Microscope Knowledge
Know your microscope objectives
Most common microscope objectives come in different types:
Achromatic objectives
Usually contain one or a pair of lenses and correct for colour and have a good flat field.
If there are aberrations they occur in the outer area of the image
Semi plan objectives
Contain one or more (achromatic) lens elements and have an extended flat field.
Semi plan objectives have an improved resolution
Plan objectives
Correct even better for colour and spherical aberration than semi plan objectives.
Plan objectives have an excellent flat field and are recommended in conjunction with a camera
Apochromatic objectives
Designed for colour and spherical aberration correction on a minimum of three wavelengths.
These objectives offer the best flat field correction
Know your microscope objectives labels
The labels on each objective explain what you have and there is a lot of consistency across major manufacturers, though not absolute
MPlanFL N - this refers to the type of objective FL is for Fluorite
50x /0.80 - this is 50x magnification and 0.80 is the Numerical Aperture (N.A) of the objective
∞ / 0/ FN 26.5 - this is infinity corrected and is now the most common design of objective
- the zero is not designed for use with cover slips
- FN 26.5 is the maximum field number eyepiece the objective is designed to be used with
The blue line also identifies as 50x objective
Know your microscope objectives labels
The labels on each objective explain what you have and there is a lot of consistency across major manufacturers, though not absolute
MPlanFL N - Options are typically Plan, some manufacturers will put an M or N in front of the Plan
50x /0.80 - options are typically 4x or 5x, 10x, 20x, 40x, 50x, 100x
∞ / 0/ FN 26.5 - in place of the ∞ you might see 160 or 180 or 210. These are the focal length design of the objective
- in place of the 0 you might see 0.17 this refers to being designed for use with cover slips
-in place of FN 26.5 you might see 20 or 22 or 23 this refers maximum field number eyepiece the objective is designed to be used with
The blue line also identifies as 50x or 40x objective other options are Brown - 2.5x, Red - 4x and 5x, Yellow - 10x, Green - 20x and White - 100x