Archived posting to the Leica Users Group, 2000/11/17
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]>>In a coal mine at midnight with one candle off in another part of the cave you >>have only 5 units of light to work with. >>You don't want to loose one. >>Could that be true? Seems like it would be. >>mark rabiner >>:) >>http://spokenword.to/rabiner/ > >That's it exactly, Mark. It only matters when you are measuring darkness, >not light! > >Tina Hi All, My original question to Tina was: "a UV filter cuts light?? OK, some, but can you measure it?" I did not ask about vignetting (a quite different issue), or whether Mark spends his midnights down coal mines, but does it make a discernible difference to the exposure? Tina says it does, and I respect her subjective experience, but I wanted to know what *measurable* difference there is, if any. Mark's logic sounds fine but skates around the question. 1 in 5 is 20% and no one wants to lose 20%! But who says a UV filter cuts 20%, Mark? That's neutral density filter territory. No matter what the absolute light level (beach or coal mine), the question was what *proportion* of it does a UV filter cut? And is it significant? An aside to Tina: What instrument do you use to measure darkness? ;-) Nick.