Customer Service:  +1 800-766-7000Web Support:  +1 877-885-2081All Other Contact Info

  

Microscopes FAQ

From concept and design through manufacturing and customer service, Fisher Scientific lab equipment meets the highest quality standards. Fisher also provides outstanding customer support, with expert customer representatives across the United States. Click on any of the sections below to see answers to the most frequently asked questions about Microscopes.

 

Optics

Videomicroscopy and Photomicroscopy

General Mechanical and Miscellaneous

Reticles and Eyepiece Micrometers

Illumination and Contrast Systems


Optics


Q

What's the difference between phase contrast and planachromatic?

A

"Phase contrast" is a light baffling technique used to induce contrast in unstained and unmounted specimens.

"Planachromatic" describes an objective lens system which has been corrected for chromatic (achromatic) and spherical (plan) aberration. Almost all microscopes today are achromatic, which simply means that they automatically correct color errors, providing accurate specimen representation. However, correcting spherical aberrations requires an additional feature which may be somewhat expensive. Objectives which are not specified as "plan" will show a field that is in focus in the center, but out of focus at the periphery, which can be problematic for scientists who try to scan an entire field, or who spend prolonged periods using the microscope. In contrast, plan-achromatic fields automatically correct color and spherical aberration, which means the entire image is in focus, right to the edges of the field.


back to top

Q

What is the difference between primary magnification and total magnification?

A

Primary magnification is the magnifying power of them microscope's objective lens system, while total magnification is the product of the primary magnification and the eyepiece magnification. For instance, a microscope equipped with a 40x objective and a 10x eyepiece has a primary magnification of 40x and a total magnification of 400x.


back to top

Q

I want to look at an object at 400x or 1000x, but the object is opaque. How can I illuminate it?

A

You can accomplish this by using the epi-illumination (light from above) system in a metallurgical microscope. Fisher Scientific offers two simple metallurgical microscopes, which differ from biological microscopes in that the light source is abovethe specimen.


back to top

Q

I want to buy 15x eyepieces to use with my 100x objective. Will they improve my scanning ability?

A

Fisher Scientific offers 15x eyepieces that will increase your magnification. However, your true magnification power is limited by the numerical aperture (NA) of your condenser. For example, if you are using an Abbe condenser with a 1.25 NA, the true optical magnification is limited to 1250x. Any magnification beyond this level is considered "false" magnification, which means the resolution will not improve once you move beyond 1250x.


back to top

Q

What is the resolving power of Fisher's 100x objective?

A

The best stated resolving power is fairly standardized at 1 micron (0.001mm). While you can actually see particles smaller than this using a 100x objective and 15x eyepieces, the optical integrity of the image will be questionable.


back to top

Q

Can I add a 100x objective to my new Micromaster III?

A

No. You'll need an Abbe condenser with a 1.25 NA condenser. We are adding an optional stage system, which will allow this upgrade; call your customer service representative for more information.


back to top

Q

I want to buy a replacement objective for a non-Fisher microscope. Are your objectives compatible with other manufacturers'?

A

This depends on the brand and model of the microscope. Fisher Scientific sells DIN standard objectives, which will work in the majority of microscopes but not in all systems. Find out whether your microscope uses DIN standard optics, infinity corrected optics, JIS standard optics, or some other system. If your microscope uses DIN standard objectives, Fisher's objectives will work. If not, call us for more information.

 

Below is a list of some common microscopes, as well as the kind of objectives needed:



  • Leica ATC2000
  • Leica (B&L) Galen III
  • American Optical 110, series 10, series 410
  • Zeiss KEF, Standard 16
  • Olympus CH series
  • Olympus BH series
  • Olympus BX series
  • Nikon Alphaphot
  • Nikon Labophot
  • Swift microscopes
  • Meiji microscopes
  • Infinity corrected optics
  • DIN standard optics
  • Infinity corrected optics
  • DIN standard optics
  • DIN standard optics
  • Most are DIN standard optics
  • Infinity corrected optics
  • DIN standard optics
  • Most are DIN standard optics
  • DIN standard
  • Most are DIN standard optics


back to top

Videomicroscopy and Photomicroscopy


Q

What's the magnification of Fisher's video inspection system?

A

The primary—or objective—magnification is 0.2x to 0.7x at a 140mm working distance; final magnification is dependent on screen size.

