High power and low power are basically the .two types of microscope. You would use a high power microscope for looking at very tiny things bacteria, blood cells, and life in pond water, cells and insect legs. The low power microscopes are used to look at larger things like a bee, a fly, fabric weaves, coins, stamps and sand grains. On the left, sand, placed on black paper is best seen with a low power microscope. Head lice are small but visible and yet are best seen with a high power microscope. High power microscopes are the most popular. For children, hobbyists and general use, high power microscopes are most popular as one can see the truly invisible things like blood cells, amoebas and bacteria. If you are shopping for a child, do not buy a plastic toy microscope, they will do nothing but frustrate you and/or your child. Real microscopes, with metal frames and glass optics are what you want but are rarely found in stores. When shopping for children, look for a company that provides slides and support material with the microscope so your child will have some direction in using and enjoying the instrument.
High power microscopes go up to 1000X and have a light under the specimen. The light on a high power microscope must pass through the specimen for you to see an image. You would not look at a coin with a high power microscope as you would only see a black circle on a white background. For most high power applications, a maximum magnification of 400X is sufficient. There are no manufacturers of microscopes in the US nowadays.The best economy models are made in China. Some very good product is now coming from China but be careful as there are also some poorly built instruments. We have looked at many brands and can highly recommend the National Optical brand name. They are based in San Antonio, Texas, one of their dealers, carry their products and provide excellent customer service and technical support. For ages 7-12 The National Optical Model 109-L is the most popular model used in elementary schools today. With an all metal frame and glass optics, the 109-L provides crisp clear images at three powers, 40X, 100X and 400X. It is compact in size, about 12″ tall and has a 110 volt illuminator. For ages 10 – Adult, The National Optical Model 131-CLED unlike the 109-L above, the 131-CLED is a full sized instrument and measures 14″ tall. It is very popular in middle school and high school biology classes. Many adults use this model as well. The 131-CLED has an all metal frame, glass optics and a bright LED light which is cool and will not harm specimens. Hot lights can kill specimens such as protozoans that may be swimming around on your microscope slide. It has three powers of 40X, 100X and 400X and provides a bit sharper image than the 109-L. Optional accessories include a hard plastic case and mechanical stage.For ages 16 - Adult on the other hand, The Model 138-SPMS exactly like the 138 above but built to superior performance standards and with a professional built-in mechanical stage. This is more microscope than you would see in a HS biology class as it has four powers, 40X, 100X, 400X and 1000X. It includes a special focusable Abbe condenser above the light and a much smoother mechanical stage than the bolt on types used on the regular 138. For ages 16 – Adult, The Model 157 There is a big price jump when you go from a monocular to a binocular model. The previous models have one eyepiece. The 157 has binocular vision and is a true research grade microscope. It has a smooth built in mechanical stage, four powers going to 1000X. A sub stage Abbe condenser and a bright 110 volt fluorescent light.The Model 163 The 160 series offers more features than the 150 series and the 163 is a trinocular model which means that it provides binocular vision plus a third tube where you can place a camera. Lastly, Adult Digital microscopes are similar to the models above but include a built in camera in the top of the microscope. Using the USB port on your computer, the image is displayed on the screen or captured to a folder on your hard drive. Digital microscopes can be used as regular microscopes, without the computer and come complete with software, cables and calibration slide for making measurements.
