BIO130 Lab 1 Exercise 3 The Microscope

Parts of the Microscope, Light Adjustment, & Diopter

Measuring Field Diameter Using the Stage Micrometer:1. Insure that left ocular lens is turned fully counterclockwise

(Lens should be as tall as it can be)2. Focus on the stage micrometer3. Measure the diameter (widest part) of the field of view

using the tiny millimeter ruler of the stage micrometer using only your left eye in the left ocular

40X Magnification

100X Magnification

Line up the 0.0 line on the edge of the visible field: the zeros will no longer be visible

Read off where the ruler ends on the other side: this one looks like 1.745mm Each scope is a little different

400X Magnification

Using field diameter to determine the size of an object specimen feature or cell:

1. Know the field diameter of the objective lens you are looking through. (We measured this)

2. Center and focus the object.3. “Guess” how many of that object would fit end to end

across the diameter of the field. (Diameter = the widest part of the circle of light you see through the lens)

10X objective: diameter measured to be 1860µm

1860µm

Looks like 2 would fit across

Using field diameter to determine the size of an object specimen feature or cell:

4. Divide the field diameter by the number of objects you think would fit across end to end to determine the size of one of the objects.

10X objective: diameter measured to be 1860µm

1860µm

Looks like 2 would fit across

1860µm ÷ 2 = 930µm

New object:New object:

10X objective: diameter measured to be 1860µm

1860µm

Looks like 4 would fit across

1860µm ÷ 4 = 465µm

The green oval is approximately 465µm long

Which lens do I use?

The object is a fixed size, regardless of lens you should get the same answer!

Use the lens that allows you to see the whole object the best: big enough to guestimate how many fit across the diameter, not too magnified that you cannot see the whole object in the same field.

10X objective: diameter measured to be 1860µm

1860µm

Looks like 4 would fit across

1860µm ÷ 4 = 465µm

465µm

40X objective: diameter measured to be 465µm

Looks like 1 would fit across

465µm ÷ 1 = 465µm

This object (green oval) is 465µm: you should get approximately the same answer which ever lens you use.

Dogfish Placoid ScaleDogfish Placoid Scale 4X objective(40X)

10X objective(100X)

40X objective(400X)

Measure one diamond

http://relentlessthirst.files.wordpress.com/2009/02/dogfish1.jpg

http://www.elasmodiver.com/Sharkive%20images/Spiny-dogfish-070.jpg

DinoflagellateDinoflagellate 4X objective(40X)

10X objective(100X)

40X objective(400X)

Don’t cut off his tails!

Red Tide

http://www.sciencedaily.com/images/2007/08/070830150106-large.jpg

http://www.pac.dfo-mpo.gc.ca/fm-gp/contamination/Images/Red%20Tide%20-%20Mary%20Mackin%202.jpg

Human Cheek CellHuman Cheek Cell 4X objective(40X)

10X objective(100X)

40X objective(400X)

Large irregular shaped cells: look like a ruffled sunny side up egg

Human Blood SmearHuman Blood Smear

WBC

RBC

4X objective(40X)

10X objective(100X)

40X objective(400X)

Tiny red dots, even with the 40X objective: guestimate carefully!

Dogfish Placoid ScaleDogfish Placoid Scale DinoflagellateDinoflagellate

Human Cheek CellHuman Cheek Cell Human Blood SmearHuman Blood SmearWBC

RBC