A typical example.

Getting started with a low power microscope

Tips on how to use the 20x monocular microscope frequently recommended as a first microscope for youngsters.

by David Walker, UK

 

Why is it recommended?
It's not a toy; has coated achromatic glass objective and sturdy metal mechanics.

Mag of 20x extends what the naked eye can see but user can still relate what they see to the subject.

No sample preparation; objects around the house, insects, plants from the garden, larger pond critters readily studied. The large simple controls are particularly suited to the very young rather than a more fiddly compound microscope.

Monocular better for very young as may have difficulty with a stereo. Angled eyepiece tube more comfortable than vertical tube often seen on cheaper stereos.

No image inversion (unlike a compound microscope); easier to gain experience with subject manipulation.

Still useful for low power studies if buy a higher power student compound microscope.

Where can I buy one for me or as a gift?
Look for 'low power', 'monocular', 'dissecting microscope' in catalogues or on the websites of microscope dealers, larger photo outlets and optics shops.

How much do they cost?*
UK: typically 46 - 58, e.g. at Brunel Microscopes, Optical Vision, Amazon.

USA: typically $80 - $100, e.g. at Edmund Scientific, Mel Sobel Microscope Store.

This microscope may seem expensive compared with a toy microscope in high street shops, but most models in toy shops especially those claiming high mags will discourage a youngster not encourage them! Click here for an extended explanation.

*The dealers suggested are examples, the author has no affiliation with any suppliers.

  

This page isn't intended to be read linearly;  just dip in to any tip of interest! 
The tips are written from the perspective of an adult supervising a youngster
or older beginner using this type of microscope.

Getting started.
A few tips for the beginner to the scope and what accessories are useful.

  

Top lighting.
LED torches are ideal and batteries have long life.

 

 

Bottom lighting.
Use white disc supplied or sit scope on a 35mm slide viewing box.

How to measure things.
Put 1 mm graph paper or rule in field of view.

 

How to take photos.
Try a mobile phone, compact digicam, webcam - either handheld or on table tripod.

 

What to look at.
Image gallery of photos.

Around the home: Plants / 'bugs': Pond life: Prepared slides: what subjects are suitable.
Includes tips for studying different types of subject.

When a compound microscope
is needed
.

 

 

Comments to the author David Walker are welcomed.
All images by the author.
Thank you to my brother Ian for the loan of the Sony P200 digicam.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Getting started: A few tips. (Note: the total magnification of 20x is given by the magnification of the objective (2x) multiplied by that of the eyepiece, usually 10x.)

A: Eyepiece. A 10x eyepiece is usually supplied with the 2x objective. A captive screw enables eyepiece to be removed. Some dealers do offer 20x eyepieces to increase total mag to 40x, but the optics do not justify this if the author's example is typical; the images are larger but reveal little extra detail. A better option is to reduce the eyepiece to say 5x-7x to allow larger field views of eg pond life. Most standard compound microscope eyepieces will suffice.
B: Focus knob. For larger objects you may need to release knob C and raise unit on stand to focus.
D: Screw allows tube to be rotated or scope to be removed for cleaning.
E: A disc in the base, black one side and white the other, is usually supplied. See lighting section and image gallery for tips on using this.
F: Stage clips. For many subjects it's worth swinging the clips out of the way to allow larger subjects or trays of pond life to be studied. For studying e.g. paper and textiles, using the clips just outside field of view can hold subject flat.
G: Microscope height. Comfort in use is essential. The scope sits low on a typical table at a height that may be fine for many youngsters. For older users, try to get the eyepiece height at eye level without hunching. A computer monitor stand is ideal for this and gives a large waterproof working area.
Useful accessories. Shallow dishes like the tops of food containers, a small artist's paint brush, scissors and different coloured card are useful for preparing, manipulating and showing subjects.  Most smaller subjects can be put on the scope without preparation. See image gallery for tips on keeping some live critters still. If buying from a dealer they may offer a starter pack of tweezers, blank slides etc. For pond life the glass slides with a central depression are useful.

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Top lighting: Using the scope near a sunny window will be fine for many subjects. But a bright lamp would be better and essential at night! Only the small field of view (ca. 10 mm) needs illuminating so a desk lamp is overkill and can cause glare; a better choice is to try a battery powered LED torch as they give a good white light and are safe around youngsters. The batteries last a long time.

A homemade support can be made, or one of those cheap 'third hand' clamps from hobby shops is useful, or, as here, a stand for a magnifying glass. The torch is the popular MagLite design converted to LED as they last a lot longer on batteries than bulb supplied.

When studying a subject, experiment with the angle, height and direction of the lighting as different subjects often need different lighting to reveal extra detail and give modelling of the subject for photos.

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Bottom lighting: Most microscope models of this design have a reversible black and white disc in the base. Just try both sides for different subjects and see which is preferred. Subjects that are transparent to some degree can work best with a white base as some light is reflected back from the disc through the subject.

