Re: Buying an Eyepiece

On Dec 19, 1:17 pm, Richard J Kinch <ki...@xxxxxxxxxxx> wrote:
Neil B. writes:
The "magnification" of a simple magnifier is
conventionally stated as the apparent enlargement when your eyeball
is 10 inches (254mm) away from the object, this being the
conventional

I think it is now "250mm" in lack of deference to the English system -
?.

It never was 250mm, although it is often misstated as such.

But the eyepiece does
provide more information, because you couldn't see all the detail with
a "1x" eyepiece, or looking at the best direct projection image
available - our eyes aren't good enough.

Enlarging an image does not add information, it can only take it away,
like an electrical transformer and power.  The purpose is to match
resolving characteristics.  One of several characteristics that make
eyepieces and objectives incomparable.  Or think of a photographic
negative and enlarging prints.  The print can vary the magnification,
but it will never add any information to the image, that is once and
forever fixed when the photograph is recorded on film.  The camera lens
and the enlarger lens both have a magnification, but they are not
comparable.

Or to put it simply NA is the only number that is meaningful. The
rest are interesting, maybe, but NA is the only number that counts.

Kevin Cunningham
SMS
.

Relevant Pages

  • Re: Buying an Eyepiece
    ... Enlarging an image does not add information, it can only take it away, ... negative and enlarging prints. ... The camera lens ... and the enlarger lens both have a magnification, ...
    (sci.techniques.microscopy)
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    ... We will call this Zero Magnification. ... The process of enlarging the size of something, ...
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