No. You are wrong. Lines Per Millimeter is objective. It's often read with
the human eye, but can be read by instruments. Lines Per Millimeter can also
be calculated mathematically from the rise from black to white of a single
edge (or fall from white to black). It is identical to the concept of
measuring the resolution of a radar (in this case the measure is degrees).
Generally, the figure is not measured but calculated from the parameters of
the antenna of which gain is the greatest determining factor. The edge of
resolution is where (for example) the light (from white to black) falls off
by 3 dB or half power. It's at this point that two separate objects cannot
be separated mathematically, let alone visually. For photo surveyors and
aircraft/spacecraft spies, this is the ONLY measure that counts. FYI, lpm
for these lenses are not measured by eye but by instruments. Stay tuned for
an installment on how contrast affects this number.

I do err, but not often and not in areas where I have worked.

Regards,
Bob...

From: "Raimo Korhonen" <[EMAIL PROTECTED]>


> Nope - lpm is measured by human eye and it is quite subjective. I think
that MTF is the most objective method, it takes into account both contrast
and sharpness objectively.
> All the best!
> Raimo
> Personal photography homepage at
http://personal.inet.fi/private/raimo.korhonen
>
> L�hett�j�: Bob Blakely <[EMAIL PROTECTED]>
>
> >"Sharpness" and resolution are closely tied together, so I will discuss
them both.
> >
> >Resolution is objective and quantifiable. It is a measure of the ability
to separate two
> >identical objects as they are brought close together. In photography,
this is measured in
> >lines per millimeter where the lines are black the spaces between the
lines are white.
> <snip>
> >Regards,
> >Bob...
-
This message is from the Pentax-Discuss Mail List.  To unsubscribe,
go to http://www.pdml.net and follow the directions. Don't forget to
visit the Pentax Users' Gallery at http://pug.komkon.org .

Reply via email to