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Q: How do I calculate microscope magnification?
A: Magnification is calculated by multiplying the eyepiece
power by the objective power. For example: A 10x eyepiece
used with a 40x objective = 400 power: 10 (x) 40 = 400x
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Q: What does "Achromat" mean?
A: Compound Microscope Optics come in 4 basic types of
"Achromat" lens systems: "Achromat" refers to the lens
being "color-corrected", these lenses have an optical
design and special coatings that eliminate or reduce color
aberrations. The objective "Type" refers to its degree
of optical correction, or degree of Flatness of the field
of view.
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Objective Type |
Degree of Optical
Correction |
| 1 |
Achromat (standard) |
60-70% Flat field |
| 2 |
Semi-Plan Achromat |
80-85% Flat field |
| 3 |
Plan Achromat |
100% Flat field |
| 4 |
Infinity Plan |
100% Flat field |
In general, as you move from # one to four, both the
image quality and cost of the optics increases. Some
companies are marketing what they term "Super High-Contrast"
objectives. Depending on the manufacturer, these are
supposed to be designed to fill the gap between semi-plan
and plan achromats (86-99% Flat field).
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Q: What does "DIN", or "DIN Standard" mean?
A: DIN refers to "Deutsche Industrial Normen", a set
of internationally accepted standards for optical systems
created in Germany. If a microscope is "DIN" it means
that its parts are designed and built to DIN standards
and can theoretically be interchanged with any other
"DIN" microscope regardless of the manufacturer.
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Q: What do the code letters and numbers on the
objective housing stand for?
A:
Degree of optical correctness: (A/SP/PL) = Achromat
/ Semi-Plan / Plan
Magnification: (40/100/400/1000) = 40x/100x/400x/1000x
Numerical Aperture or "N.A.": Refers to light gathering
capability and resolving power of the objective and
it is key to match the microscopes' condenser lens to
the highest power objective. A 40x objective should
be matched to a N.A. 0.65 condenser, a 100x objective
matched to a N.A. 1.25 condenser.
If immersion oil is required as a media for the lens,
it may list: "OIL"
Focal Length of the optical system using that objective:
40x = 160
Recommended cover slip thickness for optimal viewing:
0.17
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Q: Can you give us a sample of objective housing?
A: Here is a sample
Top Line: A / 40 / 0.65
Bottom Line: 160 / 0.17
Deciphered, this means the objective is a standard achromat,
40 power, has a 0.65 Numerical aperture, a focal length
of 160 mm, and recommended cover slip thickness of 0.17
mm.
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Q: What does the "R" after the 40x or 100x objective
specifications mean?
A: Both 40x and 100x objective housing are long
and come very close to the slide surface when in focus.
The tips of these objectives are "retractable" (R) to
prevent slide or objective damage in case the objective
contacts the slide: 40XR, 100XR.
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Q: I am having trouble focusing, what should I do?
A: While there can be a variety of causes, most
often it is a simple matter of cleaning. The typical
reaction is to assume there is something wrong with
the microscope. This is more common with oil immersion
scopes, usually the last time the scope was used with
oil, and it was not cleaned off the objective (or not
cleaned properly). It's easy to run the 40x objective
into immersion oil and not clean it, thinking you only
need to the 100x.
Most modern microscopes feature optics with a variety
of special coatings on the optical surfaces. AZZOTA
microscopes feature coatings to correct color aberrations,
glare reduction and anti-fungal.
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Q: Can I use "Windex" (or a similar) glass cleaner?
A: Consumer market glass cleaners are designed to clean
window glass in homes. Window glass generally does not
have optical coatings. Always recommend that your customers
use a good quality "optics-grade" glass cleaner, such
as a camera lens cleaner designed for use on "coated"
optics.
Another common reason for focusing problems is abrasive
cleaner and/or paper towels instead of lens paper has
been used to clean the scope. This can scratch the coatings
and/or the lens itself. This is why it is very important
to ask the customer to explain exactly how they care
for their scopes and specifically what products they
use to do so. Otherwise, you can replace the product
because of their inability to focus, and if they clean
the replacement in the same, wrong way, it will just
be a matter of time before they call again with the
same problem; and they want a replacement (or return
for refund)!
Focusing difficulties can also be caused by the "Stage
Rack Stop Adjustment" setting. This setting controls
the travel of the stage for focusing. If the rack stop
is set too high, you can easily break slides by the
objective lens crashing into the slide
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Q: Do I need Immersion Oil?
A: If your microscope is equipped with a 100x objective
(and you plan to use it), then yes, you need immersion
oil. Immersion oil accomplishes several things for the
100x objective: first, it creates a fluid lubricating
barrier between the objective lens and the slide cover
slip (viewing without the oil can cause contact between
coated glass-on-uncoated glass, resulting in slide and/or
objective lens damage); second, it eliminates the refraction
of light coming from the illuminator and focuses the light
into the objective.
