The point of shooting a target is to make sure the scanner is in focus. An out-of-focus scanner will do a good job at hiding the aliased grain. Also, I'm not talking about truly underexposing the film. Exposing white paper at 2 1/3rd stops under what an incident light meter would say to expose at is the same exposure as a gray card exposed normally. Another option (that would yield the same exposure) is to use a spot meter on the white paper and expose normally. This will yield the same number of photons reaching the film as spot metering on a gray card. --Bob > -----Original Message----- > From: Roman Kielich® [SMTP:[EMAIL PROTECTED]] > Sent: Thursday, September 21, 2000 6:55 AM > To: [EMAIL PROTECTED] > Subject: Re: Nikon Apparent Grain (was Re: Nikon > LS-30/Vuescanquestions) > > At 11:24 21/09/2000 +1000, you wrote: > >Murphy, Bob H <[EMAIL PROTECTED]> wrote: > > > Why won't a piece of white paper under exposed by 2-1/3rd stops > produce > >the > > > same exposure as an 18% gray card? > > > >Because a grey card photographed with a 28mm lens at 2 metres won't be > full > >frame? The main thing I'm concerned about is differences in grain due to > >underexposure. Perhaps some of the more experienced photographers > >on the list could comment, but I would feel more confident comparing > grain > >effects in "correctly" exposed negs/slides than in film exposed outside > its > >latitude. > > > >Rob > > All modern films have a multilayer construction, each R, G, B - sensitive > layer consists of 2 or 3 layers of different speed (grain size). The > bigger > the grain, the bigger the speed. If you underexpose a film, you record an > image in more sensitive layer, which is grainier. That construction allows > > for a bigger exposure latitude. > why do you need 28 mm lens at 2 m distance to measure/assess the grain? > the > image doesn't have to be sharp to determine grain size. According to a > standard, the grain is measured on an uniform gray (D=1.0) using an > aperture of 48 microns. According to Fuji- > diffuse rms granularity of Velvia RVP is 9, Provia RDPII 10, Sensia II > (RA) > 10, Astia RAP 10, Fujichrome MS at EI 100 10, EI 200 11, EI 400 13, EI 800 > > 15, EI 1000 16, Provia 400 RPH and Sensia RH 15, Sensia 200 RM 15, > Fujichrom prof 64T 11, Fujicolor NPS 160, NPL 160, NPH, Superia Reala CS , > > Superia CN, Superia 200 CA, Superia 400 CH - all have rms granularity of 4 > > > ==================================================================== > The filmscanners mailing list is hosted by http://www.halftone.co.uk > To resign, <mailto:[EMAIL PROTECTED]> with UNSUBSCRIBE > FILMSCANNERS in the title, or UNSUBSCRIBE FILMSCANNERS_DIGEST if you are > reading the Digest. ==================================================================== The filmscanners mailing list is hosted by http://www.halftone.co.uk To resign, <mailto:[EMAIL PROTECTED]> with UNSUBSCRIBE FILMSCANNERS in the title, or UNSUBSCRIBE FILMSCANNERS_DIGEST if you are reading the Digest.
