[time-nuts] Working with SMT parts.

Chuck Harris cfharris at erols.com
Thu Aug 11 16:06:13 EDT 2016

Lots of good suggestions have already been made, but for
me, a boom style stereo microscope, with a distance between
the objective, and the focal point of at least 3 inches works
fairly well...

One other thing that may force your decision, if you are
older, your eyes will likely have lots of "floaters", which
are debris that floats around in your eyeballs.  This debris
floats in and out of the center of your field of view, and
looks like a bunch of translucent worms, or shadows.

Your brain, the magnificent organ that it is, tries to compensate
for your eye's degradation, and as long as your eyes can move
about in your field of view, it effectively removes the floaters
from the scenes you are viewing.

However, if you use a stereo microscope, your eye position
is fixed by the very limited amounts of off axis motion
that will allow a through optical channel.  This lack of off
axis motion will emphasize your floaters in a great way, and you
will see *every* *single* *one*, clearly, as if it were something
you really wanted to view.  Some times, the floaters will cover
the exact thing you need to see clearly, and you will have to
move it off axis by moving it on the microscope stage.

The only answer to this problem, is to either have perfect eyes,
or to use a microscope where you are looking at a screen, rather
than through a pair of oculars.  This way, your eyes can dart
around, and inspect what they need to see clearly, and the
floaters will be ignored by your brain.

As far as I know, there is only one optical microscope built this
way, and it is the very expensive Mantis.

Because of the great expense of flat screen optical microscopes,
most modern SMD viewing equipment is going to the trivially cheap
method of using a CCD/CMOS color video camera and an LCD screen.

You can do a lot with a cheap USB camera mounted to a boom, a fiber
optic light source, or a ring light, and a laptop computer to
display the image.

-Chuck Harris

Bob Albert via time-nuts wrote:
> What are the important parameters regarding purchase of a stereo microscope?  I
> see some on ebay for around $50; are those good? Bob

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