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Optical Hardware | FAQ's
- Freqently asked questions
The page below gives answers to the common questions we are asked and we are adding to it all the time. We get some many questions about digiscoping, we have created a special digiscoping FAQ page so if your question is about DIGISCOPING please click here.
All other questions are covered below.
1/ How important is magnification
?
The first number on a binocular
indicates the power or magnification. An 8x40 indicates a magnification
of 8x, so whatever you are looking at appears to be 8x closer or
bigger. One of the biggest mistakes in choosing a binocular is to
select too much magnification. Although a bigger magnification makes
the scene appear much closer, there are disadvantages. Bigger magnifications
are harder to hold, so the image is shaky, and larger magnifications
produce much narrower field of view, so although you see things
closer, you see less of it making it harder to view.
Higher magnification uses more
light, so a highly magnified image will not be so bright, on balance,
it’s important to select a magnification which is right for the
job.
For more detailed information check out our technical guide, or our more detailed technical guide
2/ What does Ocular diameter mean ?
The OCULAR
means eyepiece ( nearest the eye ) so the diameter of the ocular is just the
actual diameter of the glass on the eyepiece lens. Larger
diameter eyepieces ( like those on the Visionary HD ) improve quality of viewing.But, many
users get this confused with the diameter
of the exit pupil. The
diameter of the exit pupil is the bright
circle in the middle of the eyepiece. This is related to the
magnification and size of the objective, and is roughly the objective diameter
divided by magnification, so a 7x50 produces an exit pupil of (50/7) = 7mm and
a 20x50 is (50/20) = 2.5mm. A bigger
exit pupil makes the binocular brighter in low light conditions. The human
eye pupil opens up in low light and closes down in bright light, so, on a
bright day it doesn't matter if the exit pupil of the binocular is small,
because the eye pupil is small. A 20x50 etc, will work perfectly well
on a bright day.
In low
light, where the eye pupil opens up, binoculars with larger exit pupils perform
better.
BUT, the
maximum pupil diameter of the eye is about 7mm, so there's no point in having a
binocular with an exit pupil bigger than 7mm, because the eye can't use it. With this
in mind the optimum binocular for low light is a 7x50 or 8x56 or 9x63 or 10x70
etc.. There is
another small but ... as we get older the ability of our eye pupil to open
reduces and some users may not see a significant difference in low light
performance between an 8x40 or 10x50 ( exit pupil 5mm ) and 7x50 or 8x56 ( exit
pupil 7mm )
For more detailed information check out our technical guide, or our more detailed technical guide
3/ What does field of
view mean ?
Most binoculars indicate an angle
of view, either shown in degrees, or expressed as a number like
100m at 1000m. A
wider angle means you see more of the scene you are looking at.
Usually wider
angles are found on lower magnification binoculars, an 8x should
have a field of view between 6 to 8 degrees, but a 12x is likely
to be only 4-5 degrees.
For more detailed information check out our technical guide, or our more detailed technical guide
4/ Are there any telescopes which are equally good for astronomy and bird watching
Tricky
question that one because astronomy and birdwatching are totally different.The brief
answer is yes a spotting scope with a large front lens can be used for
both but I've given some more detailed thoughts below. I'd suggest
minimum of 80mm objective, so from our range of spotting scopes the following
models would be OK,
Visionary
V80 ( 20-60x80 ) Visionary
80ED ( 20-60x80 ) Illusion
i100 ( 25-75x100 ) Olivon T80
( 20-60x80 )
Olivon
T90 ( 23-68x90 ) Olivon
T80ED ( 20-60x80 ) Olivon
T90ED ( 23-68x90 )
Now the
more complete answer :
Telescopes
primarily designed for astronomy ( astroscopes ) tend be differently designed
to those for normal terrestrial spotting ( birdwatching etc ) For astronomy
it's important to have really good light gathering and quite high
magnifications can be needed to see detail in distant objects. It's not so
important on an astroscope to have close focusing, and usually astroscopes
produce upside down images. ( when looking at things in the sky it doesn't
matter which is up and down ) Also the tripods on astronomical telescopes
are often of "equatorial" design, this means that they don't have the
usual ( side to side / up and down )head movement, instead the head tracks
in an arc to allow for the movement of the earth. This type of tripod mount is
great for astronomy but quite awkward for birdwatching. A normal tripod for
birdwatching would be a bit slower to use for astronomy.
Other
considerations are that good astronomical telescopes can be quite expensive,
you really need something with an 6 inch ( 150mm ) objective lens or mirror (
some astroscopes use mirrors instead of lenses ) to get any decent light
gathering, better still 8 inch or 10 inch, and a good solid tripod. Also
atroscopes tend not to be water resistant ( you'd never use an astroscope in
the rain because there would be nothing to see )
Now, having
said all this, for basic astronomy ( looking at the moon, planets, odd comet
etc etc ) you can get away with a smaller scope. There are quite a lot of
astroscopes on the market with smaller lenses or mirrors, 76mm and 114mm are
quite popular and not expensive and these will be OK. But even so, these
will probably have equatorial mount tripods and give an upside-down image
so they are not so good for birdwatching.
