Choosing Your First Binoculars

Kent Marts and Dan George talk about how to choose your first pair of binoculars for birding. This is an excerpt from the video Warblers & Choosing Your First Binoculars - On The Wing Explore Alliance MENTOR.

 

 

Transcript: we're going to talk about buying binoculars and if anybody's ever looked at binoculars
you always see numbers seven by thirty five eight and a half eight point five by twenty six
eight by forty two ten by fifty the first step in understanding binoculars is understanding these
numbers what in the heck do all those numbers mean and so we're going to tell you the first
number is the magnification power so if your eyeball uh
ed gunther's mark 1 eyeball is zero power so it's magnified seven
times if you're looking at a seven by thirty five the second number is the diameter of the
objective lens in millimeters and so what you learn is
make that quick ringing so the things to remember are the larger the diameter of the objective lens
the more light is gathered and squished down and go into your eye and if the magnification is the same
then the image will appear brighter so if you have a
8 by 42 and then an 8 by 50 then the 8 by 50 is going to appear to
be brighter because you get a bigger round circle that squishes down the light into your
eye and binoculars are just like telescopes they effectively
other than having magnification make the diameter of your pupil
the diameter of the telescope so imagine if like an owl and al's pupils
get real big same with yours your pupils get so big but now if you can make your pupils
7 by 35 suddenly you're getting a whole lot more light into your eye
and you can see better and see more detail because of the magnification uh dan anything you want to weigh in on
there yeah set the first number indicates it's of course as as kent said it's the
power of the eyepiece lens and what that what that means is of the
fact that what you are looking at is something that will appear to be seven times closer to you than the
human eye so it's not seven times bigger it's actually it makes the image look like
it's seven times closer to you because you're looking through seven power
and then the 35 as kent said is the size of the outside lens the objective lens
and that enables you to get more light into your eye to give you a brighter image
you can actually measure the little the amount of light coming into your eye by dividing the 35 by the seven so seven to
the 35 is five so that means the the middle in millimeters the little exit pupil it's
called is is five five millimeters uh women
that's right yeah yeah yeah you're right that's what it is i didn't get into the higher math but that number can be
important because if you know the diameter of your pupil
then that gives you an idea of how one it's going to be the bigger that that
number the easier it's going to be to finally get into your eye and number two
if you're you know your pupil is a certain size and all that light's going into your eye it's going to also make it
appear to be brighter so um also i'll add one thing
one reason why seven or eight power is the most popular is because the human
body can actually handle seven or eight seven power without any tremor without any of
your hands because your your heart's beating so believe it or not if you try to stand still looking through a
telescope for example you're not going to be able to you're not going to be able to look through there unless you're on a tripod
but with a pair of binoculars seven power is the power that you're that a human body can take without having
the unwanted tremoring yeah so and and like dan said every time your heart beats
your hands move a little bit you don't realize it but they do and so in astronomy world 10
by 50 is sort of the starting size and the trick i've learned is and i can
show you here with this cap on you put on top of the speakers where you say the same thing one thing i do
whether i'm looking at birds or looking at um use them for astronomy i will take the
binoculars like this and then grab onto the bill of my cap
and hold the binoculars like that and it's a snap back or fitted cap
locking the binoculars to the cap also locks it to your head and so you can steady your hands even
more by using that little trick whether for birding or sports or
astronomy as well that's a great that's a great suggestion kent thank you that's great you know ever every little bit of
reducing vibration and shake makes what you're looking at look better
and you're always on that quest for that so if one of the our watchers or our fans
right now were to say i've got an 8 by 42 and then some guy comes to you and says
well look i got a 10 by 50. okay he thinks he's got he thinks he's
got the best one for him because it's got a greater power but guess what what if you if he wants
to look at a bird on a limb he can't hold it still enough without a tripod
or they come up with a 20 by 80s or 20 by 100s boy look at these
yeah you can't and those things are so big and so heavy yes you can hand hold them for a few seconds
but it becomes serious work really quick and you just can't hold them still all right so there's two
distinct types of binoculars out there and these are both magnaview 8x42s
roof prism which is the one on the left this pair happens to be fully
multi-coated and there's all sorts of different you know fully coated fully multi-coated
on and on a quick primer on that fully coated means the front elements
and back elements are coated fully multi-coated means the surfaces are all coated um
inside and out the one on the left because of how they're made they're water resistant
so you can get them dewy and damp and foggy and they'll be okay
though the ones on the right which are poro prism so they have this this
standard traditional zigzag in the barrel of the binoculars
are uh called poro prism and this model are not water resistant
interestingly enough the close focus on the this pair of poro prism is 12 feet
whereas the close focus on the uh one on the left is 19.6 feet and that
that close focus distance sometimes does come into play in the birder world doesn't it dan
absolutely why well because uh you might be in a place
where you're trying to be pretty quiet and all of a sudden a bird comes towards you and lands eight feet
away most binoculars would require you to make noise by stepping back about one or
two yards so that you can you can get it into focus but with the binoculars designed i know
that you have some binoculars that actually are inside of 10 feet those would be preferable for the
burning for the burning world but for the astronomy world nobody cares about close focus correct for the birders
there's even some binoculars that have five or six feet yeah very special because of that specialized
use you know and you you think well why would i want to look at a bird that was six feet from me
because you really want to look at those details right on right you know a bird six feet away that's
magnified seven times is is is you're going to get really good
detail in what you're looking at can really bear down whereas a bird that's
35 yards away still is a very small little bird hard to pick out this is
that i ring all the way around or is it partial on top and on bottom and it's in the shade what color is that
rump really or the wing bar really so um but you know i've i've showed 42's here
there is a more common
you know the really preferred size is an 8 by 35.
right dan or a 7 by 35 here yeah we can't get lost in the numbers
necessarily but kent is correct uh you can still hold an eight power without hand tremor but that's why the human
body can handle seven power so you know the common i think the most popular
specifications for a binocular generally is seven by thirty five with the five millimeter
um exit pupil this one here is just just give you a little more power just
to eight power and you still have a little a little less than five uh five millimeters of of exit pupil yeah
four point three i just did the math real quick four point three so quick dude man but look at the close focus on
that yeah six point five feet that's exactly what you're doing which
which is this pair of binoculars right here i've got and you know they're fully fully
fully multi-colored they're face coated waterproof they're this open bridge design which makes them really easy to
hold they're really light uh just a beautiful pair of binoculars
so the the point is you know just like if you're building a house
there's specialized hammers you can roof a house with a framing hammer and you can frame with a roofing hammer
but using the proper tool makes life a whole lot easier for you and so if you're going to be out birding
you know 7 by 35 6 and a half by 35 8 by 35
is that you know really primo sweet spot and especially if you can get close
focus down that six seven eight foot range
so what dan what's your favorite pair seven by thirty five no my favorite pair is
eight by 42 about 42. why um mainly because
um it has at least five millimeters of exit pupil
and uh also it's not so heavy that you can't hold it because you get a 10 if you get a 10 power
magnification no not magnification but it but a 50 millimeter objective lens
that that gets to be pretty heavy over the course of using it in the field
but 42 millimeters just has turned out to be the most common uh contrast from a
seven to a ten eight eight power seems to be it