8 Aug
2005
8 Aug
'05
11:53 a.m.
Re: "I reckon that a good 35mm camera (good meaning a top-end lens and
fine grain film) is equivalent to 12-20 megapixels."
My understanding from the camera companies, which I've heard more than once
(and going back to 2000, before any such digital cameras existed) is that
they consider 35mm film about the equivalent of 6 megapixels. It's not
exact, as it depends on what image sensor (not all image sensors of the same
megapixels are the same) and what film (not all 35mm films are the same,
either). The lens obviously enters into overall image quality in a big way,
but that is equally true for both film and digital cameras. But bottom
line, as a rule-of-thumb, and other things (in particular the lens) being
equal or at least comparable, I consider (and a lot of experts consider)
that about a 6 megapixel camera is the equivalent of 35mm film.
8 Aug
8 Aug
1:58 p.m.
New subject: OT: Re: VCF Suggestions (film vs. digital cameras)
On Mon, 8 Aug 2005 14:53:20 -0400
"Barry Watzman" <Watzman at neo.rr.com> wrote:
I consider (and a lot of experts consider)
that about a 6 megapixel camera is the equivalent of 35mm film.
http://www.kenrockwell.com/tech/mpmyth.htm
"I find that it takes about 25 megapixels to simulate 35mm film"
6 "true" color megapixels are 24 "false" megapixels. The megapixel
count
the manufacturers print in their ads actually is the count of the
"false" (i.e. bayer sub-) pixels. Based on those subpixels you can
interpolate one "false" color pixel per bayer subpixel. Obviously
interpolated pixels are not real color pixels so you get interpolation
artifacts like moire effects...
A bayer pixel is formed like this:
R G
G B
i.e. four subpixels per color pixel. Two subpixels are green, one red
and one blue. There are two green subpixels because the human eye is
very sentive for green shades. Based on this the camera interpolates one
"false" color pixel for each subpixel. Therefore the count of real color
pixels is one quater of the number the manufacturer prints on the box...
This is obviously not true for cameras with three CCD / CMOS image
sensors. There you get only "real" color pixels, no interpolation
required. But: Is there any DSLR with three CCD / CMOS sensors?
Lets do some math: An A4 paper is about 8" to 12". The minimum
resolution a print requires to hide the pixel structure is 300 dpi.
(This is not good, it is the minimum!) 300 dpi gives 90000, say 100000
pixels per square inch. The print is about 8" * 12" = 96 square inch,
say 100 square inch. So you get 100000 pixels per square inch * 100
square inch = 10 megapixel. True pixels, not interpolated bayer
subpixels. I.e. you will need a 40 megapixel camera to get this. OK, you
may get away with the interpolated pixels, so a 10 megapixel DSLR can do
this job.
Not to talk about color depth... (e.g. digicams use RGB, i.e. additive,
printers CMYK, i.e. subtractive color models. Conversion frome one to
the other is lossy.)
Or think about a slide show. How much does a digital projector cost that
can project your 10 megapixel digital images at full resolution? Good,
old, analog slides will get you there much cheaper.
You may get away with even less then 10 megapixels depending on the
subject, how good the interpolation works and most important how high
your demand for quality is.
Still, for real fine art, e.g. architecture, photography and large
prints, e.g. 30 cm * 40 cm and above, a large format camera is the way
to go. Period.
--
tsch??,
Jochen
Homepage: http://www.unixag-kl.fh-kl.de/~jkunz/
2:47 p.m.
Re: "I reckon that a good 35mm camera (good meaning a top-end lens and
fine grain film) is equivalent to 12-20 megapixels."
My understanding from the camera companies, which I've heard more than once
(and going back to 2000, before any such digital cameras existed) is that
they consider 35mm film about the equivalent of 6 megapixels. It's not
This may well be the case for a reasonable compact camera with a zoom
lens, and normal colour print film processed in the the local overnight
photo shop (actually, I think 6Mpixels is better than that...). I also
think that a top-end fixed focal length lens, fine grain film, and
careful processing/printing will be a lot better than that.
-tony
9 Aug
9 Aug
6:40 a.m.
On Mon, 08 Aug 2005 23:47:54 +0200, Tony Duell <ard at p850ug1.demon.co.uk>
wrote:
An excellent lens and high-resolution B&W film may give you up to 100
lp/mm.
The pixel depth will be 12 bits or more.
A 36mm wide negative will accomodate 3600 line pairs or 7200 pixels.
To reliably resolve that digitally without artifacts, the Nyquist theorem
tells us we need at least 14400 pixels.
The equivalent photodetector to match high-resolution film will then be
9600x14400, giving us 138240000 or for short 138 megapixels.
High quality colour film can resolve around 64 lp/mm. This will give us
3072x4608. Assuming a normal lens will work as a low pass filter, we
forget about Nyquist and end up with 14155776 as the lower limit for 35mm
equivalent quality,
I suspect that pixel depth is the biggest problem with current detectors.
When I scan my slides, 3x12 bits per pixel is the minimum to avoid quality
loss. With a scanner, you can easily gain another but by doubling the
number of passes. This does not work with a camera, the detector needs to
have enough depth (signal/noise ratio) to begin with,
--
Bj?rn
Re: "I reckon that a good 35mm camera (good meaning a top-end lens and
fine grain film) is equivalent to 12-20 megapixels."
My understanding from the camera companies, which I've heard more than
once
(and going back to 2000, before any such digital cameras existed) is
that
they consider 35mm film about the equivalent of 6 megapixels. It's not
This may well be the case for a reasonable compact camera with a zoom
lens, and normal colour print film processed in the the local overnight
photo shop (actually, I think 6Mpixels is better than that...). I also
think that a top-end fixed focal length lens, fine grain film, and
careful processing/printing will be a lot better than that.
7076
days inactive
7077
days old
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ard＠p850ug1.demon.co.uk -
aw288＠osfn.org -
bv＠norbionics.com -
jkunz＠unixag-kl.fh-kl.de -
Watzman＠neo.rr.com