How may pixels needed to approximate 35mm film?

Archived from groups: rec.photo.digital.slr-systems (More info?)

People tend to quote some fairly outrageous figures when talking about
the effective resolution of film. However from my experience I've found
that typical 100 ISO print film is lucky to produce the detail of a 4MP
image. When I used to use film, I'd generally get it scanned on a
Frontier and put on CD at a resolution of 1840x1232, and at that size
the grain was usually very noticeable. The catch is that film grain
looks much nicer than digital noise, so it matters less.

It varies a huge amount for different types of film though. My favourite
print film used to be Kodak Ektar 25 ISO. It had about the finest grain
I've ever seen. Unfortunately they stopped producing that probably
around 10 years ago.

Anyway having just recently started using a 20D I'm now confident that
an 8.2MP digital convincingly beats film for pure resolution,
particularly at high ISO settings. My 20D at 3200 ISO produces smoother
images than most of the 400 speed films I've used. At 3200 film becomes
more grain than image.

> I know theres probably lots of factors here, and it's probably one of those
> 'how long is a piece of string' questions. But as a ball park figure, does
> anyone know how many pixels you need to equal the resolution of 35mm film
> especially in regard to the enlargements?
>
>
>

Archived from groups: rec.photo.digital.slr-systems (More info?)

"Steve Franklin" <honkey@lips.com> writes:

> I know theres probably lots of factors here, and it's probably one of those
> 'how long is a piece of string' questions. But as a ball park figure, does
> anyone know how many pixels you need to equal the resolution of 35mm film
> especially in regard to the enlargements?

No, not again!

You will get lots of answers to this, ranging from about 6MP to 50MP
or more. It's *really* hard to give a figure that means anything, as
the two media have different capabilities and limitations. For
example, some prefer the relatively noiseless look of large digital
enlargements, while others believe there is more detail in a grainier
film enlargement. And some judge by the theoretical resolution limit,
others by looking at images. And some insist that digital scanning
entails major sacrifices in resolution from film.

My feeling is that the crossover is somewhere in the 8-10MP range; my
impression is that the bigger sizes (13.9MP from the Kodaks, 11 or
16MP from the Canon 1D series) can, in the right circumstances, beat
35mm film in usable resolution and rival larger formats.

--
-Stephen H. Westin
Any information or opinions in this message are mine: they do not
represent the position of Cornell University or any of its sponsors.

Archived from groups: rec.photo.digital.slr-systems (More info?)

According to Steve Franklin <honkey@lips.com>:
> I know theres probably lots of factors here, and it's probably one of those
> 'how long is a piece of string' questions. But as a ball park figure, does
> anyone know how many pixels you need to equal the resolution of 35mm film
> especially in regard to the enlargements?

Well ... I've got an older Nikon slide/negative scanner -- from
before the "Cool" name came out on such scanners -- and it was *not*
cool in operation. It is high resolution, but *very* slow -- especially
on a windows 3.1 system, which is what I had when using it.

The scanner would scan to either ".BMP" or ".TGA" format -- both
with no compression, and at a full-resolution scan, would produce 72MB
images, which is 24 MP.

Zooming into images scanned from ASA-64 (I did say this was
old?) I got images where the grain was obvious before the pixel size
became obvious. A slower, finer-grain film might have been able to make
use of all 24 MP, but it was not really needed for the Ektachrome.

I hope that this helps,
DoN.

--
Email: <dnichols@d-and-d.com> | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

Archived from groups: rec.photo.digital.slr-systems (More info?)

On Wed, 28 Sep 2005 13:52:16 GMT, "Norm Dresner" <ndrez@att.net>
wrote:

>>I've gotten really fine reproduction at 8x10 with a ~6 MP camera, but
>wouldn't want to take it much bigger than 11x14 for most subjects.

Indeed, my old D60 has been the source of a ton of A3 prints, in the
last three years, and my new 20d's 24MB files yield great 13X19-inch
images.

Actually, today's digital image hobbyist can easily surpass the
results of the average home dark room of ten years ago and do it much
cheaper.

