# What controls the amount of light that reaches the specimen?

## What controls the amount of light that reaches the specimen?

Iris Diaphragm

### What controls the amount of light reaching the specimen and ocular lens?

Iris Diaphragm controls the amount of light reaching the specimen. It is located above the condenser and below the stage. Most high quality microscopes include an Abbe condenser with an iris diaphragm. Combined, they control both the focus and quantity of light applied to the specimen.

What part of the microscope controls the amount of light shining on the specimen?

iris diaphragm

What part of the microscope adjusts light?

## How does the depth of field change with magnification?

The depth of field is a measure of the thickness of a plane of focus. As the magnification increases, the depth of field decreases. Higher magnification means the light is bent more. At a certain point, the light is bent so much that it can’t make it through the objective lens.

### What magnification has higher depth of field 4X or 10X?

Table 1 – Depth of Field and Image Depth

Magnification Numerical Aperture Depth of Field (µm)
4x 0.10 55.5
10x 0.25 8.5
20x 0.40 5.8
40x 0.65 1.0

What happens to the depth of field as total magnification decreases?

Decrease magnification? The less overall thickness you can see, so the depth of field is less. Lower the magnification, the greater the thickness you can see, so the greater the depth of field.

Did the size magnification increase or decrease?

The light intensity decreases as magnification increases. There is a fixed amount of light per area, and when you increase the magnification of an area, you look at a smaller area. So you see less light, and the image appears dimmer. Image brightness is inversely proportional to the magnification squared.