We are somewhat going in circles here. The reason that all photgraphic lenses
seem to have resolution within a factor of two of 50 line pairs per millimeter
(100 pixels per millimeter) is that this is more or less the resolution of film
of reasonable sensitivity (ASA 100 or greater), so the lenses are designed to
that resolution.
Whatever the size of the film, 35mm, 6x6, 4x5, 8x10, the film resolution is the
same, so all lenses will have more or less the same on-film resolution, with
the more expensive lenses being better, and the less expensive lenses being
worse. The limits, from the websites mentioned below, seem to range from 100
line pairs to 25 line pairs per millimeter.
Lenses can be designed to have far higher resolution, as evidenced by the
lenses used to project mask patterns onto silicon wafers during the manufacture
of integrated circuits. Basically, these lenses are diffraction-limited, with
focal spots being of order one wavelength in diameter. In the near
ultraviolet, this is about 350 nanometers, which corresponds to 2860 pixels per
millimeter. One can buy film with such resolution, but consider yourself
fortunate if the film speed exceeds ASA 1.00.
While photographic lenses are never diffraction limited at max settings,
astronomical telescopes are almost often designed to be diffraction-limited,
forming perfect airy-disk images of stars. In this, it's the main aperture
that's the limit, and on-film resolution is a lesser problem.
So, the resolution of a lens is an engineering design goal resulting from
contemplation of the target market and use, and is not a property of the
universe (except when up against the diffraction limit).
And those old, grainless photos from 100 years ago used large plates of very
low photographic sensitivity.
Joe Gwinn
At 9:47 AM +0000 12/23/02, olympus-digest wrote:
>
>Date: Mon, 23 Dec 2002 13:30:26 +0800
>From: "C.H.Ling" <chling@xxxxxxxxxxxxx>
>Subject: Re: [OM] Re: Dipping our Toe Into Digital (LONG)
>
>Thanks for the data, it looks much better than I though. Below is what
>photodo say, although I'm not totally agree with it. I believe MF and
>large format are much better than 35mm but not to the extend of...
>what 8x10 equal to 900MP of valuable data. I have never use LF, but it
>is hard to imagine.
>
>http://www.photodo.com/nav/artindex.html
>
>Check on the "35 mm, medium format, or large format?"
>
>C.H.Ling
>
>Walt Wayman wrote:
> >
> > A look here might prove informative.
> >
> > http://www.hevanet.com/cperez/testing.html
> >
> > Walt
> >
> > ---------- Original Message ----------------------------------
> > From: "C.H.Ling" <chling@xxxxxxxxxxxxx>
> > Reply-To: olympus@xxxxxxxxxxxxxxx
> > Date: Mon, 23 Dec 2002 12:39:04 +0800
> >
> > >80-100lpmm! seems that it is better than the center resolution
> > >of all lenses from Contax AF 645 MF camera I have seen from pop
> > >photo test.
> > >The LF lenses must be a magic! If you are talking about aerial
> > >resolution, may be, I'm not sure. If on film resolution, I really
> > >doubt. Check what photodo said about MF/LF resolution, they are
> > >not much better than 35mm.
> > >
> > >C.H.Ling
> >
> >
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