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HOW
TO CHOOSE A MAGNIFIER
GO TO LARGE PRINT VERSION
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and see our recommendations, click here
CONTENTS OF THIS ARTICLE
Scroll down or click on these links:
Magnification,
Names, How to use
a Magnifier, Lighting, The
Rules and the Materials,
Magnification and Working
Distance, More Technical Stuff,
Quality and Price, Conclusion.
Appendix: Focal Length, Dioptres and Magnification,
Recommendations
OTHER ARTICLES
Jewellers
loupes compared, binocular
magnifiers compared
LARGE PRINT
SIZE
AND MAGNIFICATION
The size of a magnifier is given as two
figures, e.g. 10X18. The first figure is the magnification,
the second figure is the diameter of the lens in millimeters.
So 10X18 means that the magnification is 10X
(makes items appear ten times larger than normal) and the
lens size is 18mm diameter.
Sometime the lens is square. You will still see the magnification followed by the lens size, as above, but it will look something like this: 2X 80X80 (that would mean 2X magnification with a lens size of 80mm X 80mm.
Incidentally, exactly the same applies
to binoculars and telescopes, the 'diameter' being that
of the big lens (the objective lens) so a "7X50"
binocular or telescope has a magnification of 7X and objective
lens diameter(s) of 50mm.
Having grasped these basics, customers tend to ask: "What
is the most powerful (highest magnification) I can buy?"
And then, "What is the LARGEST lens with the highest
magnification?"
These are the wrong questions.
The questions should be, "What
magnification do I need?" and "How does the quality
(how clearly I will see) vary? - and is a powerful magnifier
as 'clear' as a less powerful magnified? - and are there
different types of magnifier?
MAGNIFIERS - THE
NAMES
Don't be embarrassed if you get the names
wrong, nearly everyone confuses a loupe
with an eyeglass,
most people refer to 'the flat magnifier' when they mean Fresnel,
or 'the thing you stick round your head' when they mean 'headband
magnifier'. Here are the true names.
Any magnifier large enough to read text
(e.g. newspapers, tins in a supermarket) is a 'reading
magnifier'. Some are large with plastic handles (I call them Readers), some
fold or slide into cases (I call them General Purpose Magnifiers), some are small
(30mm across), some are large (a few inches). One interesting
variation is the 'Fresnel' (pronounced Fren-nel because it's French), a flat sheet of magnifying plastic,
the size can be credit card size up to page-size. Whatever the technical name, these are
all 'reading magnifiers'.
A jeweller's loupe (pronounced 'loop')
is a small folding magnifier (from 12mm to 21mm diameter)
of high magnification (usually 10X or 20X) which folds into
a metal or plastic case. A watchmaker's eyeglass is a cone
of plastic, you hold the open end in your eye (it takes
practice!). The IDEA of a watchmaker's eyeglass is that
there's enough working distance to repair the watch, which
means that the magnification must be low (more about this
later).
As a guide to quality, both loupes and
eyeglasses start at at £2.00 but the best eyeglasses cost
£4.50 whereas a good quality loupe costs £20.00 and the
best quality £85.00 (quality is paramount when viewing gemstones
and diamonds or detecting the more 'difficult' forgeries
in stamps and coins).
Finally, hands-free magnifiers: there's
a the page-size lens that hangs
around the neck (good for reading, sewing, embroidery,
fly-tying, good value at £5.00); watchmakers eyeglasses you
hold in your eye (see above); various lenses that clip to
spectacles; binocular
headband magnifiers (includes a selection of clip-on
lenses and an adjustable light, £20.00).
Apart from deciding on the APPROXIMATE
magnification (2X or 10X) and APPROXIMATE size (pocket-size
or page-size) and APPROXIMATE quality (£2.00 or £20.00)
there is no rule about which type of magnifier to use. Some
professional engineers buy a the cheapest largest reading
magnifier because they don't like to spend money, some hobbyists
will spend £85.00 on a Zeiss 10X20 loupe simply because
they want the best and they can afford it.
HOW TO USE A MAGNIFIER
With a large magnifier (e.g. for reading
books, small print etc) hold the magnifier part way between
your eye and the object. Now move the magnifier very slowly
backwards and forwards until you have the best image, not
too small, not too fuzzy. The idea with a large reading
magnifier is to set up straight, sit comfortably, you should
not have to bend over the magnifier and peer closely (though
it depends on the quality of the lens).