However, field of view is probably more important than total magnification. At high magnification, with a doubler lens (140mm working distance, 13-inch monitor), Fisher's video system has a field of view of about 3.5mm and a resolution of approximately 15 microns (0.015mm). At low magnification (140mm working distance, 13-inch monitor), the Fisher system has a field of view of 34.5mm and a resolution of 130 microns (0.13mm).

If you're trying to look at a specimen that is 50 microns across (0.050 mm), Fisher's system should work, because it is able to "resolve" particles as small as 15 microns. If the object is 15 microns or smaller, you'll need a higher magnification system.


back to top

Q

What do I need to attach a 35mm camera to a Fisher microscope?

A

You'll need a T-mount adapter and a T-ring. The T-mount attaches to the microscope, while the T-ring, which is brand- and model-specific, attaches to the camera. The T-mount and T-ring are then connected via a standard thread. With Fisher systems, the T-mount is also microscope-specific. Fisher offers one model for the Micromaster I, Micromaster II, and phase contrast microscopes; another model sold by Fisher fits the trinocular Stereomaster zoom microscopes. Fisher's systems do not attach to the outside of an eyepiece.


back to top

Q

I'm using a microscope for photography and need a 100/150 watt light source. Can Fisher Scientific help me?

A

Fisher has just begun to offer a new system that is equipped with a high-power halogen light; call your customer service representative for more information.

Many times these systems will not be necessary because our trinocular heads have slide-out main prisms.


back to top

Q

How can I attach a video camera to a Fisher microscope?

A

You'll need a camera with a power supply, a microscope adapter, cabling, and a video monitor. Fisher Scientific sells these components as systems to make ordering as easy as possible, with everything included except the monitor. Fisher also sells these items separately, in cases where the customer already has a camera.


back to top

Q

Can I use a regular television screen instead of a video monitor?

A

Yes, if you have the right type of television and are willing to accept a lower-resolution screen image. We recommend a system with at least 400 lines for best image; most consumer televisions have only 200 to 150 lines, but this lower resolution is fine for many applications.

Your television must have an RCA-type jack on the back labeled "video in." You will not be able to use the coaxial jack for your antenna or cable line.


back to top

Q

Do I need a trinocular microscope to create a video microscopy system?

A

No. Fisher's microscope video adapters slide into the standard eyetube of just about any compound microscope. (Please call for more information on stereo microscopes, which are more complicated.)

You can even attach a video camera to a small student microscope such as the Micromaster III. However, the camera tends to make a smaller microscope top-heavy and unstable; for this reason, we recommend using a dual-view or trinocular microscope for these applications.


back to top

General Mechanical and Miscellaneous


Q

How often do I need to have my microscope serviced?

A

We recommend that you have a qualified Fisher service technician examine, clean, and relubricate your microscope every 6 to 12 months, depending on how often you use it. A microscope that is used constantly will have a much longer life if you have it serviced twice each year.


back to top

Q

What is the function of an iris diaphragm?

A

The iris diaphragm induces contrast in a specimen and may be the single most important control on a compound microscope. If you fail to adjust the iris diaphragm, your specimen may appear washed out or even seem invisible. Many people believe the iris diaphragm is used to adjust light level; while it can be used for this, that is not its primary function.


back to top

Q

What is the advantage of a reversed nosepiece?

A

A reversed nosepiece makes it easier to manipulate and exchange slides without bumping the objective on your microscope. Not only is this more convenient for you, but it also helps to keep the optics clean.


back to top

Q

What is a dual-view head?

A

A dual-view head is a microscope with one vertical eyetube and one inclined eyetube, commonly referred to as a teaching microscope. The inclined eyetube is used for direct observation, while the vertical eyetube can be used for a camera or a second eyepiece.


back to top

Q

What is a dual-head or multiple-head microscope?

A

These systems include one high-quality microscope with a very powerful light source which sends an image to two or more binocular heads, connected with optical tubes. This type of microscope enables several users to view a single sample simultaneously. Dual- or multiple-head microscopes also may include a movable pointer mounted just above the objective, which appears in each of the heads.


back to top

Q

Do Fisher microscopes have locked-on eyepieces? Is there an advantage in this?

