Quote Originally Posted by Photo Engineer View Post
So, how did you measure it?

PE
Hello Ron,

we've used the industry standard method, which is used for decades (e.g. by all lens manufacturers like Zeiss, Leica, Schneider etc.) for analysing system resolution (film + lens).
The resolution charts were analysed under a microscope with 40x and 100x enlargement. Under a microscope you really see what the film has captured. It's the most precise method. Usable for negative film and positve film, BW and colour.
We've discussed our methods and results with Dr. H. Nasse, chief optic designer of Zeiss, and got confirmation.

Furthermore we analysed the whole imaging chain: Optical enlarging with APO-lenses, scanning with drum scanners (Imacon X5 and ICG 370) and Nikon Coolscan 5000 scanner, and projection with different high quality projecting lenses.
Very short summary of the results:
Highest system resolution in the whole imaging chain is achieved with optical enlarging and projection. Loss in resolution compared to the results under the microscope in only 5 - 10%.
Same with slide projection. Getting 120 lp/mm on the projection screen with e.g Velvia 100 is possible with high quality projection lens
[the current digital beamers (the most expensive 7000 - 10000 class) with their extremely low resolution of max. 2 MP deliver 15 - 20 lp/mm on the screen.
Slide projection is the field where quality advantages of film compared to digital technique is really huge].
With drum scanners the reduction in resolution is bigger, 20 - 40% dependent on the film.
Far behind is 4000 ppi scanning with the Coolscan 5000 (effective 3600 ppi). Worst resolution values of all, significant loss in detail. 70 lp/mm is the limit, more is not possible, even with high resolution films or higher object contrast.
Scanners are limited by the Nyquist frequency. An optical imaging chain (lenses + film) is not, here the limiting factors are diffraction and object contrast.
As resolution is dependant on object contrast, the differences are bigger with higher object contrast (more than our 1:4), and they decrease with less object contrast.

Best regards,
Henning