Telescopes come in three varieties: ,
, and .
Each kind of telescope collects and focuses light so that
it can be magnified or recorded, but each does so differently.
All perform well when properly designed and manufactured,
but each has its own special advantage. 
Quality is the most important "feature" of binoculars.
In many cases the brand name is a guide to quality. Companies
like Celestron, Leica, Minolta, Nikon, Pentax, Steiner, Swarovski,
and Zeiss have spent decades earning a reputation for high
quality optical products, and they are unlikely to produce
a clearly inferior product. Other companies, like Tasco, Jason,
and Bushnell have built a reputation on low price. 
Microscopes are one of most popular optical instruments for
the hospitals, clinics, biology Labs, and pharmaceutical companies.
Microscopes are available in dozens of specifications and
with a multitude of different features. How to choose a microscope
that best fit your needs? This buyer's guide is intended to
help our customers who need some basic information about microscopes.
Magnification is the degree to which the object being viewed
is enlarged. Magnification, or power, in a spotting scope
is a function of the relationship of two independent optical
systems — the optics of the spotting scope itself and
the eyepiece being used. 
When discussing night vision technology, you need to know
about its technology generations.
... Night vision is made possible by a combination of two approaches:
sufficient spectral range, and sufficient intensity range. 
These have the highest sensitivities and can take the longest
images. Images have to be stacked in a computer to build composite
shots. They can be color, or monochrome. Monochrome versions
are typically higher sensitivity and are often used with LRGB
or UVBRI filters depending on object and camera. They are often/usually
cooled for lower noise. It is in these cameras that the chips
can get really large and quite expensive.