Natural Science Forum / Physics / Optics / May 2007

I have been reading the comments in the sci.techniques.microscopy
group and I am impressed with the high level of knowledge that Kevin
has about microscopes. Hpe he read this.

I was given a used microscope  CORRECT TOKIO of SEIWA OPTICAL, in a
very good condition http://www.seiwaamerica.com/. It was built in 1988
as it stated in the certification card which comes with it.

My Biological Microscope Model SB-BI-1

1. Total Magnification: 40X, 100X, 400X, 1000X
2. Mechanical Tube Length: 160 mm
3. Tube: 30 degree, inclined binocular tube interpupillary distance
adjustment 55-75 mm on both tubes. Dioptric distance adjustment on
both tubes, 360 º rotatable.
4. HWF 10X (FN 16.5x pair)
5. Nosepiece: Quadruple with click stops
6. Objective (Din Type) 4X (0.10), 10X (0.25), 40X (0.65), 100XOIL
(1.25)
7. Focus Adjustment: Coaxial Type/ Coarse & Fine adjustment (2 mm
travel / 0.002 mm sensitivity with safety stopper)
8. Mechanical stage 120 mm X 122 mm with coaxial handle. Travel /35
mm X 75 mm (no idea, maybe)
9. 6V/20W Halogen Lamp Transmitted illuminator with intensity
regulator
(low voltage 6V/3.5ª) Built in transformer 220-240VAC
10. Condenser: Abbe type N.A. 1.25 condenser with iris diaphragm,
filter
Rack & pinion focusing mechanism.
11. Dimensions 380mm(H)X300mm(D)X210mm(W)
12. Weight: 6.8Kg
13. Wood Carrying Case

I been making some pictures from it and now I want to improve my
Microscope with some devices, therefore I need an expert advice to buy
the following:

A. TRINOCULAR HEAD: As the original is very expensive I have found the
following offer:

from http://www.radicalindia.com/

"We can supply Trinoclar Head suitable for Saiwa Optical Microscope.

The Inclination angle is 45º, costing US$ 105.00 each (ex-factory).

Photograph attached."

Also they promise to give me the correct circular attachment as mine
is 52 mm.

Is it worth or I am wasting my money (original SEIWA trinocular head
costs US$ 400)?

B. CONTRAST CONDENSER: Their offer is:

Brand New Phase Contrast Condenser with Objectives 10x, 20x, 40x &
100x Oil with telescopic eyepiece will cost @ US$ 425.00 each Nett Ex-
Factory.

Will it make a great difference? Currently I am taking pictures which
look like the ones taken with this device using a glass with a dark
point in the filter rack of the condenser. Is it worth?

C. DARK FIELD: Also they offer me the following:

Dark-Field Attachment @ US$ 274.00 each

Consists of dark-field condenser and 100x oil immersion with built-in
iris diaphragm.

I am asking for an advice because I am completely ignorant in this
subject and I have no place to ask.  Any comment from you will be
appreciated.

Thanking you in advance.
__________________________________________--

Stjepo,  Thanks for the kind thoughts.  If you just want to have fun then
you a microscope to have fun with, real cheap and very poorly built.  If fun
includes dropping microscopes out of windows, this is the one to use.  On
the other hand this is *very* poorly designed and made.  No one in their
right mind makes 160mm microscope anything any more, buying more 160mm for
anything serious, like hobby microscopy, is a bad idea.  I have never seen
either a Radical or a Seiwa and I want to keep it that way.

Now what I'd recommend is buying used.  Find a good microscope from any
quality manufacturer (Olympus, Nikon, Carl Zeiss or Leica) and build from
there.  Now it may be a 160mm instrument but the objectives were well made
and you can get things like 60X objectives, super wide field eyepeices and
high performance objectives if you look carefully.

On to dark field.  A hobby is all about having a good time.  If dark field
makes you happy, buy dark field, if actually seeing the specimen makes you
happy dark field is of no use.  My customers don't use dark field.  The one
use I had quit using it because there are easier way to do their technique.
One problem with dark field is false negatives, DF has tons of problems with
false negatives.  Thats what led to dark field being abandoned by 1970 for
all intents and purposes.

The microscope you have has is a student instrument at best, its a bad
imitation of the Olympus CH-B, its made to be used, and beaten up, about 3
hours a day.  The illumination isn't enough for bright field much less
anything else.  You might want to move up to something really good and long
lasting.

Thanks again!

Kevin Cunningham
SMS