Microscopes

• Light microscopes use multiple lenses to produce an image that is viewed through the eyepiece.
• Light passes from a bulb under the stage through a condenser lens, through the specimen, through the objective lens and then through the eyepiece lens.
• Often they have four immersion lenses (x4, x10, x40 and x100).

To prepare a specimen:

• Staining: coloured stains bind to chemicals in the specimen and allow it to be seen. Some bind to specific structures (e.g acetic ocein stains DNA red).
• Sectioning: specimens are in wax which stops them from distorting when cut.

Advantages:                                                                              Disadvantages:

1) magnification to max of x1500                                             1) low resolution means we cannot  

2) resolution to max of 200nm                                                      see internal structures         

3) wide range of specimens can be viewed                                                           

4) cheapest microscope & portable