I have the Intel microscopes and it will find flukes. It gives good high
quality easy to see view, but the refresh rate is to slow to see the small
parasites that you find by movement and identify by the type of movement. I
later bought a student microscope. It has 10X eye piece and 4X, 10X, &40X
optics on the turret. A scope needs to have a built in light source and a
means of controlling the intensity seen through the scope.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html


"flyline" wrote in message
rthlink.net...
May I suggest that you look in to the computer based microscope from, I
believe, either Microsoft or Logitech. Have plenty of power and you can
zoom on-screen. Much better than the old types.

"sandra" wrote in message
...
Im looking into buying a microscope for parasite ID among other things.
Do
any of you have opinions on a good brand that will allow for 100-400
magnifications. I've seen some online for under $100 that magnify to
10x-40x. I haven't been able to figure out if that means 100-400? I have
a
jewelry loupe that I use for examination of some of the more obvious
pests
but some of my fish kept off site from my pond have a condition that I
need
to investigate further with a microscope.
Thanks in advance.
sandra

sandra wrote:

Im looking into buying a microscope for parasite ID among other things. Do
any of you have opinions on a good brand that will allow for 100-400
magnifications. I've seen some online for under $100 that magnify to
10x-40x. I haven't been able to figure out if that means 100-400? I have a
jewelry loupe that I use for examination of some of the more obvious pests
but some of my fish kept off site from my pond have a condition that I need
to investigate further with a microscope.

There are many microscopes on the market for prices as low as $20, which
claim high magnifications like 1000 x. If you ever look through them,
you will be very disapointed. These things are worse than useless,
because they kill the joy from an interesting and worthwhile hobby.

The first misunderstanding to be exterminated is that lay persons tend
to judge microscopes by their magnification. However, magnification is,
in essence, irrelevant. Important is the resolving power of a
microscope, that is the smallest distance two points may have to be
distinguishable as two separate, rather than one big, points. The
physical dimension that gives you an idea about the resolving power of a
lens is the numerical apperture (n.a. for short). Without going into the
gory details, the higher n.a. is, the better the lens. The maximum n.a.
possible for lenses in air is 1.0, 0.6 or so is a very good value.
Higher values of n.a. can be obtained by using high refractiv index
media between the lens and the object, for example immersion oil. In
those cases n.a. up to 1.3 is obtainable.

The objective lens(es) should be marked something like 40x, n.a. 0.63,
160.

That means that the lens (by itself) has a magnification of 40 times,
with an n.a. of 0.63 and is corrected for an optical tubus length of 160
mm. Microscopes where the lenses are not marked in this fashion should
not be bought, as they are (pardon) crap.

The total magnification of a microscope can be calculated as the product
of the magnifications of the (objective) lens and the occular. Above
lens, combined with a 10x occular, gives a magnification of 400x. The
total magnification should be between 500 and 1000 times n.a., in the
above example 315-630 fold. Thus the selection of a 10 times occular was
appropriate.

A 20x occular on the other hand would result in a magnification of 800
fold, which is too high for the lens. Two points that were shown by the
lens as a single blob would result only in a bigger blob, but would not
be resolved into two by the occular. We call this "empty magnification".

Appart from the resolving power of a lens there are a couple of other
things to watch out for, in particular lens errors (aberations).

The most important is the colour error (chromatic aberation). The glass
that lenses are made from diffract light of different colour
differently, resulting in coloured rims around the structures you
observe. To prevent this, the objective lenses in a microscope are not
simple single lenses, but combinations of lenses from glasses with
different refraction properties. They are then called achromatic or
apochromatic (marked on the lens for example as "apo").

Another lens error results from the fact that light rays that enter the
lens near the centre are treated differently from those entering in the
periphery. Thus parallel light is focussed not into a focus point
(infinetissimaly small), but a focus spot (of finite dimensions). This
error, too, can be minimised by lens design.

On very expensive lenses you may find a mark like "fluor", these are
made from low fluorescence glasses for fluorescence microscopy. For your
purpose they are overkill.

