Eyepiece (ocular lens)The lens you look through, usually 10x. Total magnification is the eyepiece times the objective in use, so a 10x eyepiece over the 40x objective gives 400x.
Revolving nosepiece (turret)A rotating turret that holds the objectives. Turning it changes the magnification, and each objective clicks into place when it is lined up over the opening in the stage.
Stage clipsTwo spring clips that keep the slide in place on the stage. They are fitted when a microscope has no mechanical stage, so the slide is moved by hand.
StageThe flat platform under the objectives where the slide sits. On this design the focus knobs move it up and down. Older microscopes moved the tube instead.
DiaphragmIt controls how much light reaches the specimen. On a school microscope it is a rotating disc with holes of different sizes. Closing it down raises contrast, and opening it wide gives a brighter image with less contrast.
Illuminator (light source)The light source, a bulb built into the base. Older microscopes have a mirror here instead, which reflects light from an outside source up through the stage.
ArmThe curved pillar that joins the base to the head. It carries the stage. A microscope is carried with one hand on the arm and the other hand under the base.
Coarse focus knob (coarse adjustment)Moves the stage quickly to bring the specimen roughly into focus. It is the larger knob, for the 4x and 10x objectives only. At 40x or 100x it could crack the slide or harm the lens.
Fine focus knob (fine adjustment)Moves the stage in very small steps to sharpen the image. It is the smaller knob, and the only focus knob to use with the 40x and 100x objectives.
BaseThe wide bottom section that supports the whole microscope. The illuminator is usually built into it, and one hand goes under it when the microscope is carried.
School model (left): 15 parts 5
Body tube (head)It connects the eyepiece to the objectives. It holds them a set distance apart. For most of the 20th century the standard tube length was 160 mm. Some parts lists call this section the head.
4x objective (scanning)The shortest objective has the lowest power. That is 40x in total with a 10x eyepiece. It is often called the scanning objective, because its wide view is used to find the specimen first.
10x objectiveIt gives 100x in total with a 10x eyepiece. One university lab guide calls it the most frequently used objective. It is the strongest one that may be focused with the coarse knob.
40x objectiveIt gives 400x in total. That is enough to see bacteria as small shapes but not viruses. Its tip works very close to the slide, so it is focused with the fine knob only.
Aperture (stage opening)The hole at the center of the stage. Light from the illuminator passes up through it to reach the specimen on the slide.
Lab model (middle): 7 parts 7
Diopter adjustmentA ring on one eyepiece tube. It changes the focus of that eyepiece alone. It makes up for a difference in vision between the two eyes, so both see a sharp image.
100x objective (oil immersion)The longest objective: 1,000x in total with a 10x eyepiece. A drop of oil fills the gap between lens and slide. The oil bends light about as much as glass does, so less light is scattered and more detail shows.
Mechanical stageA slide holder fitted to the stage. It moves the slide along two axes, side to side and front to back. Above 100x a slide cannot be steered accurately by hand.
CondenserA lens under the stage. It gathers light from the illuminator and focuses it on the specimen. It matters most at 400x and above.
Condenser focus knobIt moves the condenser up and down. That focuses the light on the specimen. Once set it is left alone: brightness is changed with the diaphragm or the light dial, not by moving the condenser.
Stage control knobsMove the slide side to side and front to back. Knobs below the mechanical stage. They do not raise or lower the stage, so they never change the focus.
Light intensity dial (rheostat)A dimmer for the illuminator. Images get dimmer as magnification goes up, so more light is needed with the stronger objectives.
