No - I am not wrong - when it is done the way you say, it is effectively MTF. There is no absolute black or white in the nature, or in the world if you will. All the best! Raimo Personal photography homepage at http://personal.inet.fi/private/raimo.korhonen
-----Alkuper�inen viesti----- L�hett�j�: Bob Blakely <[EMAIL PROTECTED]> Vastaanottaja: [EMAIL PROTECTED] <[EMAIL PROTECTED]> P�iv�: 16. tammikuuta 2002 19:33 Aihe: Re: And did I mention wrong >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 .
