35mm digital equivalent site:
the slide / negative
The 35mm negative / slide
Digital terms using 35mm as your base: What is the equivalent of 35mm color
slide film in digital? Where do those pixels come from?
mega pixel camera can produce equivalent of a 35mm film? What mega pixel
camera enlarges as well as a 35mm color film?
USING A 2700 DPI NIKON COOLSCAN SLIDE/COLOR NEGATIVE SCANNER:
us work backwards using a Nikon coolscan LS-10 slide scanner that scans around
dpi from a 35mm slide film measuring 24mm x 36mm (.94 x 1.42 inches).
A 2700 dpi or ppi (pixels Per inch) produces 2700 X 1.42 = 3834 pixels from the width of a slide film (1.42 = 36mm) and it produces 2700 X .94 = 2538 pixels from its height.
Now letís multiply 3834 BY 2538 (3834 x 2538 = 9,730,692 OR approximately 10,000,000 which is 10 mega pixels. This means the entire surface of the 35mm film will produce about 10,000,000 pixels or it takes 10,000,000 pixels to reconstruct the image accurately in the digital world.
each COLOR pixel is represented by 3 primary colors (Red, Green, and Blue),
then by multiplying 10,000,000 by 3 we get about 30,0000,000 characters or 30
Mega Bytes. This is the amount of storage needed to keep track of the color
info for the image (each pixel has a 3 character overhead to remember its
color/density attributes). Therefore it takes a 30 mega byte uncompressed TIFF
(.tif) file to
accommodate one scanned 35mm slide film @ 2700 dpi.
you have a black and white negative (grayscale/No color), then the size of the
file will only be 10,000,000 (10 mega bytes) since the density of each
grayscale pixel is represented by only ONE informational byte or character.
Now letís move forward and see why 2700 dpi was chosen to scan a 35mm negative.
Letís assume that a typical 100ISO slide film (measuring 24mm X 36mm) has a resolution of about 107 lines/mm.
Please note that this number could be more (up to 120) or less (say 80) for this type of film. A resolution of 100 to 110 lines/mm is typical. This number can be found in the technical specifications for a slide film from a manufacturer like Kodak.
Let's draw 107 lines, alternating between black and white as shown below:
Please note that each of the above two squares are 1mm in height (and in width of course!)
let's pick out 1 sq mm of our 35mm film (in red) and put these squares on top
of one another (transpose them).
means the entire film produces (24X107) x (36X107) = 9.9 million Pixels.
Please note that it takes about 21 floppies to accommodate this image or one 700MB CD to accommodate about 23 of these images. By the same reasoning, a 4.7GB DVD Rom can accommodate about 156 of these images.
What digital camera will give you this many pixels?
A 6 mega pixel D Slr with an aspect ratio of 2/3 produces 3000 X 2000 = 6,000,000 pixel image.
An 8 mega Pixel D-Slr camera with an aspect ratio of 2/3 will produce 3464 X 2310 = 8,000,000 pixel image.
A 35mm slide film with an aspect ratio of 2/3, scanned at 2700 dpi produces (1.42 X 2700 = 3834) by (o.94 X 2700 = 2538) or 3834 X 2538 = 9,730,692 or 10,000,000(approx)
What happens if one scans a 35mm slide film with the above specifications at 5400 dpi/ppi?
Not much. The scanner will enlarge the pixels (creates fake pixels) using a process called interpolation. It WILL NOT enhance the quality of the scan. A practical example of this is if you have 2700 dollars and the car you want to buy costs $5400 and you simply can double your wealth using a mirror in front of the original $2700! True, you will see $5400 but the image you see in the mirror is just an image and has no real value.
24 X 36 X 11574
= 10,000,000 = 10 MegaPixels
is pixels/sq. mm.