With a strong magnifier (e.g. a jewellers
loupe) hold the magnifier as close to your eye as possible
(if you wear spectacles you may leave them on or take them
off, whichever is the most comfortable). Next, bring the
object very close to the magnifier, so close that it's almost
touching. Finally, very slowly move the object away until
it is in focus.
LIGHTING
Lighting is as important as magnification,
as important as quality, without good light you won't see
much, even through the most expensive magnifier. Ideally
you need bright daylight, bright ceiling lights or a table
light close to the object . If you are a trader buying at pre-dawn fairs or viewing in a dimly-lit
auction hall, or if you are partially-sighted you may require
very bright light. The light must be between the magnifier
and the object, do not shine the light at the magnifier,
you will merely be blinded by reflections.
The solution: a magnifier with a built
in light. These come in large sizes (reading
magnifier) or small sizes (jewellers
loupes.) You could, of course, simply use a torch, but
then you need one hand to hold the torch, one to hold the
magnifier and a third hand to hold the item. For hands-free
use there is the illuminated
binocular headband magnifier described above, or a mains-powered magnfier-light.
When using an illuminated magnifier do remember to hold
it with the light shining towards the object and not into
your eyes - I know this sounds obvious, but a significant
percentage of customers at the QUICKTEST stand get it wrong.
THE
RULES AND THE MATERIALS
Two rules. Firstly
large lenses made of glass are very heavy whereas plastic
is lightweight. Of course, plastic scratches easily, glass
doesn't. But don't think that a lens has to be made of glass
to be any good, the most expensive lenses (e.g. a Zeiss
jewellers loupe at £85.00) are made of plastic...though
'plastic' sounds too downmarket so I say, "High grade
optical acrylic".
Secondly, magnification,
size and working distance. The more powerful the lens the
smaller it will be and the closer you must hold it
to the object ('working distance'). Conversely, the less
powerful the lens the larger it will be and the further
you can hold it from the object. Read that again, memorise
it - it applies to all magnifiers everywhere. There is always
a compromise between high magnification (small lens) and
large lens (low magnification).
These are the rules.
They are not my rules. They are the rules of nature, there
is no way round them IF YOU WANT A SIMPLE HANDHELD MAGNIFIER.
If you want a powerful magnifier that is large and / or
has a long working distance, there are four types, as follows.
A head-worn magnifier
made out of two little telescopes as used by surgeons (I call
them Surgeons'
Magnifiers); a high quality low-power
microscope (I also have various models secondhand); a scanner
that connects to a computer or TV to enlarge print in a book
or newspaper (we will have these in October);
a microscope with a stereoscopic projection system, such as the Mantis.
You will notice that we sell two pocket
microscopes each with a magnification of 30X, and a large micrscope with magnifications (selectable) of 2X, 4X and 6X. And you might notice that the 30X microscopes sell for £4.00 and £6.00 and the 2X, 4X, 6X microscope sells for £1250.00. This is because it is always the quality of the optics you pay for, not the power of the lens. This applies not only to microscopes but to simple handheld readers.
QUALITY AND PRICE
When you look through a lens don't simply marvel at 'how
large' everything appears. Look to see if faint objects
show up against the background or are fuzzy; if straight
lines appear straight or curved; if the image is clear around
the edges of the lens or wobbly; if colours are true. Lighting is important too. If you are using an illuminated magnifier, is the light bright enough, and does it actually point at the object...even when the magnifier is tilted at different angles? These
are the differences between the cheapest and most expensive
lenses and you can see for yourself by trying them out at
the QUICKTEST stand at the antiques fairs. Or if you buy
by mail and the magnifier turns out to be unsuitable, you
can return it.
We are specialist optical dealers and very fussy about the quality of our triplet (and 4-element) loupes. I have samples of 'triplets' form a supplier specialising in triplet lenses and claiming that only they supply genuine high-quality 'triplet's - and I can see immediately that they are very poor optical quality and I have dismantled them and the lenses are not triplets! If you have bought one of them, buy one of ours too, compare the two, and return the one you don't want.
TECHNICAL
STUFF: MAGNIFICATION AND WORKING DISTANCE
Some magnifiers are
marked with the magnification, some are marked with the
focal length (working distance) in inches.
The focal length is
the ideal distance between the lens and the object, not
too close (or the lens won't magnify) and not too far (or
the image appears wobbly). And if you hold the lens MUCH
too far from the object, the image will appear upside down.
