually found in pocket-size binoculars.

Generally, the bigger the lens, the more precisely it can be ground and the more light it admits.  You'll find that at dusk and in low light, a set of pocket-size binoculars will become unusable some time before larger units for that reason.  On the other hand, the smaller binoculars are lighter and easier to carry around than bigger units.  Your selection will be a trade-off between ease of carry and optical performance.



Nikon 8208 Oceanpro 7x50mm Marine Binoculars with compass


2.  Magnification:  Bigger is not always better.  Common magnifications are 8x, 10x and 12x.  There are 'zoom' binoculars available, offering variable magnification;  but I generally don't recommend them because the additional complexity of their lens structure cuts down on the amount of light they admit (see the discussion of 'exit pupil' below).

The higher the magnification, the lower the field of view (i.e. the distance from left to right, or top to bottom, that you can see when looking through the binoculars).  For example, the Bushnell Legend Ultra HD 8x42mm binocular has a field of view of 426 feet at 1,000 yards, while its more powerful cousin, the Legend Ultra HD 10x42mm, has a field of view of 340 feet at the same distance.  In exchange for 25% more magnification, the latter binoculars impose a reduction in field of view of more than 20%.  That trade-off is significant, and gets worse with higher magnifications.  It depends on the individual user to decide what's acceptable;  but the less your field of view, the more difficult it becomes to pick up distant objects with your binoculars, particularly if you're in motion (i.e. in a vehicle or on a boat) and don't have a steady platform.

In general terms, the higher the magnification, the harder it will be to hold your binoculars steady on what you're trying to view.  Select a magnification sufficient for, but not greater than your needs.  I usually find 8x-10x powerful enough.


3.  Exit pupil:  This is calculated by dividing the diameter (in millimeters) of the objective lens by the magnification of the binoculars.  Some typical examples for common binocular sizes are:

8x25mm = exit pupil of 3.125
10x25mm = 2.5
12x25mm = 2.083

8x42mm = 5.25
10x42mm = 4.2
12x42mm = 3.5

7x50mm = 7.14
8x50mm = 6.25
10x50mm = 5
12x50mm = 4.16

The higher the exit pupil, the greater the light transmitted through the binoculars to the eye.  That's why the 7x50mm size (such as, for example, the Nikon Oceanpro model shown above) has dominated the marine binocular market for many decades - it offers sufficient magnification for common needs, plus the greatest possible light transmission for night-time use (so much so that they're often referred to as 'night glasses').  Wikipedia explains the exit pupil with reference to binoculars as follows:

Since the eye's pupil varies in diameter with viewing conditions, the ideal exit pupil diameter depends on the application ... A set of 7×50 binoculars has an exit pupil just over 7 mm, which corresponds to the average pupil size of a youthful dark-adapted human eye in circumstances with no extraneous light. The emergent light at the eyepiece then fills the eye's pupil, meaning no loss of brightness at night due to using such binoculars (assuming perfect transmission). In daylight, when the eye's pupil is only 4 mm in diameter, over half the light will be blocked by the iris and will not reach the retina. However, the loss of light in the daytime is generally not significant since there is so much light to start with. By contrast, 8×32 binoculars, often sold with emphasis on their compactness, have an exit pupil of only 4 mm. That is sufficient to fill a typical daytime eye pupil, making these binoculars better suited to daytime than night-time use. The maximum pupil size of a human eye is typically 5–9 mm for individuals below 25 years old, and decreases slowly with age after that.

There's more at the link.

If light transmission is important to you (for example, if you hunt or bird-watch at dawn or dusk, and need to see animals moving in low light conditions), you need binoculars with the highest possible exit pupil ratio, even at the expense of lower magnification or higher weight.



Bushnell Legend Ultra HD 10x42mm (see below)


4.  Dust-, fog- and waterproofing:  If you expect to use your binoculars in damp and/or dusty conditions, you need a unit with at least some weatherproofing.  Cheap binoculars will admit dust and moisture, which will eventually obscure their optics.  More expensive binoculars can be had with a greater or lesser degree of weatherproofing, including a rubber coating to make them more resistant to shocks (i.e. being dropped) and more waterproof.