>In the final analysis, nothing beats the "snap" of a projected Kodachrome
>slide for wowing the audience, but that's a whole different mode of
>presentation.
> Norm

You might look at projected images from a QXGA (2048X1536) or even an
SXGA (1400X1050) projector before you start talking about "snap". They
are expensive but have gone down from $20K to $10K in less than two
years. In five years those projectors will be in the $2K range for
home theater.

Also keep in mind that a decent lab can produce slides from digital
files the equal to any from film and have just as much contrast and
brightness as you want.

Dave
East Englewood
------------------------
The proof is in the print.

Archived from groups: rec.photo.digital.slr-systems (More info?)

William Oertell wrote:
> I don't know...18MP works out to 144 lines per mm, and I don't think
> there's any 200 ISO film that even comes close to that.

144 lines per mm works out at 72 line *pairs* per mm, which is what
film resolution is measured in.

Most (all?) ISO 200 films can handle this. Most go beyond 100 lppmm,
which would work out at ~34MP. (if you assume that 1 line pair = 2
rows of pixels).

However, grain (although not directly linked to resolution) is a major
factor in the overall perception of quality. Digital cameras make more
*efficient* use of pixels than scanned film, so viewers perception
often favours the digital image, even though it has less "information"
in it.

-John

Archived from groups: rec.photo.digital.slr-systems (More info?)

Steve Franklin wrote:

> I know theres probably lots of factors here, and it's probably one of those
> 'how long is a piece of string' questions. But as a ball park figure, does
> anyone know how many pixels you need to equal the resolution of 35mm film
> especially in regard to the enlargements?

And ...

It will depend on how large a print you're looking to make.

Archived from groups: rec.photo.digital.slr-systems (More info?)

<dave6134@verizon.net> wrote in message
newsivmj1pacf2nsot7a7mshbjchn2rapin5a@4ax.com...
> On Wed, 28 Sep 2005 13:52:16 GMT, "Norm Dresner" <ndrez@att.net>
> wrote:
>
> >>I've gotten really fine reproduction at 8x10 with a ~6 MP camera, but
> >wouldn't want to take it much bigger than 11x14 for most subjects.
>
> Indeed, my old D60 has been the source of a ton of A3 prints, in the
> last three years, and my new 20d's 24MB files yield great 13X19-inch
> images.
>
> Actually, today's digital image hobbyist can easily surpass the
> results of the average home dark room of ten years ago and do it much
> cheaper.
>
> >In the final analysis, nothing beats the "snap" of a projected Kodachrome
> >slide for wowing the audience, but that's a whole different mode of
> >presentation.
> > Norm
>
> You might look at projected images from a QXGA (2048X1536) or even an
> SXGA (1400X1050) projector before you start talking about "snap". They
> are expensive but have gone down from $20K to $10K in less than two
> years. In five years those projectors will be in the $2K range for
> home theater.
>
> Also keep in mind that a decent lab can produce slides from digital
> files the equal to any from film and have just as much contrast and
> brightness as you want.

You're dreaming.

--
Regards,
Matt Clara
www.mattclara.com

Archived from groups: rec.photo.digital.slr-systems (More info?)

It comes to 144 lines per mm.
(No it comes to 144 pixels per mm).

But resolution for film is expressed in line pairs per mm.
144 pixels per mm can resolve about 100 lines per mm.
This is about 50 line pairs per mm.
------------------+++++------------------
(This is depending on the direction the measurement
is taken, because of the bayer pattern, it is direction
dependend, but 144 pixels in both directions can resolve
about 50 line pairs in any direction.).

How does this work. You need more than one pixel to
resolve a line. If the lines fall exactly on the pixels they
would be able to resolve a line for each pixel. But if the
lines fall exactly between the pixels you would only get
half lighted pixels which will result in a gray image.
So you need about 1.5 pixel for each line.
(Depening on the direction).

But you can turn the question around, how much 35 mm
film would you need to store say 9 Mb on (3Mp image
without compression).

ben brugman


"William Oertell" <oertell_NOT@pacbell.net> schreef in bericht news:11jmti14u4r04e@news.supernews.com...
> I don't know...18MP works out to 144 lines per mm, and I don't think
> there's any 200 ISO film that even comes close to that.
>
>