Most people don't understand
'focal length' and so when they see a '3' (for some reason
eyeglasses are often marked like this) they think it means
"3X magnification" when it really means "three
inch Focal length". Matters are made worse by
the fact that many manufacturers are 'approximate' in their
calculations, you can measure the working distance of a
1" magnifier and find it is nearer to 2".
So what is the relationship
between focal length (working distance) and magnification?.
Here is the way I calculate it.
If you take a 'normal'
working distance for reading to be 14" then a 7"
magnifier brings you twice as close = 2X magnification.
This '14 inch rule" is what I use in my catalogue to
calculate magnification:
4" = 3.5 magnification.
3.5 = 4X magnification.
3" = 4.5X magnification.
2.5 = 5.5X magnification.
2" = 7X magnification.
1.5" = 9X magnification
(but our eyeglasses are closer to 8X).
This system mystifies
opticians because focal length is a physical constant that
can be calculated, there isn't really such a thing as a
'normal' working distance, it varies from person to person. Opticians
use a different system, the dioptre. +4.00D is (for
a normal-sighted person) 2X magnification NOT, as you will
see in the 'gadget' mail order catalogues 4X magnification.
Furthermore, +4.00D is the strongest reading spectacle that
an be legally sold 'over-the-counter', if you need stronger
you must go to an optician (this rule doesn't apply to handheld
magnifiers, merely to the type of head-worn magnifier we
call "reading spectacles"). At the bottom of this
page is a more detailed explanation, scroll down or click
here.
MORE
TECHNICAL STUFF
If you wear spectacles,
should you keep them on whilst using a magnifier?
When using a large magnifier
(e.g. for reading) the answer is: yes. I assume,
here, that you need a magnifier because the print / map
/ mark is exceptionally small and you need that extra help
in addition to your spectacles.
When using a small magnifier
(e.g. a jeweller's loupe or watchmaker's eyeglass): do whichever
is the most comfortable, but you must keep the magnifier
as close to your eye as possible.
The only time you may
wish to think about whether to keep your spectacles on or
take them off is if you are wearing a magnifier over your
head (e.g. a binocular headband magnifier), they can be
used with or without spectacles, as follows:
If you are short-sighted (you have difficulty
in seeing far objects, your spectacle lens prescription
has a power beginning 'minus' ) you will notice that when
using the magnifier without your spectacles the working
distance is less than marked on the magnifier. If you are
very short-sighted you will also notice that without
a magnifier you can focus on very close objects -
you have magnifying eyes for close objects (the only drawback
being that you can't focus on far objects). The consequence
is that with a binocular magnifier you may choose between
two magnifications, one (weaker / further away) when you
wear the magnifier over your distance spectacles and one
(closer / stronger) when you wear the magnifier without
spectacles, whichever you find the most comfortable.
If you are long-sighted (you have difficulty
in seeing near objects, your spectacle lens prescription
has a power beginning "plus") you will notice
that when using the magnifier without your spectacles,
the working distance is more than stated on the magnifier.
If you are very long-sighted you will also notice
that a low-power magnifier doesn't actually magnify at all,
it merely brings close objects into focus at a 'normal'
viewing (eg reading) distance, which is exactly what your
reading spectacles do: they are low-power magnifiers. The
consequence is that with a binocular magnifier you may choose
between two magnifications, one (stronger / closer) when
you wear the magnifier over your spectacles and one (weaker
/ further away) when you wear the magnifier without spectacles,
whichever you find the most comfortable.
CONCLUSION
If you are buying by mail I hope the
above will help you make your choice, and as with any item
bought from us by mail unseen, you can return any item that
is unsuitable for exchange, credit or refund (your choice)
providing it is returned in its original condition within
fourteen days.
If you are visiting the QUICKTEST stand
at a fair, simply try them out. Bring with you something
familiar, e.g. a coin or stamp if you are a coin or stamp
dealer, a book, photograph, print etc. If you have an existing
magnifier and wish to upgrade, bring it with you so that
you can compare - we will not be offended, if your existing
magnifier is better than anything we have, we will be eager
to see it!
We help thousands of people choose magnifiers,
we really do understand magnifiers. However, we are not
opticians, we cannot comment on your spectacle prescription;
we are not doctors, we cannot comment on your eye condition,
you must consult an optician or doctor if you have
concerns about your eyes.
