![\"types](\"https:\/\/scopedetective.com\/wp-content\/uploads\/2021\/01\/types-of-objectives.jpg\")
But most commonly, when talking about types of objective lenses we are referring to the different magnifications and purposes of the four most common types of microscope objective lenses on compound light microscopes.<\/p>\n
Those four are:<\/p>\n
- \n
- The scanning lens (4x)<\/li>\n
- The low power lens (10x)<\/li>\n
- The high power lens (40x)<\/li>\n
- The oil immersion lens (100x).<\/li>\n<\/ul>\n
Below I outline all the types of objective lenses based on the four above means of classification. First, I\u2019ll start with the types of lenses based on magnification.<\/p>\n\n
The four most common types of Microscope Objective Lenses<\/h2>\n
The below lenses are the four most common magnification levels for objective lenses. You can get lenses with other magnification levels also.<\/p>\n
Scanning Objective Lens (4x)<\/h3>\n
![\"scanning](\"https:\/\/scopedetective.com\/wp-content\/uploads\/2021\/01\/scanning-objective-lens.jpg\")
<\/p>\nThe scanning objective lens usually has 4x magnification and can be identified by a red strip band around the perimeter of the lens.<\/p>\n
The scanning objective is designed for getting your bearings right before moving onto the low power lens. Its name, the \u2018scanning\u2019 lens, derives from the fact you are zoomed-out enough that you can scan around your specimen at this magnification level to prepare to move on to higher magnifications.<\/p>\n
Using this objective, aim to:<\/p>\n
- \n
- Achieve focus using the coarse focus knob.<\/li>\n
- Center the specimen using your fingers or the mechanical stage.<\/li>\n<\/ul>\n
A 4x magnification lens will usually achieve between 40x and 80x total magnification (with a 10x and 20x eyepiece respectively). This is the same sort of magnification that you\u2019d get with a stereo microscope, and can provide close-up magnification of visible specimens such as feathers and leaves.<\/p>\n
Low Power Lens (10x)<\/h3>\n
![\"low](\"https:\/\/scopedetective.com\/wp-content\/uploads\/2021\/01\/low-power-objective-lens.jpg\")
<\/p>\nThe low power objective lens usually has 10x or 20x magnification. You can identify it by a yellow strip around the lens housing.<\/p>\n
This objective can be very useful for viewing prepared specimens on slides. It will achieve somewhere around 100x to 200x magnification for a 10x or 20x eyepiece respectively. This sort of magnification is great for viewing small specimens like:<\/p>\n
- \n
- Fly legs<\/li>\n
- Onion skin<\/li>\n
- Brine shrimp<\/li>\n
- Hair<\/li>\n
- Skin<\/li>\n<\/ul>\n
To use this lens, first start with the red striped scanning lens to achieve focus and center the specimen. Then rotate the objective turret clockwise to the yellow striped low power lens. Next, adjust the focus with the coarse focus knob to refine your focus and the mechanical stage to re-center your specimen.<\/p>\n
High Power Lens (40x)<\/h3>\n
![](\"https:\/\/scopedetective.com\/wp-content\/uploads\/2021\/01\/high-power-objective-lens.jpg\")
<\/p>\nThe high power lens is identifiable by a blue strip around the lens housing. Most compound light microscopes are sold with a 40x magnification high power lens, although this is not always the case. You may get a 32x or 60x magnification high power lens, for example.<\/p>\n
The high power lens is used for looking at smaller specimens like bacteria and cells that are invisible to the naked eye. It\u2019s commonly used for looking at:<\/p>\n
- \n
- Mould<\/li>\n
- Cells<\/li>\n
- Germs<\/li>\n
- Tardigrades<\/li>\n<\/ul>\n
A 40x lens will achieve magnification of 400x when combined with a 10x eyepiece or 800x magnification with a 20x eyepiece. It is also very commonly used with 25x eyepieces to reach 100x magnification.<\/p>\n
Oil Immersion Lens (100x)<\/h3>\n
![](\"https:\/\/scopedetective.com\/wp-content\/uploads\/2021\/01\/oil-immersion-objective-lens.jpg\")
<\/p>\nNot all beginner level microscopes will have an oil immersion lens, and they\u2019re not really necessary for most hobby microscopy experiments.<\/p>\n
You can identify a 100x lens because it will have a white or off-white cream colored stripe around the lens housing.<\/p>\n
These lenses are called \u2018oil immersion lenses\u2019 because you usually need to use them with oil in order to view your specimen. At higher magnifications achieved with a 100x lens, there will often be too much distortion in the final image. To address distortion at high magnification levels, you can use oil immersion.<\/p>\n
Oil immersion is achieved by placing a drop of oil above your specimen, then rotating the 100x lens over the oil so the gap between the specimen and the lens is covered by oil rather than air. The light waves moving through the oil will experience less distortion than if they move through air.<\/p>\n
Total Magnification of a Compound Light Microscope<\/h2>\n
To identify the total magnification that you will achieve on a microscope, you need to multiply the magnification of the objective lens with the magnification of your eyepiece. Most microscopes come with 10x, 20x, or 25x eyepieces.<\/p>\n
Here are the common total magnifications you can achieve with common light microscope settings:<\/p>\n