Another method for transparent subjects and in the author's view better, is to sit the scope on a light box for 35mm photographic slides; the model with viewing size ca. 5x4 inches is ideal. They provide an even white light that is excellent for this purpose. The model shown is sold by Jessops (UK) (model JESLB45) for 15* but most photo shops should sell them. They can run on batteries so enables use outdoors but indoors it's worth buying the low voltage power supply. *Update Dec. 2015. This style of light panel using a fluorescent lamp is now dated. The modern equivalents are the slimmer LED 5x4 inch panels and are better suited. See this Micscape article 'The versatile light panel'.

With a light box the opaque base disc is removed and can be replaced by a thick cardboard disc with ca 12 mm hole in to allow light through and to give support to e.g. glass slides (as shown right). Or even better a clear plastic disc made of e.g. Perspex.

The low voltage supply* makes it ideal for kids and if pond water is being splashed about. The base can also work well as a first light source for a compound microscope which doesn't have a mirror, e.g. with the popular Russian LOMO Biolam stands.
*Note that there are higher voltages generated inside the box for the older fluorescent tube type panels so shouldn't be dismantled by youngsters and avoid liberal splashes of water on it. The modern LED designs are safer.

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How to take photos: Many of the digicams, webcams or mobile phones with compact lenses can often give a competent image by carefully holding the camera to the eyepiece with good lighting. Part of the fun of photography through a microscope is 'try it and see'. Try the different camera modes and experiment with various supports.

Quick photo method:
Carefully focus microscope and compose subject. Experiment with lighting for good modelling and try to get the lighting as even as possible.
Try the camera on Autofocus and see if camera focuses on projected image. If not retry with the Macro setting if available. The Sony P200 autfocus worked well in Macro mode. If the camera has a fixed focus e.g. on a mobile phone, you may need to refocus microscope as well as possible using the preview screen if available on camera.
More experienced users with full featured cameras may wish to do a white balance on the light used and experiment with auto focus, fixed focus, ISO, shutter and aperture if adjustable to find a set of conditions that works best i.e. to give sharp, well lit, contrasty images!

Experiment with the optical zoom if present (not the digital zoom). Depending on subject, the full field of view with black circle or zoomed in can be tried (see image gallery). Note that for handheld work keeping the zoom at its minimum will minimise camera shake.

A simple handheld setup is shown right (seen without a light source for clarity). A Sony P200 7 Megapixel digicam with 3x optical zoom is shown. For models like this Sony with extending lenses, care needs to be taken, but the lens mount can be held lightly to align with the eyepiece which is almost the same width.

With the lighting chosen keep an eye on what the camera shutter speed is being set if displayed. Handheld with care down to about 1/20th second is doable. If it has a manual mode it's best to choose the widest aperture to achieve the highest shutter speed.

Note that for cameras with 'larger bore' lens designs this method will probably not work, i.e. only a tiny light spot may be seen even if optical zoom set at max and will be hard to align a wide lens with slim eyepiece.

A sturdier set-up to avoid camera shake is shown left with bottom lighting. A slim tripod can be put to good use (a Velbon with telescopic legs is shown). The microscope needs to be focussed first and then the height and angle of tripod set so as the camera lens aligns well with eyepiece. Keeping a few mm or so gap between lens and eyepiece is advisable with cameras where the auto shut off extends the lens further before closing (the Sony P200 lens does).

If a tripod can be dedicated to the scope (they're very cheap), the height and head angle can be set permanently allowing rapid use of a camera when needed.

 

Try different lighting: The topaz crystal shown right demonstrates the value of trying different lighting. The upper one is seen with top lighting only with black disc below. It shows its true colour well and external growths.

The same crystal lower right was photographed using bottom lighting only from a light box. It doesn't show its true colour well but shows better the internal features, whereas opaque external growths are black.

Remember, there's no 'correct' lighting, try variations of lighting or in combination to see what is revealed for different types of subject.

Lower mag eyepiece: Also used for the crystal was an old Baker 5x eyepiece instead of the supplied 10x, i.e. total mag was now 10x. The crystal was too large for 20x mag and has shallow depth of field. Reducing the mag showed all the crystal and gave more depth.


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How to measure things: Appreciating the size of a subject is a key concept when using a microscope. At 20x a strip of graph paper with 1 mm divisions placed in the field of view or a transparent rule can give an estimate of size both visually and when taking photos, as shown right. Here the eyes of both a normal and quick thread needle are compared.

One advantage of a fixed 20x mag is that the field of view once measured is constant, typically 9 mm diameter. So a photo showing the full field can be used without a measuring strip to judge subject size.

This photo also shows the benefit of using both top and bottom lighting at the same time to give surface detail to opaque subjects.

