scanning films and negative 35 mm

  • Thread starter Thread starter Tita
  • Start date Start date
T

Tita

Hello,

I need to scan films and negative and then save them on a 300 dpi
resolution and a big size. (A4 format would be perfect). When I scan
the negative on 300 or 720 dpi and rework it on photoshop, I can't
play with the size a lot (well, I can but the quality is not okay).

What would it take to be able to increaze the size dramatically ?
 
Hello,

I need to scan films and negative and then save them on a 300 dpi
resolution and a big size. (A4 format would be perfect). When I scan
the negative on 300 or 720 dpi and rework it on photoshop, I can't
play with the size a lot (well, I can but the quality is not okay).

What would it take to be able to increaze the size dramatically ?
Click to expand...

Go to www.scantips.com and read it carefully. If you scan 35mm film at
300 to 720 ppi, you're not capturing near enough pixels. You need to
be scanning at a much higher resolution, say 2000 to 4000 ppi. It also
sounds as if you're scanning with a flat bed scanner.... you won't get
very good 35 mm scans doing that, for 35mm you really need a real film
scanner.
Charlie Hoffpauir
http://freepages.genealogy.rootsweb.com/~charlieh/
 
Tita said:
Hello,

I need to scan films and negative and then save them on a 300 dpi
resolution and a big size. (A4 format would be perfect). When I scan
the negative on 300 or 720 dpi and rework it on photoshop, I can't
play with the size a lot (well, I can but the quality is not okay).

What would it take to be able to increaze the size dramatically ?
Click to expand...

Some math:
A4 is 210mm x 297 mm convert to inches (210/25.4)=8.27 inches (rounded) X
(297/25.4)=11.69 inches (rounded).

To get 300 dpi for A4 dimensions you need 8.27 inches x 300dpi= 2481 pixels.
for the long side 11.69 x 300 =3507 pixels.
You want the final image size to be 2480 x 3507 pixels. (I dropped the one
pixel)

The ratio of width to height for A4 is 297mm/210mm=1.414:1. (It is the
square root of 2)
The ratio of width to height of 35 mm film (24 mm x 36 mm) is (36/24)=1.5:1.

The aspect ratio is different which means that to fit the 35 mm format to
the A4 format requires some cropping of the 35 mm frame. (The long sides are
too long).

Convert 35 mm frame to inches 24mm/25.4= .945 inches(rounded)
36mm/25.4=1.42 inches(rounded).

Now to get 2480 pixels from a .945 inch wide image you have to scan at
2480/.945=2624 DPI.
So 2624dpi x 1.42inches=3726 pixels for the long side. (you can only scan at
one
dpi). Notice that the long side is more pixels than needed, so you crop. (or
the scanner crops)

So you need to scan at 2624 DPI to exactly fit a A4 printed at 300 DPI.
(the short dimension).

Now I do not know what your scanner has for resolution settings, choose one
that is close but not less than 2624 DPI.

Some scanner drivers give the option of choosing the final DPI and output
size for a particular size document.

If so, choose 300 dpi and A4 at 100%, the scanner should do all the work for
you. Adjust the cropping frame for the area you want to keep.

For the Print size to be correct you may have to set the DPI of the image to
300 DPI in the editor.
The image will most likely have the DPI it was scanned at.
The print size will be correct after setting the DPI of the image to 300.

If you are not good at math, here is a Printing/Scanning Calculator:
http://www.scantips.com/calc.html
 
It is actually very simple.
Never scan 35mm materials at less than 2000 dpi.
Voila.
More is even better!
 
A suggestion: Advise people to scan at 2400 dpi or better to a max of the
dpi at which the increased resolution gives no benefit -- 3000 dpi has been
suggested, as has 4000 dpi, but I leave it to the experts to figure out that
top limit.
 
Some scanner drivers give the option of choosing the final DPI and output
size for a particular size document.

If so, choose 300 dpi and A4 at 100%, the scanner should do all the work for
you. Adjust the cropping frame for the area you want to keep.
Click to expand...

Thanks, it does the trick. I appreciated your long and detailed
explanations.
 
Back
Top