FOCAL LENGTH, DIOPTRES
AND MAGNIFICATION
The focal length is the distance you hold the lens from
the object that gives the most magnification and the clearest
image; it is also the point at which a distant bright object
(e.g. the sun) makes the smallest image (e.g. to make a
fire using the sun); it is also the distance at which you
can project a bright scene onto a surface, e.g. stand in
a dimly-lit hallway and project the image of a bright window
onto the wall. Try it with any magnifier, the distance from
the lens to the object will be the same with each of the
above experiments, this is the focal length of the lens.
In practical terms we can also describe this as, "the
[ideal] working distance."
'Dioptre' is the reciprocal of the focal length. To write
this as a formula, we call the power (magnification) P
and the focal length f, which gives us: P = 1 / f.
Those who are good at algebra can now work out the formula
to convert dioptre to power (magnification): P = D / 4 +
1. So, for instance, a typical lens you clip to the front
of spectacles will be marked +4.00D giving a a power (magnification)
of 4 / 4 + 1 = 2X (NOT "4X magnification" as most
mail order catalogues state). Zeiss loupes are marked in
dioptre too, their +36D lens is 36 / 4 + 1 = 10X.
RECOMMENDATIONS
For reading books, papers, magazines, directories, recipes,
and maps in daylight see any of our readers.
For large-area magnifiers try the flat Fresnel lenses, some are small (the size of a credit card) and some
are large (page-size). We have, of course, many traditional
magnifiers
with handles. If you don't like the idea of holding a
magnifier for hours, try a magnifier on
a stand. One I particularly like is a large reading magnifier 2X 80X80 on a handle, and the handle can be tilted to rest on the page, AND it has four powerful L.E.D. lights so that the print is always brightly lit no matter how you tilt the lens. For the strongest hands-free magnifiers (though
these are more intended for jewellers and engineers) there
are various
head-worn magnifiers. A compromise between 'handheld'
and 'hands-free' are the magnifiers you rest on the page (you
slide them along the page), the bar
magnifier is low magnification but excellent for dyslexics
(it stops the eye wondering) or, on the same page, the dome
magnifier is a good choice for the partially-sighted.
For the partially-sighted I would also recommend the 2X 80X80 listed above or (for the very-nearly blind) the folding
hand magnifier with two LED lights.
For mapreading in the car (including at night time)
any of the illuminated readers will do, my favourite is the 2X 80X80. I also keep,
in the car the largest
hand magnifier - it is large enough to cover most of a
page, enabling me to keep glancing up at the road signs and
then back at the magnifier and not lose my place on the map..but
it doesn't have a light. There are also four sizes of illuminated
Lumagny
magnifiers, to my expert eyes these are not very good quality,
but they do start at just £2.50 and are about half the
price as the car accessory shops.
For carrying in the pocket for occasional reading,
e.g. the labels on supermarket products, the 'small print'
on forms, those horrible photo-reduced instruction sheets.
The credit-card size Fresnel
(flat) magnifier is good, though not particularly high in
magnification. For a good selection pocket-size magnifiers
see our small
folding magnifiers. I would also recommend the larger
of the illuminated
magnifiers (the smaller, more powerful, versions are for
jewellers and diamond dealers).
For sewing, embroidery and other flat-ish craft work
any of the hands-free
magnifiers are good, if you need extra magnification you
could even try a
head-worn magnifier though you might think that these
are a bit 'over the top'. There are two good magnifiers on stands, one with a light and one without a light.
For model-making, watch and clock repairing and other
engineering jobs including lathe work, also fly-tying the
head-worn magnifiers are ideal. For particularly close
work you should consider a magnifier that clips
to spectacles or (on the same page) a watchmakers
eyeglass. The larger magnifiers listed above, under sewing,
embroidery etc would also be suitable. My colleage has the one on a stand set up by the lathe in the workshop. The ultimate workshop magnifier is the large Mantis stereo microscope.
For stamps & coins, prints & postcards, fabrics
etc the powerful stand
magnifiers are good (traditionally, the 'Linen provers'
are for measuring the threads-per-inch), or you could even
use a pocket
microscope - these are all for use on flat objects.
Alternatively, any loupe
(with or without a light) or eyeglass.
For prolonged use on in a laboratory or workshop the ulitimate magnifier is the Mantis...or you might
like to see a selection of secondhand
microscopes.
For jewellery, gemstones and very small marks on antiques,
also insects and plant samples choose any loupe
(with or without a light) or eyeglass.
Traditionally 10X magnification is used by gem and diamond
dealers, a magnifier will be your most important tool, buy
the best you can afford. For larger marks (e.g. on porcelain
and furniture) any folding
magnifier should suffice.