So what do you need? You will need a microscope that is solidly build,
from a manufacturer who offers a wide selection of add-ons, when your
needs expand (as they probably will). Objective lenses should be mounted
on a "revolver" with at least 4 places. For the beginning, use lenses
4x, 10x, 40x air and 100x oil (useful for bacteria), each with as high a
n.a. as you can afford. If the microscope is well build, you can focus
an object with low magnification, when you then switch to a higher lens,
you should be able to see the oject after minimal re-focussing. If you
have the money, go for a 40x "phase contrast" lens in addition to the
above, they are useful for live (unstained) specimens.

A good 10x "wide field" occular (eye piece) gives you magnifications
between 40x and 1000x. Some occulars are marked with a spectacle, those
allow your eyes to be further away from the occular during observation.
Even if you do not wear glasses, this is handy and does not cost more.
You can get microscopes with one (monoccular) or two (binoccular) eye
pieces, the latter are more comfortable for long term observations, but
obviously more expensive. It is possible to change between monocular and
binocular tubi on a microscope (or even trinoccular for mounting a
camera), so you can buy a monoccular at the beginning.

The object stage should be sturdy and be adjustable in x,y-direction
with a micrometric ("nonius") scale. This allows you to find again
interesting points in a sample.

Below the object stage you will find another lens system, called
condenser. This should be hight-adjustable.

Simple microscopes used in biology classes use "critical illumination",
they are easy to use and (relatively) cheap ($600-1000 for a decent
instrument). If you want to do micro-photography, you should go for a
microscope with "Koehler illumination", starting at about $1500 for a
simple and several 10,000 for a full blown research microscope. For a
beginner, critical illumination should do. Unfortunately, it is at least
difficult to change to Koehler later without buying a completely new
microscope.

Somebody with experience in microscopy will probably have test objects.
Those are slides with diatoms mounted on them. The fine structures of
diatom shells are visible only if the lenses are of decent quality, lens
errors are also easily identified. Such a person can also show you how
to use your new tool without damaging it, and how to prepare samples for
best effect. Some cities have microscopy associations, where help can be
obtained. Aquarium associations may have some knowledgeable persons too.
Biology teachers are another possible source of help. Your local library
may have books on microscopy, which are worthwhile.

so it you have a 10X eye piece and a 40x objective you get 400 magnification
Bob
Talking to himself again

"Robert Flory" wrote in message
.com...
10X = ten magnification 40x=40 magnification
"sandra" wrote in message
...
Im looking into buying a microscope for parasite ID among other things.
Do
any of you have opinions on a good brand that will allow for 100-400
magnifications. I've seen some online for under $100 that magnify to
10x-40x. I haven't been able to figure out if that means 100-400? I have
a
jewelry loupe that I use for examination of some of the more obvious
pests
but some of my fish kept off site from my pond have a condition that I
need
to investigate further with a microscope.
Thanks in advance.
sandra

that is all that is needed for typical GF diseases. bacteria need to be stained and
even then, it isnt enough information in the scope. flukes are seen at 4X and 10X,
costia and such at 10X. it is the kind of movement that will tip off what it is.
Ingrid

"RichToyBox" wrote:
bought a student microscope. It has 10X eye piece and 4X, 10X, &40X
optics on the turret. A scope needs to have a built in light source and a
means of controlling the intensity seen through the scope.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
List Manager: Puregold Goldfish List
http://puregold.aquaria.net/
www.drsolo.com
Solve the problem, dont waste energy finding who's to blame
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Unfortunately, I receive no money, gifts, discounts or other
compensation for all the damn work I do, nor for any of the
endorsements or recommendations I make.

correct. Ingrid

"Robert Flory" wrote:

so it you have a 10X eye piece and a 40x objective you get 400 magnification
Bob
Talking to himself again


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
List Manager: Puregold Goldfish List
http://puregold.aquaria.net/
www.drsolo.com
Solve the problem, dont waste energy finding who's to blame
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Unfortunately, I receive no money, gifts, discounts or other
compensation for all the damn work I do, nor for any of the
endorsements or recommendations I make.