lens sharpness & performance focused near vs. far

Bakhuys wrote:


Table 39.1 (incomplete)

"general photography (0.1), close-up (0.1-1), photomacrography (1-50)."

So many so called macro shots are really close-up shots, even when done
with
a macro lens. It;s magnification what counts. I think Ray's terminology is
right.

Maybe, not not in accordance with general usage.
Anything he calls close-up and (!) photomacrography is normally called
"macro" (except by Nikon, who call it "micro" ;-)).

However, i don't see how terminology is important. The question is whether
lenses can be used over a wide range of distances or not. Right?

Recently, Q.G. de Bakker posted:

Bakhuys wrote:


Table 39.1 (incomplete)

"general photography (0.1), close-up (0.1-1), photomacrography
(1-50)."

So many so called macro shots are really close-up shots, even when
done with a macro lens. It;s magnification what counts. I think
Ray's terminology is right.

Maybe, not not in accordance with general usage.
Anything he calls close-up and (!) photomacrography is normally called
"macro" (except by Nikon, who call it "micro" ;-)).

However, i don't see how terminology is important. The question is
whether lenses can be used over a wide range of distances or not.
Right?

There seem to be several questions on the table at this point. ;-)

* What qualifies as a macro lens?

* How do macro lenses perform at infinity?

And, introduced as a comment that I took to suggest that macro lenses are
misnamed, "But as often terminology has been confused, often by marketing
people (APO is another example: few, if any, designs for photograpy are
true
APO's)", to which I can only say "Oh?". ;-)

So... perhaps terminology is quite important to this discussion, because
the lenses that one believes to work well at infinity as well as "close
up" may be in some way distinguishable from "macro lenses". ;-)

I'm interested to see how this all settles out; then perhaps I'll know how
to properly define my 100 mm APO-Macro Elmarit beyond just calling it an
exceptional performer across its entire range of focussing distances. ;-)

Regards,

Neil

Neil Gould wrote:

There seem to be several questions on the table at this point. ;-)

Yes. And i'm sure we can table a whole bunch more so that at some moment in
the near future...
;-)

* What qualifies as a macro lens?

* How do macro lenses perform at infinity?

And, introduced as a comment that I took to suggest that macro lenses are
misnamed, "But as often terminology has been confused, often by marketing
people (APO is another example: few, if any, designs for photograpy are
true
APO's)", to which I can only say "Oh?". ;-)

"Apo" has been the "Turbo" of optics, has it not?
The term was bandied about as if it had no real meaning, as if it didn't
describe some real feat.

So... perhaps terminology is quite important to this discussion, because
the lenses that one believes to work well at infinity as well as "close
up" may be in some way distinguishable from "macro lenses". ;-)

I'm interested to see how this all settles out; then perhaps I'll know how
to properly define my 100 mm APO-Macro Elmarit beyond just calling it an
exceptional performer across its entire range of focussing distances. ;-)

Another good example, very similar to the Zeiss/Contax f/4 Makro-Planar, of
a not-really-symmetrical double Gauss type lens, put in front of a two-lens
group of thick chunks of glass, destroying any residual semblance of
symmetry.
And those two thick pieces of glass (floating elements, staying put while
the rest of the lens moves) were put there to improve performance at close
range... Put there to turn a somewhat symmetrical "normal" lens into a macro
lens... ;-)

Leica claims the "unsurpassed performance" of this lens is equally good from
infinity to 1:2. (But then, Leitz claims a lot. ;-))

Funny though, but the make-up of this lens, with that funny rear lens group,
apparently makes using close-up lenses to get even closer than the barrel
allows the preferred option. Preferred over using extension tubes.
That while close-up lenses are poor thingies, suffering from (and passing
on!) every lens aberration in the book.

Roland, please answer the question I asked. Name lenses, define
symmetry. Surprise me with true facts I don't already know.
Otherwise, subdue your ego and shut up.

Your answer is irrelevant and wrong. Not only that, its inconsistent
with some of the expletive you've spouted elsewhere in this thread.
In particular, at 1:1, which you see as some sort of magical dividing
line, the front node to subject distance is 2f, not f.

"Q.G. de Bakker" wrote in message
...


The faster lens bit:
Slow lenses are easier to optimize than fast lenses, so slow lenses
generally perform better. I don't know if modern lens design made a
difference.