Decorative magnifiers / gifts, I don't really sell
magnifiers 'just for decoration', but you could try the
pendant magnifier (regular line), or see if I have any
end-of-lines.
Spare parts, I have many bulbs,
pouches, chains etc for magnifiers.
Site
map - to see all categories of magnifier
XXXXXXX
Large print
SIZE
AND MAGNIFICATION
The size of a magnifier is given as two
figures, e.g. 10X18. The first figure is the magnification,
the second figure is the diameter of the lens in millimeters.
So 10X18 means that the magnification is 10X
(makes items appear ten times larger than normal) and the
lens size is 18mm diameter.
Sometime the lens is square. You will still see the magnification followed by the lens size, as above, but it will look something like this: 2X 80X80 (that would mean 2X magnification with a lens size of 80mm X 80mm.
Incidentally, exactly the same applies
to binoculars and telescopes, the 'diameter' being that
of the big lens (the objective lens) so a "7X50"
binocular or telescope has a magnification of 7X and objective
lens diameter(s) of 50mm.
Having grasped these basics, customers tend to ask: "What
is the most powerful (highest magnification) I can buy?"
And then, "What is the LARGEST lens with the highest
magnification?"
These are the wrong questions.
The questions should be, "What
magnification do I need?" and "How does the quality
(how clearly I will see) vary? - and is a powerful magnifier
as 'clear' as a less powerful magnified? - and are there
different types of magnifier?
MAGNIFIERS - THE
NAMES
Don't be embarrassed if you get the names
wrong, nearly everyone confuses a loupe with an eyeglass,
most people refer to 'the flat magnifier' when they mean Fresnel,
or 'the thing you stick round your head' when they mean 'headband
magnifier'. Here are the true names.
Any magnifier large enough to read text
(e.g. newspapers, tins in a supermarket) is a 'reading
magnifier'. Some are large with plastic handles (I call them Readers), some
fold or slide into cases (I call them General Purpose Magnifiers), some are small
(30mm across), some are large (a few inches). One interesting
variation is the 'Fresnel' (pronounced Fren-nel because it's French), a flat sheet of magnifying plastic,
the size can be credit card size up to page-size. Whatever the technical name, these are
all 'reading magnifiers'.
A jeweller's loupe (pronounced 'loop')
is a small folding magnifier (from 12mm to 21mm diameter)
of high magnification (usually 10X or 20X) which folds into
a metal or plastic case. A watchmaker's eyeglass is a cone
of plastic, you hold the open end in your eye (it takes
practice!). The IDEA of a watchmaker's eyeglass is that
there's enough working distance to repair the watch, which
means that the magnification must be low (more about this
later).
As a guide to quality, both loupes and
eyeglasses start at at £2.00 but the best eyeglasses cost
£4.50 whereas a good quality loupe costs £20.00 and the
best quality £85.00 (quality is paramount when viewing gemstones
and diamonds or detecting the more 'difficult' forgeries
in stamps and coins).
Finally, hands-free magnifiers: there's
a the page-size lens that hangs
around the neck (good for reading, sewing, embroidery,
fly-tying, good value at £5.00); watchmakers eyeglasses you
hold in your eye (see above); various lenses that clip to
spectacles; binocular
headband magnifiers (includes a selection of clip-on
lenses and an adjustable light, £20.00).
Apart from deciding on the APPROXIMATE
magnification (2X or 10X) and APPROXIMATE size (pocket-size
or page-size) and APPROXIMATE quality (£2.00 or £20.00)
there is no rule about which type of magnifier to use. Some
professional engineers buy a the cheapest largest reading
magnifier because they don't like to spend money, some hobbyists
will spend £85.00 on a Zeiss 10X20 loupe simply because
they want the best and they can afford it.
HOW TO USE A MAGNIFIER
With a large magnifier (e.g. for reading
books, small print etc) hold the magnifier part way between
your eye and the object. Now move the magnifier very slowly
backwards and forwards until you have the best image, not
too small, not too fuzzy. The idea with a large reading
magnifier is to set up straight, sit comfortably, you should
not have to bend over the magnifier and peer closely (though
it depends on the quality of the lens).
With a strong magnifier (e.g. a jewellers
loupe) hold the magnifier as close to your eye as possible
(if you wear spectacles you may leave them on or take them
off, whichever is the most comfortable). Next, bring the
object very close to the magnifier, so close that it's almost
touching. Finally, very slowly move the object away until
it is in focus.