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When a compound microscope is needed. The 20x scope is fine for showing gross features of the type of subjects shown in the image gallery but struggles with fine detail in larger subjects and when the subject is just a few mm in size or smaller. Although the optics are competent for the price they aren't as crisp as those in more expensive low power microscopes. This is why using a higher mag eyepiece e.g. 20x to give a total mag of 40x on this sort of scope doesn't reveal much more. A cheap student compound microscope with optical mag of 40x will reveal more detail.

If from the outset the youngster or beginner of any age is interested in cellular detail of plant and animal specimens, or smaller pond critters, a student compound microscope would be better. A compound microscope does require some sample preparation and a wide range of prepared slides are available to get started. (See this article for an extended explanation of a compound microscope use.)

Here's a comparison between the 20x microscope and a student compound microscope at approx. lowest power of 35x. (Camera on a tripod to avoid camera shake).

 
20x microscope: Pumpkin stem T/S section, prepared slide (Biosil). The mag is too low and optics not crisp enough to resolve smaller detail although larger structures are clearly seen. Putting a 15x-20x eyepiece on to achieve 35x-40x wouldn't really improve matters. (It's commonly known as 'empty magnification'.)

 
Student LOMO compound microscope, 35x optical: ca. full eyepiece view with 3.5x objective. Although a modest increase in mag cf the 20x scope, at 35x on a compound microscope the smaller detail is much crisper. With the 10x objective to give ca. 100x optical mag, smaller features will be very clear.

 

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 Image gallery: These were all taken with the 20x microscope described, using a handheld Sony P200 digicam,
Autofocus, shutter 1/20th - 1/50th sec.  Images with black border - the optical zoom was minimum, others had variable zoom settings and some cropping.

Around the home and garden - a good place to start!


Stamp detail. Printed papers are good flat subjects to start with. Newspapers, mags, stamps, photos, all have interesting aspects. Projects to explain how their microscopic differences relate to their use can be devised e.g. why does toilet paper structure differ to kitchen tissue or tea bag. Compare text from newspaper, inkjet printer and laser printer.


Patterned linen handkerchief showing the warp and weft. The many different textiles around the house can offer a wealth of subjects to show how patterns are built up, the different weaves etc. The slide clips positioned just outside field of view can hold part of a larger item of clothing flat to study.


Record stylus. Many manmade objects around the home are fascinating subjects. With care a record can be studied.

The appeal of microscopes is that the ordinary can offer plenty of interest when magnified.

 

Plants, 'bugs', pond life


An indoor fern leaf underside showing spore capsule and released spores. Parts of plants, leaves, flowers, thin layers cut across a stem (with adult supervision of a youngster) can be very rewarding.


Live freshwater shrimp from a garden pond, Gammarus. A 20x scope is useful for larger pond animals like these to study their gross features and how they behave. These can be very active and one way of slowing pond life is to limit their water to a small area and then remove the excess. They will be fine for sometime before returning to the pond. Small paint brushes and eyedroppers are useful for handling pond life.

You can spend a lifetime studying what nature reveals on the microscopic scale and why for many it does become a lifetime's hobby.
Freshwater ponds have a microcosm of life. Pond dipping  studies should of course be supervised for the young and appropriate hygiene precautions taken. See the 'Micscape Library' for a large range of pond life resources.


Live green hydra. A compound microscope is required for studying fine detail of larger animals and to study smaller critters such as water fleas, cyclops and even smaller critters like rotifers and protozoa.

 

Prepared slides

Prepared slides are primarily intended for study with a compound microscope typically at mags of 40x + , but many subjects can be studied at 20x to appreciate overall structure and can complement compound microscope studies. The types of slides that can work well is whole insects and larger insect parts, some animal parts like feathers. Many plant sections seen at 20x can show the general structure and larger cells but they really need higher mags to study in detail. Histology subjects such as animal organs and tissues arguably aren't best suited for the beginner; 20x is too low a mag for many histology subjects and a compound microscope is needed to reveal animal cell detail and requires more guidance on interpreting what is seen.


Insect wing. 20x can show the vein network, larger features like spines. Higher mags are needed to study smaller features like fine hairs etc. This a prepared slide but the windowsill, garage and other areas often supplies a wealth of dead insect to study.


Pheasant feather detail (Biosil slide). These and other larger animal parts are fascinating at 20x, and allows the detail that can be seen at higher mags to be appreciated.


Monarch butterfly wing detail. A prepared slide in this case (Biosil) but dead insects around the house and garden can be fun to study.


The 20x scope readily shows wing scale, a digicam with optical zoom can capture a good image. Each scales usually have much finer detail which a compound microscope will be needed to show.


Honey bee, third leg. The legs of a honeybee are fascinating as the bee has different 'tools' on its leg to help it in its 'work'.


Hedgehog flea. Prepared slide (Biosil).

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