Photography through a microscope
Amateur microscopes and cheap cameras
A simple toy microscope and a disposable camera can team up
to make stunning photographs of very tiny things.
The technique is simplicity itself. You simply focus the microscope
carefully by eye as you would normally do. Then you place the camera
lens right up against the eyepiece, and snap the picture.
[Click on photo for larger picture]
The results are suprisingly good.
Basswood (Tilia) stem, 4x objective.
[Click on photo for larger picture]
These photos were taken with an $8.00 disposable camera.
While the camera's optics are clearly not designed to compete
with expensive cameras, the images hold up to close examination,
as you can see if you click on the image to get a large view.
Basswood (Tilia) stem, 10x objective.
[Click on photo for larger picture]
The main drawback to the disposable camera is the fixed focus.
Later we will see the results of using a camera that can adjust
the focus to take sharper pictures. But the better camera costs
100 times as much as the disposable (although a $100 dollar camera
would probably take excellent pictures).
Wheat kernel, 4x objective.
[Click on photo for larger picture]
The photos were developed normally, and scanned using an inexpensive
color scanner (about $40.00).
Wheat kernel, 10x objective.
[Click on photo for larger picture]
Wheat kernel, 40x objective.
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A selection of microscopes
The microscope shown in the photo
below is an inexpensive microscope
of the type commonly sold to amateurs
like us. It has no optics under the stage except a concave mirror.
It has three objective lenses, and a single eyepiece, for magnifications
of 40 times, 100 times, and 400 times. This one is made by a company
called Labo, and I think I paid about $100.00 for it.
[Click on photo for larger picture]
Better microscopes give better results. The next step up is a microscope
with a
substage condenser.
The microscope shown below is made by Eagle, and is about $300.
It has several important improvements.
Below the stage where you place the slide, there is a large lens
system called a
condenser. This system of lenses focuses
the light onto the specimen.
[Click on photo for larger picture]
A substage condenser makes the images sharper, and allows more
control of the illumination. We will discuss how it works later.
In addition to the condenser, this microscope has a mechanical stage.
This is a device for holding the slide that allows the operator to
turn two knobs to smoothly move the slide left and right,or up and down.
Lastly, this microscope has interchangeable eyepieces, so the operator
has a choice of a wide field of view, or a closeup of the subject. This
feature is not as important as the substage condenser, since a higher
power eyepiece will not show more detail (to do that you use a higher
power objective lens). It is like blowing up a photograph. It makes
it easier to see some parts of the image, but you don't get more information.
The next step up in amateur microscopes is shown below.
[Click on photo for larger picture]
This is the Celestron Research Microscope, and it sells for about $700.
The Celestron adds binocular eyepieces, an illumination lamp, and an
oil immersion objective lens that allows 1000 times and 1500 times
magnifications.
Professional microscopes add features such as
phase contrast,
differential interference contrast, laser scanning confocal
imaging systems, epi-fluorescence microscopy, and other features
that greatly enhance the ability to see structures and features of
very small things. Some manufacturers of these microscopes are
Nikon and Carl Zeiss. In general, these microscopes have prices
a little beyond the range of the normal amateur.
Using digital cameras
Disposable cameras are nice because they are cheap, and they have
small lenses that make it possible to simply aim them down the
eyepiece and snap a picture.
More expensive cameras generally have larger diameter lenses, making
life more complicated. The lenses must be shielded from light getting
in around the eyepiece, and usually some sort of macro lens must be used
to make the eyepiece fill the photo.
The more expensive Single Lens Reflex cameras have an advantage, however,
in that they have
through the lens viewfinders, so you can see
exactly what the picture will look like before you click the shutter release.
The problem with film cameras though, is that you must wait to have the
film developed. With digital cameras, you can get immediate results.
Many inexpensive digital cameras have small lenses that are a good match
to the size of the eyepiece of the microscope, and they often have
electronic viewfinders that show you exactly what the camera sees as you
take the picture.
One digital camera I like to use for microphotography is the Camedia 2020
from Olympus (or its big brother the 3030). The Camedia takes pictures
of reasonable resolution (1600 pixels by 1200 pixels for the 2020, and
2048 by 1536 for the 3030). They also can take short movies, which we will
experiment with later.
Some digital photomicrographs
The photos below were taken with the Camedia 2020, in high resolution
mode (1600 by 1200 pixels). The pictures were cropped to eliminate
much of the black border around the eyepiece.
Basswood (Tilia) stem, sectioned and stained, 4x objective.