How this list was compiled: Every part name is used by at least two of the references below, all read on 2026-09-19 for facts only, with nothing copied. (1) OpenStax Microbiology, 2.3 Instruments of Microscopy, https://openstax.org/books/microbiology/pages/2-3-instruments-of-microscopy: ocular and objective lenses, total magnification as the product of the two, the oil immersion lens and the refractive index of oil, the illuminator in the base, the rheostat as a dimmer, the condenser and its focus knob, the diaphragm, the mechanical stage knobs, coarse and fine focusing knobs, binocular heads on newer brightfield microscopes, bacteria visible at about 400x but not viruses, a dark image on a bright background. (2) Wikipedia, Optical microscope, https://en.wikipedia.org/wiki/Optical_microscope: eyepiece, objective turret, focus knobs, frame, stage, mechanical stage, light source or mirror, diaphragm and condenser, moving a slide by hand above 100x, the single lens of a simple microscope. (3) Wikipedia, Objective (optics), https://en.wikipedia.org/wiki/Objective_(optics): three or four objectives on a rotating nosepiece, the 4x scanning objective, the names small and large objective, the 160 mm tube length standard. (4) Wikipedia, Inverted microscope, https://en.wikipedia.org/wiki/Inverted_microscope: light source and condenser above the stage pointing down, objectives and turret below the stage pointing up, fixed stage. (5) Microscope World, https://www.microscopeworld.com/t-parts.aspx: eyepiece, tube, arm, base, illuminator or mirror, stage and stage clips, revolving nosepiece or turret, objectives of 4x, 10x, 40x and 100x with the shortest the lowest power, rack stop, condenser most useful at 400x and above, disc diaphragm with holes of different sizes. (6) Microscope.com, https://www.microscope.com/education-center/microscopes-101/compound-microscope-parts: head, eyepiece tube, diopter adjustment, interpupillary adjustment, nosepiece, stage clips when no mechanical stage is present, mechanical stage, aperture, iris diaphragm, condenser, condenser focus knob, illuminator in the base, lifting by the arm and the base together. (7) MicroscopeMaster, https://www.microscopemaster.com/parts-of-a-compound-microscope.html: body tube (head), arm, base, aperture, stage clips, stage control, diopter adjustment, on/off switch, mirrors on older microscopes. (8) LibreTexts, Microbiology Laboratory Manual (Hartline), 1.4 Microscopy, https://bio.libretexts.org/Bookshelves/Microbiology/Microbiology_Laboratory_Manual_(Hartline)/01%3A_Labs/1.04%3A_Microscopy: 10x oculars, the objective that clicks when it is in place, coarse focus for the 4x and 10x objectives only, fine focus at 40x and 100x, stage control knobs, the dial that regulates light intensity, condenser and diaphragm, the illuminator as a bulb built into the base, one hand on the arm and one on the base when carrying. (9) Rice University, Experimental Biosciences, https://www.ruf.rice.edu/~bioslabs/methods/microscopy/microscopy.html: the scanning lens, the 10x lens as the most frequently used, oil at the highest magnifications, contrast high with the diaphragm stopped down and low with it wide open, more light needed at high power. (10) The Biology Corner, https://www.biologycorner.com/worksheets/microscope_use.html: a class handout that names the objectives scanning (4x), low power (10x) and high power (40x). Labels, hints, detail lines, groups and position notes were written for this site. Licence: own work
The drawing: Drawn for this site, 2026-09-19. Original line drawing built from our own part list and measured proportions; nothing was traced or copied and no maker's model is shown. Read for accuracy only: Wikipedia, Optical microscope (https://en.wikipedia.org/wiki/Optical_microscope), Wikipedia, Objective (optics) (https://en.wikipedia.org/wiki/Objective_(optics)), Wikipedia, Parfocal lens (https://en.wikipedia.org/wiki/Parfocal_lens) and Wikipedia, Inverted microscope (https://en.wikipedia.org/wiki/Inverted_microscope). Licence: own work
How it works
This microscope diagram shows the parts of a compound microscope: 15 on a school model, 7 more on a binocular lab model. For a labeled microscope diagram, open Study. Find it and Name it are the microscope labeling quiz.
Read the full guide
Label the parts of a microscope
To label the microscope, switch to Name it: a ring lights and you choose from four names or type one. Ocular lens counts for eyepiece, turret for nosepiece. For a microscope diagram simple enough for a first lesson, choose Simple set: 10 parts under Start from. Or label parts of the microscope by job: 6 lenses, 6 lighting parts, 6 knobs and dials.
Light compound microscope diagram: what the words mean
Compound means two sets of lenses and light means visible light, so a light microscope diagram with labels names these parts. Bright field means a lit background: a bright field microscope diagram shows this instrument. The middle one is the binocular microscope diagram. The small one on the right, unnumbered, is an inverted microscope diagram: lamp above the stage, objectives below.
The shortest objective has the lowest power, which helps when you label parts of microscope drawings with no numbers.
Stage control knobs move the slide across the stage and never raise it, so they cannot change the focus.
The end card counts what you got right, which makes this a microscope labeling game.
Questions and answers
What are the parts of a microscope?
The school model, on the left, has 15: eyepiece, body tube, revolving nosepiece, three objectives, stage, stage clips, aperture, diaphragm, illuminator, arm, two focus knobs and base. Study is a labeled diagram of a microscope, and Name it is a parts of a microscope quiz.
Is there a compound microscope diagram with labels?
Yes. Open Study for a compound microscope labeled diagram: all 22 names written on the drawing. For a microscope diagram without labels again, press Find it or Name it.
Can I print an unlabeled microscope diagram?
Yes. Print blank leaves the microscope diagram unlabeled: rings numbered 1 to 22 and a numbered line for each, ready to use as a parts of a microscope worksheet.
Where are the microscope labeling worksheet answers?
Press Print labelled. It prints the compound light microscope diagram labeled: the same microscope diagram worksheet as Print blank, with all 22 names written in.
Why are the objectives named by number?
Our references agree on the magnifications, not the names. One handout calls the 4x scanning, the 10x low power and the 40x high power. The number is the name they share. When you label parts of a microscope by typing, low power objective still counts.