a question for mr. Pytlak

[Filip Plesha]

I was just wondering how come Kodak does not specify the maximum resolving power for their films as they used to for older films (for both 1.6:1 and 1000:1 contrast). Fuji usually does that for their still films, and Kodak did it for older emulsions.

 

Anyway, do you have any data on the maximum resolving power of today's film stocks? I mean, where the MTF curve ends on the graph. Those graphs usually end at 80 or 100 or something like that, so you can't really see the maximum resolving power. What I am currious about is the max resolving power of films such as the new 5212, and 5248. And perhaps one of the slower films.

 

It is good to have some real arguments in discussions, all I have is my speculation based on my prediction where the curve is going to end.

 

By the way, the curve for the 5248 goes all the way to 200lp/mm? Is this data accurate? I find it rare that a color negative of ISO 100 speed reaches that kind of resolution. For example, the still negative film portra 100t reaches some 150 lp/mm as I recall. This should be newer technology (probably vision generation)

than EXR, so how come it shows such results?

[John Pytlak RIP]

Resolving power is a good measure of sharpness for text and other high contrast material, but continuous tone image sharpness is best measured by Modulation Transfer Function (MTF). I personally usually use 10% modulation as a guide to how much fine image detail is actually usable on the film, but the correct way is to cascade the MTF function of the system, and calculate an area under the curve weighted by the visual acutance of the human eye at the expected image magnification. (See published technical papers by Kodak's C. Nelson, R. Lamberts, C. Crane, R. Morton, and others).

 

Thanks for drawing my attention to the MTF curve for 5248. It appears they accidently used the wrong color codes for the curves -- normally the blue (top layer) is sharpest, the green is next, and the red (bottom imaging layer) is least sharp.

[Filip Plesha]

Yes, the green and the red have been mixed up...

 

I suspect that you use 10% because everything lower than that would be "consumed" by grain. Right?

 

By the way, is the curve accurate ? Does it really go beyond 200 lp/mm?

Or is there another mixup with the numbers?

[John Pytlak RIP]

It agrees with the originally published data sheet, so it was based on the data generated when the film was originally designed over ten years ago.