There are numerous other factors to consider when choosing binoculars:

  • The presence of range-finding reticles or compasses, if required;
  • Image stabilization (critical for higher-magnification binoculars);
  • Type of focus (fixed, center, etc.);
  • Type of optical construction (roof prism, porro prism, etc.);
  • The ability to take a digital photograph through the lenses;
  • Eye relief (important if you wear spectacles);

and other issues.  However, the four described above in detail are the most important, IMHO.  You should first narrow down your choices in those factors to an optimum combination, and only then choose the pair of binoculars that best fits that profile and meets your requirements in terms of the 'minor' factors.

Here's what I use and recommend.  Of course, there are many other choices.

Primary units:  I recommend the Bushnell Legend Ultra HD 10x42mm (shown above), the Nikon ProStaff 7S 10x42mm, and the Vanguard Endeavor ED 8x42mm (also shown above).  All three are reasonably priced for the performance they deliver.  Over time I've acquired one of each, using the 10x's in broad daylight or when I want a little extra magnification, and the 8x when low light may be a factor.  If I have to choose only one, I'll take the 8x Vanguard unit for its larger exit pupil and light-gathering power, or one of its equivalents from Bushnell or Nikon.  If frequent use in very low light or at night was on the cards I'd buy the best 7x50mm unit I could afford (preferably a marine version for its weatherproof qualities), even at the expense of greater weight and bulk.

Pocket units:  Due to limited light transmission through such small lenses and barrels, I don't recommend going above 8x magnification in pocket units.  Among units I've personally liked are the Bushnell Trophy XLT 8x32mm (shown below), the Leupold Rogue 8x25mm, the Olympus Tracker 8x25 and - albeit rather more expensive - the Steiner 2210 8x22mm Safari UltraSharp unit (also shown below).  If I have to choose only one, it'll be the Bushnell thanks to its larger exit pupil ratio (i.e. better light transmission), protective rubber coating, and affordable cost.  It's less compact than the others, but I think the combination of its other advantages outweighs that.  For absolute ease of portability at the expense of all other factors, while still offering relatively good optical performance, the Steiner takes the crown.



Bushnell Trophy XLT 8x32mm (see above)



Steiner 2210 8x22mm Safari UltraSharp (see above)


(It may seem odd considering my emphasis on quality, but I also have in my emergency reserves several pairs of cheap Tasco Essentials 8x21mm pocket binoculars.  I leave one in my car emergency kit, and have a few extras on hand.  I paid less than $10 apiece for them, so I can afford to break or lose them;  and in emergency they may be needed by friends, or make useful trade items.  Their quality isn't great, but it's a darn sight better than nothing!)

If you'd like additional information, Chuck Hawks has a good 'binocular basics' article.  As for what to buy, over and above what I've suggested, here are the 2014 winners of Binoculars.com's annual awards.  (Note that some of them are VERY expensive!)  Also, Amazon.com has a useful list of the compact binoculars highest-rated by its customers.  I think you'll be well served by any of the units in either list.

(EDITED TO ADD:  As the first commenter below points out, DO NOT USE A RIFLESCOPE MOUNTED ON A RIFLE AS A SUBSTITUTE FOR BINOCULARS!!!  Far too many hunters idiots scan the countryside through their riflescopes.  As the commenter notes, if anyone in his right mind sees someone aiming a rifle at him [because that's precisely what it is, even if the other party doesn't intend to shoot], he's going to take very strong action indeed, on the [entirely legitimate] grounds that he has to stop the threat before a shot can be fired at him.  I'd certainly do that!  Binoculars [or a monocular] don't offer the same visual threat.)

Peter

EDITED TO ADD:  In response to reader questions, I've written a follow-up article on the best low-cost compact binoculars out there at the time of writing.  I've also put up a video clip showing how binoculars are made.  Click the links to go there.

10 comments:

Inconsiderate Bastard said...

Very worthwhile post, Peter.

I'd suggest also considering monoculars. I keep a Vanguard 8X25 monocular in a pocket of my "shoot me first" vest because it's about 1.25 inches in diameter, 4 inches long, weighs 4 ounces and was about $40 during an online deal (I bought 3, so usually there's one within reach). It's proved quite handy, and I've even used it for spotting paper targets out to about 75 yards (beyond that more magnification is needed to see the holes). Barska makes a 10X40 monocular that turns up on sale online sometimes for under $50; it's bigger, so not as "pocket friendly" as the smaller Vanguard, but much better at light gathering.

