Despite their pride and place in the field of microbiology, there are any number of affordable microscopes designed especially for the consumer market.
This is true of bright-field microscopes, and there are plenty of cost-effective models available for budding scientists. But what exactly is a bright-field microscope, and how do they work?
Bright-Field Microscopy
Bright-field microscopy is the most common form of microscope illumination. It is perhaps most notably used with light microscopes, and is the most common method of properly illuminating a slide.
Definition
The term “bright-field” comes from the way it works. The sample subject is left darker against a bright background, and thus its edges and dimensions are clearly defined.
How It Works
When we talk about a bright-field microscope, the thing that needs to be taken into account is the light path.
With light microscopes, the light path tends to be incredibly basic, requiring no other additional components. With that in mind, the light path of a bright-field microscope consists of:
- A transillumination light source - this tends to be a halogen lamp fixed within the stand, or feet, of the microscope.
- A condenser lens - this is a lens which focuses the light from the light source and onto the sample in the slide.
- An objective lens - this lens collects the light from the sample, and magnifies the image.
- A camera (or oculars) - this is the eyepiece through which the sample can be examined.
Advantages
Advantages to this kind of microscopy include the fact that it is very simple to set up and operate, and that you can easily see living cells, despite offering less magnification than more sophisticated pieces of equipment.
Limitations
The main one is the low contrast of most of the biological samples. This means that some details can be left indistinguishable from one other, but of course this entirely depends on the sample in question.
Another limitation is that once the magnification has been reached - which on most light microscopes tends to be around 1300X - there is very little room for maneuver in terms of additional lenses and magnifications.
Of course, a major limit of this technology is that sample images are always in black and white, and devoid of much of the detail you can get with say, an electron microscope.
Samples that produce their own color, such as plant cells, can be seen perfectly well without colorings or dyes, but most mammalian cells do not produce their own color, and as such can’t be seen with any degree of clarity when using a light microscope.
Enhancements & Solutions
Of course, with any limitation, there are various methods you can usually do to improve or alleviate the problem.
Firstly, you can increase clarity of details by reducing the light intensity around the iris. Similarly, oil immersion objective lenses can be used in tandem with immersion oil placed on the glass slides.
This has the same light refraction as the glass, and can improve the resolution of the sample in the slide.
You can also use a blue polarizing filter. These are capable of polarizing the light source, bringing clarity to details not usually visible under white light, such as with certain mineral samples.
Our Top Picks
Of course, despite taking the above things into consideration, finding the right product for you can still be an overwhelming task, especially with all the options available.
To help with this, we have put together a list of our top 3 bright-field microscopes to help you get the most from your purchase.
So without further ado, let’s get started!
OUR TOP PICK
Another affordable microscope, the M220 from AmScope offers quality magnification for a modest price.
With a metal body that promotes durability, the M220 has a 45 degree rear field of view, and an achromatic lens for maximum magnification.
The achromatic glass provides color correction of magnified images, and the tungsten light incorporates a 1.25NA Abbe condenser with an iris diaphragm for greater clarity.
This is a compound microscope perfect for educational purposes, and the monocular head has a 10x eyepiece, fixed 45 degree vertical inclination to ease eye and neck strain, and a 360 degree rotation to enable a more comprehensive view.
The mechanical base comes with 1.0mm stage divisions, and sturdy clips which lock into place and allow precise manipulation along the Y and X axises.
The mechanization also allows you to remotely record a specific location, so it can be easily referred to later.
Pros
- Affordable price tag.
- Sturdy metal composition.
- Mechanical stage for maximum accuracy.
- Tungsten light source.
- Achromatic lens.
- Light condenser.
Cons
- Less range of magnification.
EDITORS CHOICE
At another fairly reasonable price, the MSK-01L from C&A Scientific offers high quality 400X magnification, LED illumination, and a mechanical stage for increased accuracy.
Perfect for biological and educational applications, the 6 hole disc diaphragm allows clear examination and light control.
The mechanical stage locks into place, allowing rigidity and improved focal abilities, and the precise manipulation along the X and Y axises means that chosen spots can be remotely referred back to with little to no effort.
With a 45 degree inclined monocular head, and 360 degrees of rotation, this is the perfect all rounder for all your microscopy needs.
Pros
- Reasonable price.
- Good value for money.
- Sturdy metal body.
- Mechanical stage.
- LED illumination.
- 400X magnification.
- Clear examination.
- Light control.
Cons
- Accompanying instructions could be better.
BEST VALUE
Last, but by no means least, the B120B might be more expensive than the previous two models, but this comes with a promise of quality which has become synonymous with the AmScope company name.
With a staggering maximum magnification of 2000X, the scope is made from cast steel, has an achromatic lens for greater clarity, and a large double layer mechanical stage that allows maximum manipulation and accuracy across the X and Y axis.
The powerful single bulb light source is dimmer controlled and the 8 wide field magnification levels include: 40X, 80X, 100X, 200X, 400X, 800X, 1000X, and 2000X, allowing a wide variety of detail and adjustment.
With the wide range of maneuverability, and a 360 degree rotational ability of the inclined 30 degree head, the B120B encourages collaboration and ideas sharing during examinations.
Pros
- 2000X maximum magnification.
- Widely adjustable.
- LED light source.
- Sturdy metal frame.
- Mechanical stage for added accuracy.
Cons
- Higher price tag.
Buyer’s Guide
Before purchasing a bright-field microscope, there are various things that need to be considered.
Price
Whilst price is not always an indicator of quality, it can be a useful tool in establishing the level of quality and performance you want in correlation with the amount you wish to pay.
This can help you either find the best product for your budget (by prioritizing and isolating certain needs) or occasional needs to increase your total budget to attain the functionality you are looking for.
There are also plenty of affordable options available nowadays, all of which deliver high quality without breaking the bank.
Design
Whilst most visual appearance of microscopes tend to be similar, the design and manufacturing of the components is still important.
You want heavy duty materials, such as weighted metal bases, so as to protect it from damage or falling over.
You also want well made components that won’t malfunction or break during magnification.
Frequently Asked Question
Is Y And X Manipulation Important?
Whilst not vital for use, the mechanical manipulation of the axises allows the user to remotely return to a desired point on the sample, ensuring they don’t miss important data.
Final Thoughts
And there we have it, everything you need to know about bright-field microscopes, and the best consumer models on Amazon.com.
There are plenty of great products out there for affordable prices, meaning great equipment is no longer reserved for the experts.
Why not check some of them out?
Ever since I was a little girl, I have been fascinated by science. Every holiday I would ask for the newest science kit, and spend weeks learning with it.
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