Newbie: Negative Scanning Questions

I was interested in making digital prints from some of my old 35mm
negatives and am seeking some scanning advice. My experience with digital
photography so far has only been with making low resolution scans of negatives
for webpages. My equipment is Adobe Photoshop, a HP ScanJet 4570c with
negative adapter (yes I realize it's not a true negative scanner like the
better Nikon's and Minolta's) and a Cannon i470D bubblejet printer. I simply
want to make the best occasional family prints I can with this hardware &
software in printing 4x6, 5x7, and 8x10 photos.
The scanner is capable of 2400 dpi and the resolution of the printer is 600x600
in black and 4800x1200 in color.
1) My first question involves the scanning format...should I save the
scan as a TIF, compressed TIF, JPEG or GIF? Perhaps I should save it (archive
it) as a TIF and do the editing of it and saving it as a JPEG to print? (print
the edited JPEG)
2) My second question involves the resolution setting of the scanner.
Keeping in mind that I will be doing 4x6, 5x7, and 8x10 and given that the
maximum resolution of the printer is 4800 x 1200dpi, should I scan the 35mm
negatives at the full 2400 or is that going too far? The size of the file
isn't really a concern if I can get higher quality prints using the high
scanner resolution. But, if it the resulting print at 8x10 will look exactly
the same with a smaller scanner resolution, then I'd prefer to use the smaller
setting to reduce computer processing time and space.
Any thoughts to the above questions are appreciated. Thanks.

 

Good questions!

1. If you're using Photoshop, you should be able to scan in the negative
directly to PS. From there you can save as a PS file, TIF, JPEG (suggest
saving as a PS file)

2. You may be only able to scan the neg's at 600 dpi max. 300 dpi should
do fine. Having done the same recently (I'm using an Epson 1650 with their
slide/negative adapter), the max that I could scan at is 600. Make sure
that the neg's are clean.

Best wishes

 

300 DPI should be fine for scanning a negative? Maybe if the final result
is to be used to produce a postage stamp (assuming the negative is 35mm).
If you're going to scan a negative at 300 or 600, you may as well scan the
print at 400, since you'll get much better results. The 1650 can scan at
1600 and I've scanned negatives and slides at that resolution (you can go to
interpolated 3200, but the optical resolution is 1600). You're not going to
beat a film scanned for quality of output, but it does a reasonable job.

Zyg

 

Wait! What are you talking about? The poor poster is certainly confused by now.

Let's make this simple. The poster wants a rule of thumb. And let's talk
about pixels per inch, and for the sake of simplicity use "dpi" as meaning
pixels-per-inch. (Now don't you prepress people jump all over me! We are
making something for the amateur home scanner who justs wants to make a
print!)

Short answer to the poster: for your 35mm film, use 2000dpi for 8x10,
1400dpi for 5x7. That's _without using the scaling_ option of your
scanning software.

(Note that it is highly unlikely that your flatbed scanner really does
2000dpi, but for the sake of simplicity - just go for it.)

Here's why. First, you want reasonable border on your prints; 35mm film
does not scale into 8x10 and 5x7 evenly so your prints must 'float' and
therefore will be smaller (typically 6"x9" for 8x10 and 4.5"x6.8" for
5x7).

For each final print size (6"x9" for example) you want 300dpi _at that
print size_. So you scan your original negative (2.4cm x 3.6cm) as high as
neccessary to achieve 300dpi at the final print size.

(And someday, just friggin SOMEDAY we will stop using the term "dpi" for
scanning and will use SPI and also convert this whole print PPI and "DPI"
to some rational scheme. But that's entering into confusion again.)

 

smaller


2400 dpi is NOT going too far to print 8x10 inches from 35 mm film.
It is the requirement in your case.

There are three rules of thumb to keep in mind.

1. On ink jet printers, you want to print in the 240 to 300 dpi range. The
4800x1200 dpi rating of the printer is about ink dots, and is like a quality
factor - it is NOT about images. Ink dots are NOT pixels, very different
concepts. You would select one of the printers better quality modes for photo
quality, but this is not about the image itself.

The image itself should be scaled to print in the range of 240 to 300 dpi,
which refers to image pixels.

2. if you will print 8x10 inches at say 300 dpi, then this requires an image
size of:
(8 inches x 300 dpi) x (10 inches x 300 dpi) = 2400x3000 pixels.

You can plug any desired numbers into this formula, but you can see that if
you have less than 2400x3000 pixels, then you have too few to space them over
8x10 inches at 300 dpi. But you dont necessarily need 300 dpi, 240 dpi will be
nice too.

3. As an aid to determine scanning requirements quickly, the ratio of
(scanning resolution / printing resolution) is the enlargement factor.

We always want to print in the 240 to 300 dpi range, so the meaning is (for
example) that if we want to print a 4x enlargment at 300 dpi, then we should
scan at 300 x 4 = 1200 dpi. Plug in any numbers.

But if you are scanning 35 mm film (24x36 mm size, or roughly 0.9 x 1.4
inches), then this is very small, and it needs much enlargement to print 8x10
inches. 8x12 inches is about 9x enlargement of full frame 35 mm film (film
size to print size). If for example, you scan at 2700 dpi, and print at 300
dpi, then this gives 2700 / 300 = 9x enlargment, and it prints 8x12 inches.

If you have a 2400 dpi scanner, then 2400 dpi cannot enlarge enough to print
8x10 at 300 dpi (from 35 mm film), but you can print the same 9x size at
2400/9x = 267 dpi which should be satisfactory (see 1. above).

 

If you archive in TIF, why should you convert to JPG for printing?

Don't confuse your printers positioning capability for single color
ink drops - the DPI values given - with the actual PPI (full color
pixel per inch) it can achieve. This value is almost never given by
printer manufacturers because even the best inkjet printers are in the
300 to 450ppi range on the most expensive paper they use.

For a perfect photo you need about 300ppi - on 8x10 this would mean
2400x3000 pixels.

If you scan negatives with a flatbed scanner you will find that
scanning at the specification limits gives a clear image of marketing
vs. technical department of your scanner manufacturer.

But as we have seen before 2400ppi scanning is the minimum for the
8x10 print.

For more details take a visit to Wayne's website...

Michael