Premium Member Chris Keth Posted November 9, 2004 Premium Member Share Posted November 9, 2004 I was looking around here: Kodak Plus-X Neg. Film and here: Kodak Vision 320T and I was trying to figure out the curves and don't know much about any of them. The only one I know anything about is an exposure characteristic curve (the one that will show you how much over and under middle grey you can expose before detail is lost, that may not be the correct name for it), which I don't even see there. Could someone explain how to read these curves or point me in a direction that could explain it well? Link to comment Share on other sites More sharing options...
Premium Member Greg Gross Posted November 9, 2004 Premium Member Share Posted November 9, 2004 Take a look at 5222/7222 shot in daylight at 1/50. Developer used for this film is Kodak D-96 and normal temp. to develop is 70 degrees which is a rather common temp. for b&w developer, centigrade. Look at Characteristic Curve Graph. As log exposure moves from left to right,density increases sharply or less sharply. For example moving from left to right density increases sharply at time of 12min., compare this to less sharply at 5 min.. Notice the times are color coded for easy indentification. Hope this helps you. You can apply this to just about all the the curve charts except that you'll be dealing in different terms with each one. I think if you study the terminology it will become more clear. Greg Link to comment Share on other sites More sharing options...
Premium Member Chris Keth Posted November 9, 2004 Author Premium Member Share Posted November 9, 2004 Take a look at 5222/7222 shot in daylight at 1/50. Developer used forthis film is Kodak D-96 and normal temp. to develop is 70 degrees which is a rather common temp. for b&w developer, centigrade. Look at Characteristic Curve Graph. As log exposure moves from left to right,density increases sharply or less sharply. For example moving from left to right density increases sharply at time of 12min., compare this to less sharply at 5 min.. Notice the times are color coded for easy indentification. Hope this helps you. You can apply this to just about all the the curve charts except that you'll be dealing in different terms with each one. I think if you study the terminology it will become more clear. Greg <{POST_SNAPBACK}> That's the only graph I actually mostly understand. How does log exposure translate to over/under exposure? Is 0 log exposure equal to normal exposure (averaging to middle grey)? Link to comment Share on other sites More sharing options...
Dan Salzmann Posted November 9, 2004 Share Posted November 9, 2004 That's 70 degrees fahrenheit, isn't it? Link to comment Share on other sites More sharing options...
Premium Member Greg Gross Posted November 9, 2004 Premium Member Share Posted November 9, 2004 Hello Mr. Bunnies, The log exposure is in "Lux" seconds. As you move from left to right the density is subject to change. Assuming film shot in daylight for 1/50. Now I see sometimes that David Mullen ASC usually talks about 1/48 and he knows his stuff. Now I'm not an expert yet as I'm just learning motion pic- ture cameras. A lot of books just say to round it off to 1/50 and not having that experience,I'm going by Kodak chart. The density of your negative will determine the type of print you will obtain. I'm speaking less density or more density. When I shoot still film I shoot with the Zone system. I look at the zones I see in the subject,place my exposure on the Zone which will give me the cre- ative look I want. Maybe I want to place overall emphasis on a white picket fence. Maybe I want it brillant white. I always have a printable negative for my work, a negative with good density for me,the way I want to print. Their are curve charts also for still films,especially sheet film and are often supplied with film. Anyway the density of the negative will determine how your negative prints. All Zones are effected by the density of the negative. I am not familiar with printing from negative to print for movie. Just beginning to study and learn process. For myself I would shoot and talk to the lab. I'm getting a 16mm camera and will be shoot- ing 7222 and I plan on talking with lab until I'm used to film,shooting etc.. Thats a good learning process. Greg Link to comment Share on other sites More sharing options...
Morgan Peline Posted November 9, 2004 Share Posted November 9, 2004 If you get Dave Viera's book: 'Lighting for Film and Electronic Cinematography' out of the library, there's a basic chapter on reading film curves. Morgan Link to comment Share on other sites More sharing options...
Premium Member Chris Keth Posted November 9, 2004 Author Premium Member Share Posted November 9, 2004 If you get Dave Viera's book: 'Lighting for Film and Electronic Cinematography' out of the library, there's a basic chapter on reading film curves. Morgan <{POST_SNAPBACK}> Alright. I've been wanting that book anyway :D Link to comment Share on other sites More sharing options...
Premium Member Chris Keth Posted November 15, 2004 Author Premium Member Share Posted November 15, 2004 Alright. I've been wanting that book anyway :D <{POST_SNAPBACK}> Good lord, I didn't realize that was an $80 book! That'll have to wait a while. Can anyone check out those links and give me a good rundown of how to read the curves in question? Link to comment Share on other sites More sharing options...
Premium Member John Pytlak RIP Posted November 16, 2004 Premium Member Share Posted November 16, 2004 The Kodak website has some good on-line tutorials: http://www.kodak.com/US/en/motion/support/h1/structure.shtml http://www.kodak.com/US/en/motion/support/h1/exposure.shtml Link to comment Share on other sites More sharing options...
Morgan Peline Posted November 16, 2004 Share Posted November 16, 2004 Wow! When I bought it a few years ago it was no way near that expensive! If you go to a film school or university library, I'm sure they'll have it on the shelves - the chapter will only take you 15 minutes to read as it's fairly basic stuff; just well presented. Link to comment Share on other sites More sharing options...
Premium Member Laurent Andrieux Posted November 24, 2004 Premium Member Share Posted November 24, 2004 (edited) Christopher, The curve you're refering to is avaiable for the 320 - I didn't find it for the + X - and is called sensitometric curve. The index is for the equivalent exposure of a 18% grey. The spectral sensitivity curve gives you the sensitivity according to the the light's wavelength, ie its color. The RMS granularity gives you the amount of grain regarding to the esxposure The MTF curves gives you the modulation (ability to render contrast) according to the spatial frequency ie the amount of details (fine details are high spatial frequency) and is the same as modulation transfer. EDIT>The curve named "characteristic" for the + X (I thought I'd find the sensitometric curve, there) shows the densities obtained at different developping time and is then called a gamma/time curve, since the slope of each curve gives you the contrast obtained at this different developping times. You actually could get the same kind of results by increasing temperature instead of time. Greg : David says 1/48 because it's the speed you get when you shoot at 24 fps, like 1/50 is the speed you get at 25 fps. US video is 30 fps, 1/60 s Edited November 24, 2004 by laurent.a Link to comment Share on other sites More sharing options...
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