LIGHTING
Lighting is as important as magnification,
as important as quality, without good light you won't see
much, even through the most expensive magnifier. Ideally
you need bright daylight, bright ceiling lights or a table
light close to the object . If you are a trader buying at pre-dawn fairs or viewing in a dimly-lit
auction hall, or if you are partially-sighted you may require
very bright light. The light must be between the magnifier
and the object, do not shine the light at the magnifier,
you will merely be blinded by reflections.
The solution: a magnifier with a built
in light. These come in large sizes (reading
magnifier) or small sizes (jewellers
loupes.) You could, of course, simply use a torch, but
then you need one hand to hold the torch, one to hold the
magnifier and a third hand to hold the item. For hands-free
use there is the illuminated
binocular headband magnifier described above, or a mains-powered magnfier-light.
When using an illuminated magnifier do remember to hold
it with the light shining towards the object and not into
your eyes - I know this sounds obvious, but a significant
percentage of customers at the QUICKTEST stand get it wrong.
THE
RULES AND THE MATERIALS
Two rules. Firstly large lenses made of glass are very heavy whereas plastic
is lightweight. Of course, plastic scratches easily, glass
doesn't. But don't think that a lens has to be made of glass
to be any good, the most expensive lenses (e.g. a Zeiss
jewellers loupe at £85.00) are made of plastic...though
'plastic' sounds too downmarket so I say, "High grade
optical acrylic".
Secondly, magnification,
size and working distance. The more powerful the lens the
smaller it will be and the closer you must hold it
to the object ('working distance'). Conversely, the less
powerful the lens the larger it will be and the further
you can hold it from the object. Read that again, memorise
it - it applies to all magnifiers everywhere. There is always
a compromise between high magnification (small lens) and
large lens (low magnification).
These are the rules.
They are not my rules. They are the rules of nature, there
is no way round them IF YOU WANT A SIMPLE HANDHELD MAGNIFIER.
If you want a powerful magnifier that is large and / or
has a long working distance, there are four types, as follows.
A head-worn magnifier
made out of two little telescopes as used by surgeons (I call
them Surgeons'
Magnifiers); a high quality low-power
microscope (I also have various models secondhand); a scanner
that connects to a computer or TV to enlarge print in a book
or newspaper (we will have these in October); a microscope with a stereoscopic projection system, such as the Mantis.
You will notice that we sell two pocket
microscopes each with a magnification of 30X, and a large micrscope with magnifications (selectable) of 2X, 4X and 6X. And you might notice that the 30X microscopes sell for £4.00 and £6.00 and the 2X, 4X, 6X microscope sells for £1250.00. This is because it is always the quality of the optics you pay for, not the power of the lens. This applies not only to microscopes but to simple handheld readers.
QUALITY AND PRICE
When you look through a lens don't simply marvel at 'how
large' everything appears. Look to see if faint objects
show up against the background or are fuzzy; if straight
lines appear straight or curved; if the image is clear around
the edges of the lens or wobbly; if colours are true. Lighting is important too. If you are using an illuminated magnifier, is the light bright enough, and does it actually point at the object...even when the magnifier is tilted at different angles? These
are the differences between the cheapest and most expensive
lenses and you can see for yourself by trying them out at
the QUICKTEST stand at the antiques fairs. Or if you buy
by mail and the magnifier turns out to be unsuitable, you
can return it.
We are specialist optical dealers and very fussy about the quality of our triplet (and 4-element) loupes. I have samples of 'triplets' form a supplier specialising in triplet lenses and claiming that only they supply genuine high-quality 'triplet's - and I can see immediately that they are very poor optical quality and I have dismantled them and the lenses are not triplets! If you have bought one of them, buy one of ours too, compare the two, and return the one you don't want.
TECHNICAL
STUFF: MAGNIFICATION AND WORKING DISTANCE
Some magnifiers are
marked with the magnification, some are marked with the
focal length (working distance) in inches.
The focal length is
the ideal distance between the lens and the object, not
too close (or the lens won't magnify) and not too far (or
the image appears wobbly). And if you hold the lens MUCH
too far from the object, the image will appear upside down.
Most people don't understand
'focal length' and so when they see a '3' (for some reason
eyeglasses are often marked like this) they think it means
"3X magnification" when it really means "three
inch Focal length". Matters are made worse by
the fact that many manufacturers are 'approximate' in their
calculations, you can measure the working distance of a
1" magnifier and find it is nearer to 2".
