Digital P/S - lousy lens performance

I was looking at the digital camera performance in the DPRP reviews on
http://www.dcresource.com/reviews/cameraList.php and I was surprised at
the barrel distortion that every camera seemed to experience. Perhaps
that's the nature of the beast with zoom lenses, but I would have
thought that Leica (the best of the bunch), Canon, Nikon, and Carl
Zeiss, to name a few, would have corrected their lenses better.
I'm used to using fixed lenses so I don't see those types of
distortions. Do all zoom lenses, whether 35mm or digital, experience
that level of distortion?

Nathantw

Re: Digital P/S - lousy lens performance

"y_p_w" <y_p_w@hotmail.com> writes:
Or the original poster, who was upset to find geometric distortion in
the zoom lens in a P&S camera. Geometric distortion has to be pretty
low on the list of things that most consumers care about in P&S cameras,
since you can't see moderate amounts of distortion in most shots.
Even among SLR lenses, where a much wider variety of lens tastes (and
budgets) are catered to, only the specialized macro lenses seem to pay
particular attention to low distortion. It's a niche thing, like
tilt&shift lenses.
(And, as others have pointed out, in the digital image world it's
pretty easy to correct simple barrel or pincushion distortion, or
converging verticals, so low-distortion and shift lenses aren't even as
important as they used to be in a film world).
Dave


Davem@cs.ubc.ca (Dave Martindale)

Re: Digital P/S - lousy lens performance

Just remember there are also varying price points in consumer
cameras. I recently went on vacation with my folks. I brought
along my new PowerShot S3 IS, and they used their A520.
Even adjusting for all sorts of conditions (incl resolution), I was
able to get better results. Of course my camera cost about
twice theirs, and weighed about twice as much.
That's certainly a problem with the "do everything" cameras that
people want at low price points. Of course they don't end up
doing everything well. Of course we joke a lot here about the
inquiries for an inexpensive high-zoom camera that takes
really good indoor shots without a flash. There are a lot of
unrealistic expectations out there.


Y_p_w

Re: Digital P/S - lousy lens performance

One can purchase a digital P&S, at the $200 price point, that is capable of
much more than could be bought for the same price in a film camera.
P&S cameras have their advantages, but to compare their capabilities against
those of DSLRs will always result in their coming up short.
For the typical consumer, the P&S is perfectly adequate for nearly every
photographic requirement. I like them a lot. I don't feel "stuck." I have
other cameras and lenses for more demanding situations.
The factor that causes the most confusion is the notion that one should
choose a single camera. The quest to find the one camera that can do
everything can drive one to the brink of insanity. The equation often has
no solution.
I have opted to keep my film SLRs and lenses for the more exacting work, and
to use my digital P&S as my walkabout camera. There is little need for me
to abandon all my film gear. It is really nice to be able to tote a
lightweight P&S virtually everywhere, rather than to agonize over which body
and lenses to include in my kit. What typically happened is that I carried
no camera at all, rather than lug all that junk around.
Now I take more shots, using less equipment. The P&S has given me a sense
of empowerment, by freeing me from the drudgery of having to carry multiple
lenses and accessories around. Despite its limitations I think it is a good
tradeoff.


Jeremy

Re: Digital P/S - lousy lens performance

"y_p_w" <y_p_w@hotmail.com> writes:
It's a single focal length lens with a moderate field of view,
neither wide nor tele. That makes it easier to get good performance at
relatively low cost. If you just took that design and scaled it down by
a factor of 5 (scaling all the dimensions and radii and tolerances),
you'd get a lens that worked well on a P&S digicam.
But consumer P&S cameras don't come with fixed lenses, they come with
zooms due to market demand. Except for fairly high-end P&S cams, those
zooms tend to be relatively slow as well. And just like low-cost zooms
for 35 mm cameras, performance is not up to the standards of that simple
50 mm single focal length lens.
In any case, zooms generally have more distortion than single FL lenses.
That doesn't make them "lousy" performers; they're just optimized for
other things. If you must have low distortion, stick to single FL
lenses. Or use only true macro lenses, which are optimized for good
correction and very low distortion (but trade away other things).
It's more the case that with a DSLR you have more choice: you can buy a
stable of fast sharp fixed FL lenses, or a couple of cheap slow zooms, or
a few really expensive but higher performance zooms. With a P&S, you're
stuck with whatever set of tradeoffs the manufacturer decided on for
that camera.
Dave


Davem@cs.ubc.ca (Dave Martindale)

Re: Digital P/S - lousy lens performance

Bear in mind that most "point and shoot" cameras have a relatively wide zoom
range--compare with zooms for SLRs with the equivalent range and you'll
find that they generally have significant distortion at the wide end of the
range. If you look at fixed focal length wides you'll find that there is
sometimes but not always significantly lower distortion, and some lenses
have sweet spots at certain focal lengths where the distortion is very low.
Dcresource seems to show the worst case and doesn't quantify the
distortion--take a look at <http://www.photozone.de> for more detailed
reporting on Canon and Nikon DSLR lenses. Note for example the performance
of the Canon 10-22mm at 14mm and the 18-70 at 24mm, in both cases the
distortion is less than a tenth of a percent, and considerably better than
many fixed focal length lenses achieve. One of these days I'm going to get
around to running their test suite on the point-and-shoots I have in my
possession just to see how they do.
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)


J. Clarke

Re: Digital P/S - lousy lens performance

However - I'm told that an $80 Canon EF 50mm Mk II is an
absolutely incredible lens apart from the build quality. It's
made of a lot of plastic, which would make it similar to the
materials used in most consumer digicam lenses.
However - 35mm-equivalent zoom lenses seem to be more
of "you get's what you pays for."


Y_p_w

Re: Digital P/S - lousy lens performance

High-end SLR lenses can eaily get into the $5000 range. You're talking
about a complete camera that costs probably less than 1/10 that.
The math is simple.


Matt Ion

Re: Digital P/S - lousy lens performance

...
All camera systems are compromises in one form or another. I understand
that the latest version of PS has a feature that corrects for lens
distortion of the kinds you mentioned. That is a feature that will almost
certainly be adopted by every image editing program in the future. So lens
distortion might not be quite the major issue that it would have been.
Given the low cost of P&S digicams, I think you may be nitpicking. You get
a lot for the money, but one can't expect 100% perfection.


Jeremy

Re: Digital P/S - lousy lens performance

...
Any lens design has to trade off a variety of aberrations, get rid of one
and another will get much worse.
Zoom lenses are much more complicated than fixed focal length lenses, so it
is not surprising that barrel and pincushion are usually available at
opposite ends.
Your remark about fixed lenses is not strictly true. Most of the wides or
teles, even the good makes, show some tendency to one or the other, but in
very small doses.
Roy G


Roy G

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