>On Lun, 16 mar 1998 7:15, MR THOMAS N CURLEE <mailto:JNVS44B@xxxxxxxxxxx>
>wrote:
>>With 25.4 mm/inch, then a 35 mm frame is 25.4 X 100 by 1.5 X 25.4 X
>>100. This is 9.68 million pixels. With 30 bits per pixel (assume 4
>>bytes) this is 38.7 MB per photo. Note that many cam corders
>>advertise 300K-400K pixel resolution. Without image compression wee
>>would need a 1.4 GB hard drive to store a 36 exposure 'roll'.
>>
>
>Actually, a "line" is equivalent to two "pixels". So your number should be
>multiplied for 4. But we have to consider also the low contrast resolution,
>not only the high contrast one. I understand most lenses and films do
>resolve 100 lines in HC, but I guess maybe 25 or 30 in low contrast.
>Digital image has a point in this, cause the number of pixels is
>unregarding of contrast grade.
>
>Marco
>mailto:tom@xxxxxxxxxxxx
>
You are right that a line would be two pixels. However, the limit of
resolution of a film, camera and lens combination is not usually the
resolving power of the film. Film has much greater potential resolution
than a lens as you can see from old tests that counted lines per
millimeter. So currently, if the lens can resolve it film can record it.
You seem to be saying that the image recording power of pixels is
independent of contrast, which I don't believe is true. My experience is
that bad scan is a bad scan and while you may be able to improve it a
little it cannot put back information that was never recorded. Regardless
of that I don't think I would be pleased with an image that had the same
resolution, though even, as the edge resolution of my worst lens, even
assuming a pixellated point and shoot could come close to that.
Also, no one has commented that you don't have to convert from inches to
millimeters to find the size of a 35 mm frame. Film is metric. The size of
a 35 mm frame is 24mm by 36mm by international agreement.
Probably the reason for lack of such a comment is that except for a couple
of details, Mr. Curlee's calculations point out the obvious, that for now
film is a pretty secure medium for people who care about quality photos.
Just an afterthought: Olympus today announced a new camera line with 1.2
megapixels maximum resolution. As you can see from Mr. Curlee's
calculations, that is not even close to film.
Winsor Crosby
Long Beach, California
mailto:wincros@xxxxxxxxxxx
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