Film Scanning in 4K UHD
Posted on the 24th March 2018
I decided to write the article as there seems to be some general confusion over the expected resolution of film. These days we are used to counting in lines of resolution and pixel numbers, here we will look at both TV resolution and film resolution to help compare them and see what we might expect out of a film to digital transfer.
There are 3 things that determine film resolution and quality,
1. Film type and speed
2. Film cell size (16mm, 8mm etc.)
3. Optics used in the film camera
Remember first that film doesn’t have pixels rather film is made out silver halide and thus has a grain structure, this grain size varies depending on the type of film, fast films around 200 to 500 ISO have coarser grain and slower films around 50 ISO have a finer grain structure so can generally resolve more lines of resolution.
Optics also play a part, a good lens will resolve more information and be less prone to imaging issues that can degrade the image on the film.
It goes without saying then that the size of film will determine how much resolution it will likely have from the tiny 8mm cell right up to the glorious 70 mm of IMAX, but remember when working with older films resolution can vary, here are the sorts of resolutions we can achieve with good stock,
3.5K = 35MM
1.8K = S16MM
1.5K = 16MM
800 = S8MM
500 = 8MM
So is it worth scanning films up to 16mm in 4K?
Yes and no it depends on what the intention is, if you are going to just work in HD and have the films pillar boxed (that’s back bars either side) then an HD scan is more than sufficient especially for 8mm and Super 8, higher scan resolution can help when a picture is going to be cropped such as for use to fill a 16:9 widescreen from a near 4:3 original. This gives the editor the option to zoom and crop (Pan and Scan) without effecting the image quality as it will not be enlarged. So in this instance 2.5K to 4K is a suitable use of higher resolutions.
It also means if required for archival purposes we can scan the entire cell including the sprockets and film edges so no part of the image is cropped.
Having great dynamic range and colour will help too as its sometime more the perception of quality rather than the numbers that make images look good.
Posted in Transfers[ssba]