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Microscope essentialsWhich microscope should I choose?
It really depends on your applications and we recommend you answer the question on the selection wizard at the top of our Microscope page to see a more manageable selection of microscopes related to your requirements. As a gift for a child, you will find that the high power microscope is more useful and has more educational value than the low power counterpart. There are many more activities that one can do with a high power microscope and high power observations are arguably more exciting. We have seen children spend literally hours examining pond water oganisms and insect parts with a microscope. Also, high power microscopes are generally the types used in schools.
THE RIGHT MICROSCOPE
Microscopes are configured to suit different applications. It is important to ensure that you purchase a microscope that is well-suited to your application. There are a few basic things you need to know:
Perhaps most important of all, do not fall into the trap of being attracted by high levels of magnification. The vast majority of the world�s light microscope applications require magnification levels of less than 200x!
Secondly, you need to know whether you need a compound or low-power/stereo microscope.
Compound or low-power microscope
Microscopes fall into two basic categories: Compound or Stereo, often referred to as high power and low power, respectively.
High power - also known as - Compound Microscope
A high power or compound microscope will be required if you wish to view small specimens such as blood samples, bacteria, pond scum, water organisms etc. Obviously, very small specimens require high magnification in order to see minute detail. Typically a high-power compound microscope has 1 to 3 objective lenses that range from 4x-100x and will deliver magnifications up to 500x or more.
Monocular microscopes with just one viewing eyepiece work well for up to 1000X magnification. For higher magnification levels, a binocular microscope is recommended. The total magnification achievable by a microscope is derived by multiplying the power of the eyepiece with that of the objective (the optical part nearest to the specimen). So in the case of a 10x eyepiece and 100x objective lens, the total magnification would be 1000 times.
Low-power and Stereo Microscopes
If you wish to view solid objects such as minerals, gems, rocks, coins etc - you will need a low-power or Stereo Microscope as such specimens require lower power magnification from 6.5X-45X. By definition, a stereo microscope has at least two eyepieces (binocular), and provides a three-dimensional image of the specimen.
Optical performance is largely determined by the quality of the objective lenses and, to a secondary degree, by the quality of the eyepieces. The standard for good quality objective lenses is an achromatic lens. An achromatic lens is one that corrects the tendency of lenses to spread the focus point of light depending on its colour. for the fact that different colors refract through a lens at different angles. The achromatic microscope produces a significantly sharper specimen image than would otherwise be seen.
Finally, it is useful to ensure that the objectives are DIN compatible. While DIN (Deutsch Industrie Norm) is not a measure of quality, DIN objectives are useful since they are interchangeable from one DIN compatible microscope to another. Should you lose or damage an objective, you can easily replace it rather than have to buy a new microscope.
With regard to eyepieces, as a general rule, the wider the eyepieces the easier the viewing. Be aware, however, that higher power eyepieces have smaller eye lenses.
There are two primary types of illumination: natural daylight and artificial.
The tilting mirror fitted to many microscopes allows daylight from a window to be directed through the specimen as a suitable form of illumination. Of course, artificial light sources can also be used.
Built-in Halogen produces a strong, white light and typically, includes a variable rheostat so that the intensity of the light can be adjusted. A halogen desk lamp (of the type that can be purchased for a few pounds from IKEA or Argos!) makes a good illumination source when using a microscope equipped with a reflection mirror.
LED lighting is used in a number of our microscopes and has the advantage of being very white and operates without much heat being given off.
Flourescent lighting is typically used in specialist, flourescent microscopes for biological research and similar applications. However, fluorescent ring lights are typically used as additional light sources in stereo microscopes when more and even light is required.
We recommend against using tungsten lighting (ordinary light bulbs). They produce yellowish light that can make some detail difficult to see.
OTHER USEFUL FEATURES
Two speed course and fine focus control
A very worthwhile feature on some of our higher specification models is two stage focus control � especially useful when making high power observations � fine focus control allows the finest detail to be seen.
Iris Diaphragm & (Abbe) Condenser
The more sophisticated compound microscopes have an iris diaphragm and an Abbe condenser lens. Both items are found in the sub-stage of the microscope and are used in adjusting the base illumination.
A mechanical stage is also useful particularly when viewing specimens at high magnifications. The mechanical stage has two control knobs that allow the specimen slide to be moved very precisely in the x and y directions under the objective. If not included with the microscope this useful accessory can be purchased separately for the superior specification microscopes.