Thanks Iliah. Admittedly I know nothing about film recorders, so my concept of what you did 'outputting 5000 patches onto film directly' is very limited! I don't understand how it's not essential to have Dmin & Dmax mapped to black & white when shooting a target on film. When building a 'scanner' profile (not a 'camera' profile), 0,0,0 & 255,255,255 (on an 8-bit scale) are literally mapped to the darkest and lightest patches when I use LPROF to build a profile for my Velvia film using Wolf Faust's 35mm targets (288 patches, IT8 chart). Are you not building a 'scanner' profile? I know for 'camera' profiles profiling packages don't require the black on the chart to be 0,0,0 from your camera & white to be 255,255,255 (in fact, that's really hard to do since typically your camera has a much wider dynamic range than that possible from imaging a reflective target)... because all it's doing is building a 3x3 matrix, no? For that matter, how does Wolf Faust even create the IT8 targets on positive film? The black on the grayscale ramp is pretty much Dmax & the white is Dmin... perhaps I should ask him, but let me know if you know :) Many thanks! Rishi On Wed, Feb 23, 2011 at 3:21 PM, Iliah Borg <ib@xxxxxxxxxxx> wrote: > Dear Rishi, > > On Feb 23, 2011, at 5:43 PM, Rishi Sanyal wrote: > >> Iliah, >> >> You mention: "Argyll makes excellent profiles for colour negative >> films, something no other profiler can do (export DNG from vuescan and >> bring it to RPP - and you will see)" >> >> Do you have color targets shot on negative film (I think Fuji used to >> once offer a negative film target) or do you shoot targets yourself on >> film? > > For daily outdoors use I shoot ColorChecker Passport - it is good enough to > put the colour response into the ballpark. In the studio I prefer > ColorChecker DC. For film simulation profiles I used a recorder to output the > targets (about 5000 patches) onto the film, directly. Those are, of course, > film simulations and very generic, measured right from the film - while for > normal use one wants to scan and make film+scanner profiles. Some of the > simulation profiles done with Argyll are incorporated into RPP. > > >> If the latter, ideally you'd want the blackest black & the >> whitest white on the grayscale gradient to map to the lowest exposure >> (clear film for a developed negative) & highest exposure (Dmax for >> developed negative) possible on the film, correct? > > Actually this is not essential for negative profiling. Most important as far > as my experience goes is to get 18% grey to be exposed and developed > sensitometrically correct. That is to expose using a spotmeter as an > indicator, bracketing +/-2 stops with half a stop difference. Now, if you > want very wide target all you need is to make a composite of 3 exposures, > centre, +2, and -2. Such a target covers the dynamic range of the best > negative film I ever encountered. > > -- > Iliah Borg > ib@xxxxxxxxxxx > > > > >