Martin Preiss
06-29-2008, 03:52 PM
Hey,
this is know how of our school in Prague, and method of establishing exposure (the Spotmeter is Czech invention anyway). (it's similar to Zone System)
So my question is when you look at the pictures. Can you set where are the boundaries of RED on this? Can we implicate them in? Then you will have the exposure range, exact sweet spot and control.
The second pictures are from the Telecine Exposure Calibration Film. Pictures from Kodak 320ASA in IRE and Voltage settings. This should be linked to RED as well, as I didn't find answer where exactly on the RAW image or the sensor the 18% grey card should lie in different channels (RGB). As on this 320ASA film to telecine, the grey patch lies at R39, G39, B36 (IRE) which is 25 25 25 in laboratory timing numbers.
So I'm working on this, but my head is full of production now, so if anybody is here for brainstorming, and know at least basics of exponometry and sensitometry, please share your ideas.
(I know you can always go WYSIWYG. But as cinematographer I always trust my spotmeter, it can't be wrong, I can only misjudge or interpreted wrongly. Skip small chance that there is something with the spotmeter...that's not the point)
EDIT: Oh sorry, on first picture, the numbers from 0 to 1 are the Reflectance of Object if you multiply by 100 you will get it in percentage 0.18*100=18%. The 25% are for normal skin (Caucasian) and 36% for lighter skin. Then there is the base line of EV Exposition Value, where this reflectance is falling when exposed. And above that there is the media ratio 1:100 is 6 2/3 of stops. 1:128 is 7 stops...
EDIT2: And as everything on film this is logaritmic..even the EV are linear
this is know how of our school in Prague, and method of establishing exposure (the Spotmeter is Czech invention anyway). (it's similar to Zone System)
So my question is when you look at the pictures. Can you set where are the boundaries of RED on this? Can we implicate them in? Then you will have the exposure range, exact sweet spot and control.
The second pictures are from the Telecine Exposure Calibration Film. Pictures from Kodak 320ASA in IRE and Voltage settings. This should be linked to RED as well, as I didn't find answer where exactly on the RAW image or the sensor the 18% grey card should lie in different channels (RGB). As on this 320ASA film to telecine, the grey patch lies at R39, G39, B36 (IRE) which is 25 25 25 in laboratory timing numbers.
So I'm working on this, but my head is full of production now, so if anybody is here for brainstorming, and know at least basics of exponometry and sensitometry, please share your ideas.
(I know you can always go WYSIWYG. But as cinematographer I always trust my spotmeter, it can't be wrong, I can only misjudge or interpreted wrongly. Skip small chance that there is something with the spotmeter...that's not the point)
EDIT: Oh sorry, on first picture, the numbers from 0 to 1 are the Reflectance of Object if you multiply by 100 you will get it in percentage 0.18*100=18%. The 25% are for normal skin (Caucasian) and 36% for lighter skin. Then there is the base line of EV Exposition Value, where this reflectance is falling when exposed. And above that there is the media ratio 1:100 is 6 2/3 of stops. 1:128 is 7 stops...
EDIT2: And as everything on film this is logaritmic..even the EV are linear