[Click on photo for larger picture]
Same slide, 10x objective.
[Click on photo for larger picture]
Frog blood, 40x objective.
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Onion skin, 10x objective.
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Pumpkin stem, sectioned and stained, 4x objective.
[Click on photo for larger picture]
Pumpkin stem, sectioned and stained, 10x objective.
[Click on photo for larger picture]
Pumpkin stem, sectioned and stained, 40x objective.
[Click on photo for larger picture]
Comparing microscopes
An amateur on a budget will want to know just what an extra
few hundred dollars will buy in the way of better photos.
Below are some comparison photos, showing the difference between
the $100 Labo microscope, and the $700 Celestron.
The Labo has no substage illuminator, so the slides were examnined
with the concave mirror reflecting a bright cloudy sky onto the
slide.
The Celestron's illuminator was used, which caused the colors to be
bluer than those of the same slide illuminated by bright clouds.
All photos were taken with the Camedia 2020 in high resolution mode.
Since the actual magnification is a function of the eyepiece, the
camera lens, and the settings of your monitor, rather than give a
guess at how much the image is magnified, I will instead give the
power of the objective lens, which is what determines the
resolving power, or the amount of detail that can be seen.
Paramecia stained, 4x objective.
[Click on photo for larger picture]
On the left side, the Celestron shows a little more detail, but the
difference is actually quite small. For low magnifications, the
inexpensive microscope holds its own quite well.
Paramecia stained, 10x objective.
At higher magnification, the Celestron (left) shows better contrast
and sharper detail.
Paramecia stained, 40x objective.
[Click on photo for larger picture]
With the 40 power objectives, the value of the substage condenser
begins to show. The Celestron shows more detail, and the contrast
between the macronucleus and the rest of the cell is higher. However,
the inexpensive microscope is still doing an outstanding job with these
stained slides. The use of stains to enhance contrast can make up for
a lot of missing optical resolution.
Paramecia stained, 100x oil immersion objective.
[Click on photo for larger picture]
The Celestron has a 100 power oil immersion objective that the
other microscopes lack. At this resolution we can start to see
structure in the macronucleus, especially when focusing in and
out through the depth of the structures.
Controlling contrast
Most of the work in microscopy is aimed at increasing the contrast
between the subject and the background. One of the earliest tricks
(probably used by the first microscopist, Antonie van Leeuwenhoek) is
dark field illumination.
You have used this trick to see small details without a microscope
any time you have watched dust motes in a sunbeam.
The dust motes are illuminated by bright sunlight, but the dark
background is not. The contrast between the bright dust and the dark
shadows allows you to see the dust that is normally invisible.
There are two main methods for achieving dark field illumination
in a microscope. For low powers, where the distance between the
objective lens and the subject is relatively large, you can simply
aim a strong light down at the subject, and remove any light coming
from below.
For higher magnifications, where the objective lens is almost
touching the subject, this method will not work. What is done
instead is to make use of the substage condenser and a small
black dot placed between the condenser and the source of light.
Mosquito larva, bright field illumination.
[Click on photo for larger picture]
Mosquito larva, dark field illumination.
[Click on photo for larger picture]
The condenser projects the image of the black dot onto the
objective lens, so the background is dark. However, the light
from around the edges of the black dot is focused on the
subject, and fine details catch the light and are clearly
visible against the dark background.
Video through the microscope
Earlier I had mentioned that the Camedia 2020 and
other digital cameras can take videos as well as
photographs. Below are a couple of examples. The
subjects are ostracods, a tiny crustacean found in
freshwater ponds.
[Click on photo for animated view]
For more ambitious projects, nothing beats a good digital camcorder.
The subject is a microscopic worm (possibly a planarian)
and a lot of small ciliates such as paramecia.
[Click on photo for video]
Using a video camera as a microscope.
Some cheap computer video cameras have adjustable
focus lenses that can focus almost right up to the
lens. This allows you to aim the camera straight
up, and put a microscope slide on the lens ring, and
focus on the slide.
Shown below is a Logitech QuickCam camera, facing up,
with the microscope slide on top of the lens ring.
The video shows the procedure, with a voice-over
from the author (me! Hi there!).
[Click on photo for video]
The subject is once again an ostracod (I have a bunch
of them I've been keeping as pets in a big jar for
almost 2 years now. They eat fish food.)
[Click on photo for video]
[Click on photo for video]
For more information on microscopes and photomicrography, see the
Recommended Reading
section.
Next:
Listening to Electric Fish
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