When immersion objective is being usedto view bacteria?

Question

When immersion objective is being usedto view bacteria?

Answer 1

It is used only when you need to look at individual bacteria, not colonies. Colony characteristics can be judged by naked eye, but for example "gram staining" requires individual bacterium to be observed therefore you need a high magnification objective. Highest magnification objectives are almost always oil immersion type.

Answer 2

For most of the times oil  immersion objective is used for viewing bacterial cells as they cannot be seen at the lower magnification. Oil immersion objective provides maximum magnification to observe the bacteria.

Answer 3

Just about always. Most are only visible at the highest magnification.