A

Fisher's student (Stereomaster) microscopes feature locked-on eyepieces, while our professional microscopes do not. Locked-on eyepieces offer significant benefits in teaching environments, where removable eyepieces may be lost or broken.


back to top

Q

Do Fisher Scientific's trinocular microscopes have slide-out main prisms? If so, what is the percentage when the camera is in main prism mode?

A

Yes. Fisher's trinocular microscopes feature slide-out main prisms which, when in use, offer 100 percent/0 percent or 0 percent/100 percent options. Either all the light can be sent to the eyepiece, or all the light can be directed to the vertical tube where the camera is positioned.


back to top

Q

What is the reach on Fisher's boom stand system?

A

The usable reach is 22.5 inches.


back to top

Q

What is the plate size and usable area for Fisher Scientific's pole stand system?

A

The base plate on this system is 10 inches by 17 inches, with a removable 3-inch-diameter stage plate. The usable space on the pole stand is approximately 10 inches by 10 inches. A transmitted light source can be added to the pole stand in this system.


back to top

Reticles and Eyepiece Micrometers


Q

What is a reticle?

A

A reticle is a flat piece of glass printed with a pattern. When the glass is mounted in a microscope eyepiece, the pattern is superimposed over the image of the specimen being studied. Using a reticle, microscope operators can superimpose the image of a crosshair, linear micrometer, or grid over their specimens. Crosshairs are used primarily for positioning, linear micrometers are used for measurement, and grids are used for counting.


back to top

Q

How is a linear micrometer used for measurement?

A

Once it is installed in the eyepiece of your microscope, the reticle must be calculated at each magnification to ensure accurate measurement. If the micrometer you're using has 100 divisions, you'll need to know what each of these divisions is equal to, in terms of distance, at every magnification you'll be using. Since the reticle is mounted in the eyepiece, its size will not appear to change when you change objectives. For example, if you are using a 4x objective, each division may equal 50 microns, while at 100x each division may only represent 3 microns.

To perform the needed calibration, you'll need a stage micrometer or a calibration plate, essentially a tiny ruler mounted on a glass slide. Place the calibration plate on the stage and focus the ruler, aligning the edge of one of the linear micrometer's divisions with the edge of one of the calibration plate's divisions. Now calculate the relationship between these measures and record this information, repeating the process for each of your microscope's objectives. When you're ready to measure specimens at different magnification levels, simply refer to this information to ensure a correct measurement.

For zoom optical systems, this calibration can be done at high and low magnifications. For intermediate settings, calibration should be performed each time the zoom adjustment is changed and a new measurement is made.


back to top

Q

What is the cost and complexity involved in adding a pointer to my microscope's eyepiece?

A

Adding a pointer is easy and inexpensive; most pointers sell for about $5.00 and simply slide into the bottom of the objective.


back to top

Illumination and Contrast Systems


Q

What is "darkfield?" What applications should it be used for?

A

Darkfield is a system of illumination which is the opposite of brightfield. In darkfield, the background is black and your specimen appears luminescent. Darkfield works by imposing a black background directly behind the sample and introducing light from the side of the sample. This illumination system is ideal for low-contrast or unstained specimens which would be difficult to see against a white background.


back to top

Q

What is "phase contrast," and how does it work?

A

Phase contrast is a light baffling technique used to induce contrast in unstained and unmounted specimens. It works by incorporating two light filters, or phase annuli, which complement one another.

The lower annuli mounts below the Abbe condenser and blocks all light except that from the very perimeter. The second annuli, which is the mirror opposite of the lower annuli, is mounted within the body of the objective. These two annuli are aligned with each other to block out any direct light, and instead send indirect refracted and diffracted light to the specimen. The phase contrast technique produces a better-contrasted image for wet mount specimens.


back to top

Q

What are the key differences among tungsten, incandescent, quartz, and halogen quartz lighting?

A

Tungsten and incandescent mean the same thing, while quartz and halogen quartz refer to a different kind of light. Halogen light (or quartz light) is more intense and has a higher color temperature, which means that the resulting light is very white. For that reason, it is widely considered the best type of illumination for microscopy.

Incandescent light has a lower color temperature, which means it is more yellow in appearance. It is much less expensiveto incorporate incandescent light into a microscope; therefore, incandescent or tungsten light is more commonly found in lower-cost microscopes.


back to top