A normal
spotting scope ( like the Visionary V-series, Olivons or Illusion i-series
) produce clear, bright and normal upright images, are well colour
balanced for nature viewing, they have more rugged body designs and
waterproof. They attach to normal tripods allowing quick easy finding of
subjects. ....
and, most importantly, a spotting scope with a good sized front objective will
be at least as bright as it's equivalent sized astroscope, and most of
them have zoom eyepieces which get up to the same sort of magnification that
you could achieve with an astroscope. In fact sometimes spotting scopes can be
brighter because the mirror designs of many astroscopes don't use the full size
of the mirror to gather light
Because of
this, for basic astronomy, a spotting scope of 80mm or above will work very
well indeed.
For more detailed information check out our technical guide, or our more detailed technical guide
5/ Does "waterproof and nitrogen filled" mean that a binocular or scope is FOGPROOF and is waterproofing covered under guarantee
The
expression 'fogproof' is often misused these days so we don't use it quite so
much in our publicity material, but basically any fully waterproof and nitrogen
( or equivalent ) filled instrument should dramatically reduce condensation on
the internal optical elements.
It isn't
possible to seal instruments forever, there will always be some leakage of the
dry gas so it is necessary to recharge this if you wish to keep the instrument
waterproof. This isn't covered under guarantee as it's normal usage. Also,
please note that with any instrument with interchangeable lenses ( which
includes most scopes) you can' fully seal the section around the
eyepiece so there may be some fogging here which should clear quickly.
6/ Do any Optical hardware
models ‘see in the dark’
Yes some of our models work in very low light, but don’t confuse night vision
scopes with low light binoculars. A night vision scope is designed to work with little
or no light and provide an image, These are black and white ( or
more usually green ), low magnification and cannot be used in daylight
A low light
working binocular will work during normal daylight as well as in
low light levels, and with more realistic magnifications, however
lowest light level is moonlight or equivalent.
7/ Does Optical Hardware
supply directly to the public ?
No, but we will always
help you find a dealer.
8/ I’m a teacher and want
to buy a large number of binoculars for class use, can I buy directly from you?
Yes, we can supply schools and colleges directly so long as this is via an official purchase order. There will be discounts for quantity, however it may still be cheaper to buy through one of our dealers. For small quantities we would suggest you purchase via one of our dealers
We can advise best models to suit
your needs and budget, and orders can be placed on a school or local
authority purchase order, or by cheque or credit card if you prefer.
9/ What's the difference between waterproof and water resistant and weatherproof?
Weatherproof and water resistant are really the same thing.
A waterproof binocular is designed to withstand submerging in water, whereas a water resistant/weatherproof will stand rain, but not depth of water under pressure. All Optical Hardware/Visionary/illusion models conform to these definitions - if we say waterproof, it can be submerged, if we say weatherproof, it can held in the rain, but not submerged. Unfortunately, there is no industry standard on this definition, some manufacturers and brands use the word waterproof to mean that iit will withstand rain, by our standards this is only water resistant.
10/ How waterproof is "waterproof"
By waterproof we mean it can be submerged in water, but this doesn't mean it can stay underwater for a long period, water pressure will eventually force water into a waterproof binocular. The better the binocular is constructed, the longer and/or deeper the binocular can be held underwater. binoculars built to military specifications can usually withstand a depth of about a meter for up to fifteen minutes ( enough to allow wading through deep water with a binocular in a waist bag.) A basic waterproof, would only stand a few cm of water for a minute or so ( enough to rescue it if dropped in a shallow stream ) Most waterproof binoculars are also "nitrogen filled" This means that there is a dry gas inside which prevents the binocular misting on the inside in low temperatures and damp conditions. Eventually however this will leak out, so a nitrogen filled binocular will not remain filled. They can be recharged, but this is often costly and for lower price binoculars it probably isn't worthwhile, the binocular will still work perfectly well under normal conditions. See question 5 above. It's worth bearing in mind that there is no industry standard on this definition, some other use the say their binoculars are waterproof but by our standards this is only water resistant.
11/ I want an Olivon hide-clamp but I'm confused a, you list a "clamp" but this seams only to be G-cramp, not a full useable tool for my telescope, other manufacturers sell the complete unit. Can you advise ?
The Olivon can be bought as a complete unit ready to use, or you can buy parts and sections to tailor the unit to your exact needs.
You require : clamp + column + head.
The clamp is the basic part wihich fixes to the table. The column fits into the clamp and slides up and down to the selected height. The head fits on top of the column and allows the binocular or scope to be moved up/down and side to side.
We supply columns is two lengths 23cm (short ) and 45cm (long)
All the Olivon heads will fit, though for a hide clamp the most useful or the TRH-11 and TRB-14. If you wish to buy a reay to use hide clamp we suggest clamp+ column L + TRH-11 head or for the more adventurous users clamp + column L + TRB-14 head. Most of our stockists will be be able to supply these eady to use.
More information about the OLivon Hide-clamp, click here
If you already have an Olivon TR-154 or TR-159 tripod, then your centre column and head can be used and you only require the clamp section.
For questions about digiscoping, click here.
Click here for our stockists if you don’t have a stockist
locally,
or can’t find what you want, give us a call
ask a question ? - click here
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