GUIDE · MICROSCOPES

Buying microscopes for a microbiology teaching lab.

Microscopes are usually the largest single purchase in a teaching lab, and they last for years. This guide helps you settle what you need before you request quotes, so you can compare offers on the things that matter.

1. Start with what students need to see

The course decides the optics. Stained bacteria are the deciding case in most microbiology courses: resolving them needs a 100× oil-immersion objective. If any lab exercise involves Gram stains or other stained bacterial smears, every student microscope (or every one used for those exercises) needs one.

Check your lab manual and syllabus against this table before deciding anything else. ASM's curriculum guidelines include microscopy among the laboratory skills students should develop.

2. Work out how many you need

For microscopes, the count is about how many students are at the bench at the same time, not total enrollment.

• Seats per section: one microscope per student, or one per pair? Pairs halve the cost but halve each student's time at the eyepieces.
• Overlapping sections: if two sections ever run at once, you need enough for both.
• Spares: plan for one or two instruments out for repair at any time, so a broken one doesn't leave a student without a microscope.
• What you already own: count only instruments that meet the specification below and work reliably.

The item planner does this arithmetic for you: enter the microscopes you need as "units required", the working ones you own as "usable stock", and a pack size of 1.

3. The specification that matters

Most of what separates a frustrating teaching microscope from a good one comes down to a few lines on the quote. Ask every supplier to state each of these.

Background on numerical aperture and condensers: Evident Scientific, "Numerical Aperture". Oil immersion is needed because air limits a dry objective to an NA below 1.0.

4. Classroom durability

Teaching microscopes are handled by many inexperienced users. These features reduce damage and loss.

• Spring-loaded (retractable) 40× and 100× objectives, so a lens driven into a slide retracts instead of cracking the slide or the lens.
• A focus stop or tension control, so the stage can't be raised into the objective or drift down during use.
• Locking eyepieces and objectives, if equipment goes missing in your setting.
• A carrying handle, cord storage and dust covers, because microscopes move between storage and benches every session.
• Focus mechanism construction: ask what the gears are made of and what the warranty says about them, since focus mechanisms take the most wear.

5. Service, parts and running costs

• Warranty length, and what it excludes (optics, electronics, damage from use).
• Whether repairs are done locally or the instrument must be shipped away, and for how long.
• Availability and price of replacement objectives, eyepieces, LEDs and stage parts.
• Whether the supplier offers cleaning or servicing visits, and their cost.
• Running costs to include in your semester budget: immersion oil, lens paper and cleaning solution, slides and coverslips, and staff time for cleaning and maintenance.

6. Optional extras

• A camera or trinocular head on the instructor's microscope, so a specimen can be shown to the whole class.
• Phase contrast or darkfield, if live, unstained organisms are part of the course.
• Storage cabinets that keep instruments covered and secured between sessions.

7. Printable worksheet

Print this page (Ctrl+P or ⌘P) and fill in the table below for each quote you receive. For comparing costs, delivery and terms in more detail, see comparing supplier quotes. Choose "Save as PDF" in the print dialog to keep a digital copy.

Where to request quotes

Your institution may already have approved suppliers or contract pricing, so check with your purchasing office first. The supplier research section on the planner lists educational suppliers to start with. Those are ordinary, unpaid links.

Last updated 9 October 2026.