Archived posting to the Leica Users Group, 2000/10/30
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]on 30/10/00 7:16 pm, Austin Franklin at austin@darkroom.com wrote: > Erwin, I don't know if you're aware of this, but you will never just 'line > up' your digital sensors pixels with your target. Say you are shooting > 1:1, and you are trying to record a line that is .001". You would need to > sample at at least twice that frequency, or .0005" to pick that up, since > it could fall exactly between two sensors, and not get picked up by either > one. > > So, when you calculate the resolution you need for a digital sensor to > record information, don't forget to multiply by (at least) 2x the target > size you want to resolve to. > > I also believe line pairs, are exactly that, line pairs. So, 40lp/mm would > be 80lines/mm or 2032 lines/inch but in order to pick them up, multiply by > 2, and you get 4064.... Imagine that ;-) That was what I mean by glaringly obvious but I knew Austin would be better at expressing it than me. Erwin's position refers a lot to 'widely accepted' and 'consensus' points of view but these are consensuses amongst -- guess who -- CCD manufacturers. Hmmm. Wonder what their angle could be? They don't represent anything like a consensus position amongst the very large community of digital/silver users who would regard a 20Mb color file as hopelessly unacceptable. If anyone doubts this do a poll on the digital silver list. - -- Johnny Deadman http://www.pinkheadedbug.com