Many people appear to like the faster lenses not because they perform
better
(because the really fast ones generally do not. They may be excellent in
the
image center, but performance drops off rather fast going away from the
center) but for other qualities they posess (like shallow depth of field).


OK, so I've found the site that does the MTF tests (www.photodo.com), and on
the face of it, of the two Canon EF 28mm lenses, the f/2.8 ($160) lens beats
the f/1.8 lens ($390) hands down, at every shared aperture. In fact, the
poor f/1.8 lens fares about as well as the 28-80mm USM consumer-grade
cheapie. (Incidentally, my experience has been that "consumer-grade" zooms
aren't automatically crap; I had a Nikkor 35-80 that seemed quite sharp,
though I never did lens tests per se.)

My point was that all the tests reported at this site were apparently done
with lenses set to infinity. Isn't it possible the Canon designers realized
someone choosing the faster lens would most likely do so for available light
photography, which is generally done within 20 meters or so? In which case,
if one can't equally pursue performance close-up and performance at
infinity, the rational designer would optimize the faster lens for
near-focus to moderate distance performance at the expense of performance at
infinity. Which would mean that for my needs, even addressing sharpness
alone and no other aspect of lens performance, the lens with the lower
Photodo grade could very well be the better lens... More generally, the
photodo ratings - which are used to compare lens resolving power - may not
always be useful even for comparing lenses within that narrow parameter
(very broad differences aside).

By the way, isn't internal focus (which moves elements relative to each
other within the lens) a relatively modern technology? Didn't older lenses
focus simply by racking the lens closer or farther from the film plane? If
so, with the older lenses, why would performance differ at ANY focal length,
since the issue is just where the film plane happens to be positioned in the
same cone of light?

"S.M.C." wrote:
"Q.G. de Bakker" wrote:

The faster lens bit:
Slow lenses are easier to optimize than fast lenses, so slow lenses
generally perform better. I don't know if modern lens design made a
difference.

FWIW, of all the lenses that Canon provides both a slow and fast version of,
the 28mm pair is the only pair in which the fast lens is inferior.

In every other case, the faster lens is the better lens. (24, 35, 50, and 85
mm lenses) Although for the 24 and 35, the difference is quite small.

OK, so I've found the site that does the MTF tests (www.photodo.com), and
on
the face of it, of the two Canon EF 28mm lenses, the f/2.8 ($160) lens
beats
the f/1.8 lens ($390) hands down, at every shared aperture. In fact, the
poor f/1.8 lens fares about as well as the 28-80mm USM consumer-grade
cheapie. (Incidentally, my experience has been that "consumer-grade" zooms
aren't automatically crap; I had a Nikkor 35-80 that seemed quite sharp,
though I never did lens tests per se.)

The 28/1.8 is widely thought to be problematical. I have one friend, though,
who gets great results with it on a 10D.

My point was that all the tests reported at this site were apparently done
with lenses set to infinity. Isn't it possible the Canon designers
realized
someone choosing the faster lens would most likely do so for available
light
photography, which is generally done within 20 meters or so?

No. The 28/1.8 is relatively poor. But it'll still take good photographs.

David J. Littleboy
Tokyo, Japan

Recently, Q.G. de Bakker posted:

Neil Gould wrote:

There seem to be several questions on the table at this point. ;-)

Yes. And i'm sure we can table a whole bunch more so that at some
moment in the near future...
;-)

Of course! ;-)

* What qualifies as a macro lens?

* How do macro lenses perform at infinity?

And, introduced as a comment that I took to suggest that macro
lenses are misnamed, "But as often terminology has been confused,
often by marketing people (APO is another example: few, if any,
designs for photograpy are true
APO's)", to which I can only say "Oh?". ;-)

"Apo" has been the "Turbo" of optics, has it not?
The term was bandied about as if it had no real meaning, as if it
didn't describe some real feat.

The salient term is "as if". Some turbo installations may technically
qualify, but underperform. Why should lens marketing be any different?

I'm interested to see how this all settles out; then perhaps I'll
know how to properly define my 100 mm APO-Macro Elmarit beyond just
calling it an exceptional performer across its entire range of
focussing distances. ;-)

Another good example, very similar to the Zeiss/Contax f/4
Makro-Planar, of a not-really-symmetrical double Gauss type lens, put
in front of a two-lens group of thick chunks of glass, destroying any
residual semblance of symmetry.