Longer, so not as useful, is an old rifle scope. Many shooters have an old 3X9 scope somewhere in our kit that, for whatever reason, isn't on a rifle. Those can be handy monoculars as well.

A word about using rifle scopes - DO NOT USE A RIFLE SCOPE FOR DISTANCE VIEWING WHILE IT IS MOUNTED ON A RIFLE. Some hunters, and I'll call them the Really Stupid ones, think it perfectly OK to "glass an area" for game using their mounted rifle scope. By definition, while they are "glassing an area" their rifle is pointed at whatever they are looking at.

If you're one of these Stupid Hunters, I don't care that your rifle is unloaded (it probably isn't, and see Rule #1), I don't care that you're looking at "distances so far away that you wouldn't take a shot anyway," or any other excuse you might dream up.

What I will see is a person with a rifle shouldered in a shooting position aiming that rifle at me. I will consider that a direct and immediate threat and treat it as such. You will not enjoy what happens next.

Peter said...

@I.B.: Excellent point, thank you. I should have thought to include it myself. I've incorporated it as a note in the main body of the post.

Old NFO said...

IB is right, and idjits DO it all the time... sigh

Graybeard said...

If I may point out one thing, exit pupil tends to get smaller (worse) with age. You noted the Wiki discussion says "average pupil size of a youthful dark-adapted human eye".

Having an exit pupil larger than your pupil isn't a bad thing, it just means some of your aperture is wasted. Your 7x50s perform the same as a 7 x42 or x35 or so. Since aperture is expensive, us older folks can save money by going for smaller aperture binoculars without losing performance.

Anonymous said...

If things go bad enough that "hasty roadblocks" to relive you of your possessions have become a reality, then the ones manning them will most likely have uniforms and at least some implied "governmental authority". They will most likely have the exits blocked,(police and military SOP) and will be ready to act with overwhelming violence with little provocation. At that point you must abandon your transport and flee on foot, or stand a 50/50 chance of becoming a lump in a mass grave, as Dead men tell no tails. Your only other option is to form up an "assault force" and fight through. Not a very good choice unless your "force" significantly outnumbers there's. --Ray

Peter said...

@Graybeard: You're right, but what if there are younger people in your party who might need them? Their sharper eyes will be better served by a greater exit pupil ratio, while our older eyes won't be hurt by it. I do agree, though: at my age, an 8x42 unit gives me as much night vision capability as I'm going to get.

Anonymous said...

I'm a bit of an optics geek, having built a number of telescopes in my time and teaching physics for a living. I've got to say, your post is mostly spot on. Over the years, I've owned dozens of pairs of binos, and my own recommendations would have to include the Nikon Monarchs, which are my go-to choice in 8x42. The amazing thing to me is just how good cheap ($60+) binoculars have gotten in the past ten years or so, especially when you go with reputable brands.. As far as the compacts are concerned, however, I stick with porro prism designs over roofs. An example would be my Pentax 8x25 ucf's. In the smaller sizes the alignment and coating of the porro prisms is not as critical as for roof prisms in order to get good performance.

Proftel said...

Want to know how to get out quickly in an emergency?
This video was taken in Rio de Janeiro, worth watching on the big screen:

https://www.youtube.com/watch?v=9QYrtXxE9ls

:-)

ZerCool said...

A big plus-one for the Bushnell Trophy XLTs. I use a set of the 8x42s for ... well, nearly everything. Stars/moon. Hunting. Range. Etc.

Able said...

Interesting!

I admit to being a gear addict so have a nice pair of Steiner Navigators (which may have been acquired by being 'lost' on a long ago op) but for daily carry I use a cheap n' cheerful Opticron Trailfinder II 10x25 monocular (decent enough performance, small and easily lost in a pocket, and cheap enough that I don't mind 'that' much if I lose/break it).

If I 'have' to see though (ageing eyes and all) I carry a Gray & Co. Stalking telescope (expensive I admit, but almost indestructible). It's about the same volume/weight as a decent pair of binoculars but is at a level of performance you have to see to believe (plus it allows me to vent my inner Hornblower when I must).

A decent collapsible telescope is an option to consider if you need performance in a portable package.