So what is the relationship
between focal length (working distance) and magnification?.
Here is the way I calculate it.
If you take a 'normal'
working distance for reading to be 14" then a 7"
magnifier brings you twice as close = 2X magnification.
This '14 inch rule" is what I use in my catalogue to
calculate magnification:
4" = 3.5 magnification.
3.5 = 4X magnification.
3" = 4.5X magnification.
2.5 = 5.5X magnification.
2" = 7X magnification.
1.5" = 9X magnification
(but our eyeglasses are closer to 8X).
This system mystifies
opticians because focal length is a physical constant that
can be calculated, there isn't really such a thing as a
'normal' working distance, it varies from person to person. Opticians
use a different system, the dioptre. +4.00D is (for
a normal-sighted person) 2X magnification NOT, as you will
see in the 'gadget' mail order catalogues 4X magnification.
Furthermore, +4.00D is the strongest reading spectacle that
an be legally sold 'over-the-counter', if you need stronger
you must go to an optician (this rule doesn't apply to handheld
magnifiers, merely to the type of head-worn magnifier we
call "reading spectacles"). At the bottom of this
page is a more detailed explanation, scroll down or click here.
MORE
TECHNICAL STUFF
If you wear spectacles,
should you keep them on whilst using a magnifier?
When using a large magnifier
(e.g. for reading) the answer is: yes. I assume,
here, that you need a magnifier because the print / map
/ mark is exceptionally small and you need that extra help
in addition to your spectacles.
When using a small magnifier
(e.g. a jeweller's loupe or watchmaker's eyeglass): do whichever
is the most comfortable, but you must keep the magnifier
as close to your eye as possible.
The only time you may
wish to think about whether to keep your spectacles on or
take them off is if you are wearing a magnifier over your
head (e.g. a binocular headband magnifier), they can be
used with or without spectacles, as follows:
If you are short-sighted (you have difficulty
in seeing far objects, your spectacle lens prescription
has a power beginning 'minus' ) you will notice that when
using the magnifier without your spectacles the working
distance is less than marked on the magnifier. If you are very short-sighted you will also notice that without
a magnifier you can focus on very close objects -
you have magnifying eyes for close objects (the only drawback
being that you can't focus on far objects). The consequence
is that with a binocular magnifier you may choose between
two magnifications, one (weaker / further away) when you
wear the magnifier over your distance spectacles and one
(closer / stronger) when you wear the magnifier without
spectacles, whichever you find the most comfortable.
If you are long-sighted (you have difficulty
in seeing near objects, your spectacle lens prescription
has a power beginning "plus") you will notice
that when using the magnifier without your spectacles,
the working distance is more than stated on the magnifier.
If you are very long-sighted you will also notice
that a low-power magnifier doesn't actually magnify at all,
it merely brings close objects into focus at a 'normal'
viewing (eg reading) distance, which is exactly what your
reading spectacles do: they are low-power magnifiers. The
consequence is that with a binocular magnifier you may choose
between two magnifications, one (stronger / closer) when
you wear the magnifier over your spectacles and one (weaker
/ further away) when you wear the magnifier without spectacles,
whichever you find the most comfortable.
CONCLUSION
If you are buying by mail I hope the
above will help you make your choice, and as with any item
bought from us by mail unseen, you can return any item that
is unsuitable for exchange, credit or refund (your choice)
providing it is returned in its original condition within
fourteen days.
If you are visiting the QUICKTEST stand
at a fair, simply try them out. Bring with you something
familiar, e.g. a coin or stamp if you are a coin or stamp
dealer, a book, photograph, print etc. If you have an existing
magnifier and wish to upgrade, bring it with you so that
you can compare - we will not be offended, if your existing
magnifier is better than anything we have, we will be eager
to see it!
We help thousands of people choose magnifiers,
we really do understand magnifiers. However, we are not
opticians, we cannot comment on your spectacle prescription;
we are not doctors, we cannot comment on your eye condition,
you must consult an optician or doctor if you have
concerns about your eyes.
FOCAL LENGTH, DIOPTRES
AND MAGNIFICATION
The focal length is the distance you hold the lens from
the object that gives the most magnification and the clearest
image; it is also the point at which a distant bright object
(e.g. the sun) makes the smallest image (e.g. to make a
fire using the sun); it is also the distance at which you
can project a bright scene onto a surface, e.g. stand in
a dimly-lit hallway and project the image of a bright window
onto the wall. Try it with any magnifier, the distance from
the lens to the object will be the same with each of the
above experiments, this is the focal length of the lens.