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Q: What does "FN #" mean on my eyepiece?
A: FN refers to the "Field Number", or simply the diameter
in mm of the inner diameter of the eyepiece.
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Q: What kind of Illumination should I choose?
A: The three most commonly used illumination sources are:
1. Halogen 2. Fluorescent 3. LED 4. Tungsten
Halogen bulbs burn very white and bright and are an excellent
light source and give off heat making the scope fairly
warm to the touch. Halogen is an excellent choice if you
are buying oil immersion microscopes.
Fluorescent is an ideal illumination source for applications
where microscope base heat is an issue (live cultures,
etc.). The bulbs burn cool and generally last 10,000
hours plus. Fluorescent can be used with 100x scopes;
halogen is a better choice for oil work. For stereomicroscopes,
fluorescent is a great choice for viewing live cultures
without "cooking" and killing the specimens.
LED bulbs are ideal for use with battery power because
they have can provide a very bright light on a very
low power draw. LEDs can be used for 100x microscopy;
but typically more than one bulb is required to provide
sufficient light (LED 100x oil systems use 5 LED's).
Power draw is 4.5V, 3 AA batteries give exactly 4.5V.
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Q: Should I buy a "Cordless" LED microscope?
A: These microscopes have a huge advantage over traditional
scopes including the FREEDOM to take it with you anywhere!
Now more than ever, microscopes are truly portable and
can be taken out to the barn or field with no cords
or electricity required! If your customers are looking
for field use microscopes, they could not make a better
choice.
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Q: What is a "Rheostat" (or Intensity Adjustment)?
A: Many advanced microscope models featuring 100x oil
immersion objectives feature an intensity "Rheostat".
Most people know these as "Dimmer Switches" such as
you might have in your home. These rheostats allow the
user to control the illuminator power or light intensity
making the microscope more versatile in ability to view
specimens.
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Q: What is a "Blue Filter" or "Daylight Filter"?
A: Blue filters (or Daylight Filters) are used to filter
out parts of the light spectrum produced by microscope
illuminator bulbs. Using a blue filter can improve the
contrast and ability to clearly view slides. More advanced
scopes feature a "Swing-Out Filter Holder".
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Q: Do I need a Mechanical Stage?
A: For the typical 4x 10x & 40x microscopes; a mechanical
stage is not required, but would be nice. For 100x (1,000
power) a mechanical stage is essential. If you are viewing
a slide at 1,000 power (with immersion oil), and attempt
to move the slide with your fingers, a very small movement
moves you completely out of the field of view. Most
high school microscopes feature a stage with "Stage
Clips" to hold the slide on the stage. The stages of
these scopes are pre-drilled and tapped to accept an
optional add-on mechanical stage. Simply remove the
stage clips with a screwdriver and install a mechanical
stage, tighten with the thumbscrew.
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Q: Do I want "Ball Bearing" or "Rack and Pinion"
mechanical stage controls?
A: In general, ball bearing stage controls provide a
very smooth movement, superior to rack and pinion movements.
However, they are also more expensive. The answer depends
on their budget and how critical it is to have very
smooth, precision stage movement.
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Q: What does it mean to have "Coaxial" focus controls?
Coaxial focus controls on a microscope refers to the
coarse and fine focus controls being mounted on the
same axes. This is a system where two knobs, one for
coarse focus and one for fine focus are mounted together
with the coarse focus being the larger of the two, and
the smaller, fine focus knob mounted inside the coarse
knob. This feature is typically found on advanced oil
immersion microscopes.
Coaxial controls can also be found on many designs
of built-in graduated mechanical stages. This controls
the X-Y axis movement of the slide holder on the stage.
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Q: What is a "Slip Clutch" and why do I need one?
A: Slip clutches are standard on most microscopes and
they are designed to protect the objectives and slides
from damage. When the stage is raised all the way up
until the rack-stop prevents it from going further,
the tendency is for people to try and keep turning the
knob to "make" it move farther. A slip-clutch will allow
the knob to spin without moving the stage or damaging
the microscope. Many microscopes also feature a tension
control adjustment to keep the slip clutch tight.
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Q: What is "Phase Contrast" microscopy?
A: Phase contrast refers to a type of microscopy useful
for viewing transparent or translucent objects such
as live specimens or cells that have not been stained
to reveal their structure. Special objectives and condensers
are required that block portions of the illumination,
allowing exceptional viewing of otherwise transparent
specimens.
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Q: What is a Seidentopf binocular head?
A: Seidentopf heads feature an optical prism design
for adjusting the interpupillary distance by independently
being able to move either the right, or left side eyepiece
tube housings. The other common type of binocular head
is a "Sliding", or "Jensch" head.
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