It is well possible that a particular objective belongs into several groups at the same time.
- Achromatic objectives: These are the standard objectives that can be found on most microscopes. There might be a slight chromatic aberation (color errors)
- Apochrmatic objectives: These produce extremely sharp and contrasty images. They are useful for photographic work.
- Plan objectives: Also useful for photographic work, plan objetives produce completely flat images. Conventional objectives might have the sides of the field of view out of focus, when the center is in focus. Plan objectives correct for this.
- Fluorite objectives: They are used for specific applications, such as fluorescence microscopy or fine structure research.
- Phase contrast objectives: The phase contrast technique allows you to see unstained specimens much better. Tese obejctives have a phase ring included, which makes them more expensive.
- Immersion Objectives: For oil immersion and water immersion. These objectives are designed to be in contact with immersion oil or water. There is no air between the specimen and the front lens of the objective.