In practical terms we can also describe this as, "the
[ideal] working distance."
'Dioptre' is the reciprocal of the focal length. To write
this as a formula, we call the power (magnification) P and the focal length f, which gives us: P = 1 / f.
Those who are good at algebra can now work out the formula
to convert dioptre to power (magnification): P = D / 4 +
1. So, for instance, a typical lens you clip to the front
of spectacles will be marked +4.00D giving a a power (magnification)
of 4 / 4 + 1 = 2X (NOT "4X magnification" as most
mail order catalogues state). Zeiss loupes are marked in
dioptre too, their +36D lens is 36 / 4 + 1 = 10X.
RECOMMENDATIONS
For reading books, papers, magazines, directories, recipes,
and maps in daylight see any of our readers.
For large-area magnifiers try the flat Fresnel lenses, some are small (the size of a credit card) and some
are large (page-size). We have, of course, many traditional magnifiers
with handles. If you don't like the idea of holding a
magnifier for hours, try a magnifier on
a stand. One I particularly like is a large reading magnifier 2X 80X80 on a handle, and the handle can be tilted to rest on the page, AND it has four powerful L.E.D. lights so that the print is always brightly lit no matter how you tilt the lens. For the strongest hands-free magnifiers (though
these are more intended for jewellers and engineers) there
are various head-worn magnifiers. A compromise between 'handheld'
and 'hands-free' are the magnifiers you rest on the page (you
slide them along the page), the bar
magnifier is low magnification but excellent for dyslexics
(it stops the eye wondering) or, on the same page, the dome
magnifier is a good choice for the partially-sighted.
For the partially-sighted I would also recommend the 2X 80X80 listed above or (for the very-nearly blind) the folding
hand magnifier with two LED lights.
For mapreading in the car (including at night time)
any of the illuminated readers will do, my favourite is the 2X 80X80. I also keep,
in the car the largest
hand magnifier - it is large enough to cover most of a
page, enabling me to keep glancing up at the road signs and
then back at the magnifier and not lose my place on the map..but
it doesn't have a light. There are also four sizes of illuminated Lumagny magnifiers, to my expert eyes these are not very good quality,
but they do start at just £2.50 and are about half the
price as the car accessory shops.
For carrying in the pocket for occasional reading,
e.g. the labels on supermarket products, the 'small print'
on forms, those horrible photo-reduced instruction sheets.
The credit-card size Fresnel
(flat) magnifier is good, though not particularly high in
magnification. For a good selection pocket-size magnifiers
see our small
folding magnifiers. I would also recommend the larger
of the illuminated
magnifiers (the smaller, more powerful, versions are for
jewellers and diamond dealers).
For sewing, embroidery and other flat-ish craft work any of the hands-free
magnifiers are good, if you need extra magnification you
could even try a head-worn magnifier though you might think that these
are a bit 'over the top'. There are two good magnifiers on stands, one with a light and one without a light.
For model-making, watch and clock repairing and other
engineering jobs including lathe work, also fly-tying the head-worn magnifiers are ideal. For particularly close
work you should consider a magnifier that clips
to spectacles or (on the same page) a watchmakers
eyeglass. The larger magnifiers listed above, under sewing,
embroidery etc would also be suitable. My colleage has the one on a stand set up by the lathe in the workshop. The ultimate workshop magnifier is the large Mantis stereo microscope.
For stamps & coins, prints & postcards, fabrics
etc the powerful stand
magnifiers are good (traditionally, the 'Linen provers'
are for measuring the threads-per-inch), or you could even
use a pocket
microscope - these are all for use on flat objects.
Alternatively, any loupe (with or without a light) or eyeglass.
For prolonged use on in a laboratory or workshop the ulitimate magnifier is the Mantis...or you might
like to see a selection of secondhand
microscopes.
For jewellery, gemstones and very small marks on antiques,
also insects and plant samples choose any loupe (with or without a light) or eyeglass.
Traditionally 10X magnification is used by gem and diamond
dealers, a magnifier will be your most important tool, buy
the best you can afford. For larger marks (e.g. on porcelain
and furniture) any folding
magnifier should suffice.
Decorative magnifiers / gifts, I don't really sell
magnifiers 'just for decoration', but you could try the pendant magnifier (regular line), or see if I have any end-of-lines.
Spare parts, I have many bulbs,
pouches, chains etc for magnifiers.
Site
map - to see all categories of magnifier
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