There are many factors, not just the lens, that go into image quality.

   Since you are talking about different formats (size of film - sensor) it
is really difficult to compare lenses.

   Small lenses are easier to make well.

   Lens design has improved over the years due to computer designs, better
glass etc.

   Post exposure processing has been a plus in many ways (also a scourge in
others).

   If you had a full size 35mm digital SLR you would have a better
opportunity to compare apples to apples and I believe you would find that
apples are apples.   The lenses are not all that different.  We still have
good ones and some not so good and a few great.

[]

One reason is that they are no longer required to fit the SLR format, with
its mirror making the lens back-focal length requirement much greater.
Design and manufacture have, of course, improved over the years as well.

David

One of the things that makes some lenses on smaller, cheaper cameras
work so well is that they have a smaller aperture (higher min. f/#). It
is always easier to design and build a lens of smaller aperture.
Lenses of larger aperture (lower f/#) are more complex even stopped
down.

Both the higher f/# and the shorter focal length gives you some
additional depth of field.  Design techniques and fab techniques have
advanced in last two decades.

Note that the smaller aperture is common even on compact 35mm cams, not
just digitals.

It is as bit more complicated comparing digitsl to film, because on digital
the lens is not the only factor that determines the quality of the image.

I started in 35mm in 1973, with a Spotmatic IIa, which I still have, along
with another dozen or so bodies.  In my case, I did not want to abandon my
familiar film gear, so I went with a film scanner, and I am quite content
with that arrangement.  My requirements are modest, and I shoot only a roll
per week, if that.

I have had a 2.3MP digicam since 2000.  It was prosumer when it was
released, and I have always been quite pleased with its results.
Nine-element, all glass lens.  Remote control (great as a substitute for a
cable release when camera is on a tripod).  And I always have my film gear
when I require higher resolution images.

The film scanner has, in a sense, turned all of my film cameras into digital
cameras.  Since I don't have large expenditures for film and processing,
this setup works well for me.

If you still have your Spotmatics, and if you are the lower-volume shooter
that your post suggests, you too might want to consider trying a film
scanner, rather than starting over with digital bodies and their lenses, and
paying a fortune to replicate what you already have in the film domain.
This approach is probably unsuitable for people that shoot lots of images.

I rarely see reviews of lenses for digital cameras, and current software
like PSP or PS can correct for things like pinsuchion and barrel distortion,
digital noise reduction, chromatic aberration ("purple fringing"), and
perspective correction ("falling buildings").  It can also increase or
decrease sharpening, allowing you to mimic characteristics of specific
lenses.  So the lens itself is not longer as critical a factor as it was
back in the days when shooting transparencies--when it was just the lens and
the film, with no intermediate influences.

My sense is that it is easier to use less-than-stellar lenses with digital
photography, since the images can be tweaked during the editing stage.  It
may take additional time to tweak the images, a problem for professionals
for whom time is money, but we amateurs have a different set of requirements
than pros do.

For family photos of 8 x 10 or smaller, your choices are broad.  Most
digicams are perfectly well-suited to that type of photography.  I would say
that your ability to exploit the features of your editing software is
probably more important than your choice of camera, for such shots.

Digital P&S cameras are becoming more like commodities.  Manufacturers are
struggling to define niches that separate their products from the rest of
the pack, but any feature of value can be easily mimiced by other
manufacturers within 6 months, when the latest updated models come out.  For
my part, I've stopped trying to stay on top of the latest developments--my
film cameras do exactly whet I want them to do, I already have lots of gear,
and the film scanner enables me to take advantage of the one feature of
digital imaging that means the most to ME: that of being able to have a
digital darkroom where I can edit (and, hopefully, improve) my images prior
to printing them.  The method of capture is of no importance at all.

Takumar or Super Takumar (42mm thread) on the old Spotmatic?

So, to answer to the question in the subject:

Decades of research and technology advances in the design
and creation of lenses -- for multiple reasons:  newly-
discovered (or newly-designed) materials that lead to
higher-quality glass; better manufacturing processes
leading to lenses with fewer and less-significant defects;
better designs (partly due to computer-assisting tools
available today and not available a decade or a few
decades ago).

I mean, compare the quality of television 30 or 40
years ago with today's.  Compare the special effects
of movies 30 or 40 years ago with today's  (and I mean
the "final quality" of the effects -- not the "merit"
and the ingeniosity involved in it).  Compare the
quality of cars 30 or 40 years ago with today's (again,
the *technical quality* -- whether or not one may think
that cars were "cooler" back in those days is not an
issue here;  cars were not fuel efficient, they were
not nearly as safe -- in fact, they were barbarically
unsafe 30 years ago -- etc. etc.)

Yes, I know that there are also counter-examples to
the argument -- things in which the "mass marketing"
nature of things has completely ruined products that
used to be manufactured with higher standards of
quality  (furniture comes to mind -- although under
certain point of view, one could perhaps argue that
thy have improved technically -- easy to "assemble
yourself", easier to move and transport, more
enviro-friendly, etc.).

Carlos
--

Inexpensive high quaiity molded aspheric lens and better lens design
program are among the main reasons. The lens on my newest pocket
camera-an OLY 350-- has six elements of which rhree are apsherics and
it's close to aberation free thruout its zoom range

jpc

[A complimentary Cc of this posting was sent to
Don W
<mail@mail.invalid>], who wrote in article <Xns985083882E70A74C1H4@127.0.0.1>:

Some of these are not a tiny bit important in digital world, since
they can be 100% corrected without any (or, at least, a significant)
image degradation.

The principal reason for the effect you see is that, as it turns out,
lenses has very little effect in 35mm world: the quality of film in
35mm formfactor is so abysmal, that the *principal* damage comes from
film, not from lens.

Replacing film by a digital sensor increases several parameters so
much that a (small?) decrease in other parameters is not very
noticable.

One data point: to fully exploit the image detail provided by high
quality rangefinder lenses in the highest-resolution f-stop, one would
need to have about 80MP digital sensor.  But already a 8MP pixel
provides images which (in most people's eyes) bit the quality of film
images.

This gap (8MP to match film quality, vs. 80MP to match lens quality)
leads to the effect that even not-a-stellar lens provides quite
adequate images.

In the view of the above, I think this question does not make a lot of
sense...

Hope this helps,
Ilya