I was reading some previous comments on how film is still sharper then digital on some films, and how the Nyquist theory works into keeping digital from being better. This is for the same size of sensor/film. I was looking at some images of a landscape and it showed more definition in the trees, while the digital image was softer in that area. Same lens. I don't know how the Nyquist theory mixes into all this. Some films have around 100 or more lp/mm, especially B&W. Yet we see some digital sensors challenging medium format. And the digital image is cleaner without grain getting in the way.
So what is the actual truth on all this, or is there any conclusion?
That’s a loaded question if I ever saw one.
You’re always going to have people say the film will always have more resolution/sharpness/whatever.
I’d propose a couple of measurement criteria:
Resolution is the number of line pairs per mm rendered above 50% contrast ratio. Commonly referred to as spatial resolution.
Sharpness is the amount of contrast there is between the dark and light parts of the edges in the image.
You do have to have a minimum amount of resolution to render a certain level of sharpness. You can’t have contrast between a dark and light part if there’s no spatial resolution to render a dark and light part.
Digital sensors tend to have a contrast response of 100% all the way up to the physical spatial resolution limit of the sensor, whereas film rolls contrast off as spatial resolution is added. This means that film by the measurements defined above tends to leave a lot of “meat on the bone” in the resolution and sharpness departments, whereas digital is what you see is all you’ll get. There’s no more resolution or hidden detail to pull out because the contrast response is always well above the 50% mark.
Why 50% contrast? Even though we have instrumentation that can measure that resolution below 50% contrast our eyes are actually relatively insensitive to less contrast than that, so that’s resolution we tend not to see. It can be brought out with either a developer that “punches up” the image, or assuming you scanned it in with enough spatial resolution, can be brought out with sharpening. When you sharpen as image, all you’re doing is adding contrast along edges. You can tunes that to add contrast down in the low contrast response areas, thereby significantly boosting perceived resolution and sharpness.
As
@MattKing said, they’re interdependent, but also pretty inter-related.