And those two thick pieces of glass (floating elements, staying put
while the rest of the lens moves) were put there to improve
performance at close range... Put there to turn a somewhat
symmetrical "normal" lens into a macro lens... ;-)

Leica claims the "unsurpassed performance" of this lens is equally
good from infinity to 1:2. (But then, Leitz claims a lot. ;-))

Leitz often delivers, as well. So far, my usage can't discredit that
claim. ;-)
I am not at all disappointed with this lens' performance, but its handling
can be an issue at times, as it can take some time to focus properly due
to its long throw. For me, that makes it less than ideal for candids.

Funny though, but the make-up of this lens, with that funny rear lens
group, apparently makes using close-up lenses to get even closer than
the barrel allows the preferred option. Preferred over using
extension tubes.
That while close-up lenses are poor thingies, suffering from (and
passing on!) every lens aberration in the book.

This recommendation is likely to be more a matter of convenience than
optimal quality. If you want to get more magnification and optimal
quality, it may be time to look at a bellows.

Regards,

Neil

Recently, Bakhuys posted:

"Neil Gould" wrote in message

I'm interested to see how this all settles out; then perhaps I'll
know how to properly define my 100 mm APO-Macro Elmarit beyond just
calling it an exceptional performer across its entire range of
focussing distances. ;-)


Probably not a macro lens because you need a close up attachement for
that lens to reach 1:1 ;-)

Or, possibly, that requirement is somewhat arguable? If everyone makes a
"macro" lens that limited to less than 1:1, does that not affect the
definition of "macro"? ;-)

Maybe it's a true APO. I just read about a Leica (Leitz) lens (APO
Telyt-R design) which didn't need an infrared index because of it's
excellent color correction up to 900 nm wavelenght: sure this is
probably one of the very few true APO's. APO lenses are capable of
producing three images of identical size with three different colors,
BTW.

I'd think that to be a requirement of an APO. That's the target, but
quality control determines what you actually get.

No doubt your lens is an exellent performer at close up ánd infinity.
But I guess you will find even sharper lenses at infinity in the
Leica range? Not that it will make much difference in practise (at
f/8 or so).

Perhaps, but it's the sharpest Leica lens that I own, so I can't confirm
or deny the existence of a superior example.

Regards,

Neil

Neil Gould wrote:

Or, possibly, that requirement is somewhat arguable? If everyone makes a
"macro" lens that limited to less than 1:1, does that not affect the
definition of "macro"? ;-)

It depends on the context in which the words are used. In technical
works "macro", "photomacrography" and "macro-photography" always
refer to conditions where the image size is greater than or equal
to the object size. If you can find a single serious technical
work on photography which uses "macro" where the image size is
smaller than the object size then I'd like a citation.

In marketing literature the word "macro" has been frequently used
to describe lenses which are primarily intended for use where
the image size is somewhat smaller than the object size.

So if you are using the technical sense of "macro" a Leica
APO-Macro Elmarit-R is not a macro lens. A Leica Photar
(or an old Leitz Micro-Summar) is a macro lens because it
is designed primarily for photography where the image is
larger than the object.

Most photographers read more marketing literature than
technical literature so it isn't surprising that the
meaning used in marketing literature is the one that is
usually understood.

Peter.
--

Neil Gould wrote:

Or, possibly, that requirement is somewhat arguable? If everyone makes a
"macro" lens that limited to less than 1:1, does that not affect the
definition of "macro"? ;-)

It depends on the context in which the words are used. In technical
works "macro", "photomacrography" and "macro-photography" always
refer to conditions where the image size is greater than or equal
to the object size. If you can find a single serious technical
work on photography which uses "macro" where the image size is
smaller than the object size then I'd like a citation.

In marketing literature the word "macro" has been frequently used
to describe lenses which are primarily intended for use where
the image size is somewhat smaller than the object size.

So if you are using the technical sense of "macro" a Leica
APO-Macro Elmarit-R is not a macro lens. A Leica Photar
(or an old Leitz Micro-Summar) is a macro lens because it
is designed primarily for photography where the image is
larger than the object.

Most photographers read more marketing literature than
technical literature so it isn't surprising that the
meaning used in marketing literature is the one that is
usually understood.

Peter.
--