Telephoto Reach and Digital Cameras - lens comparison

me wrote:
On Fri, 17 Dec 2010 07:43:54 -0700, "Roger N. Clark (change username
to wrote:


I have not seen any zoom ;ens that will work well with stacked TCs,
because zoom lenses are not that sharp.

Only because Canon doesn't make anything in the class of the Nokon
200-400mm f/4 VR Ior II.

You are right. Canon does not make anything in the class of the
200-400 VR (I wish they did). But as good as that lens is, it is
still not nearly as sharp as the fixed focal length super telephotos.
It would show a lot of softness with stacked TCs.

Roger

Dialogue of Roger and SZ condensed to:


You are not getting it. Simple physics proves you are wrong.
Regarding image detail, the super zoom P&S cameras have clear
apertures on the order of an inch or less. Diffraction from
such a small lens means poor subject resolution. A DSLR with
even a lower end fixed telephoto like 300 f/4 has about a 3-inch
clear aperture, thus on the order of 3x higher resolution
on a subject. The 3x larger diameter lens delivers 9x
more light. More light = finer gradations due to better
signal-to-noise ratio. Again, this is simple physics.

There is no contest between a DSLR versus P&S whether telephoto
resolution on a subject or color tonality, or signal-to-noise
ratio. Simple physics, the DSLR wins.

You are wrong. It has to do with both lens physics and sensor
physics. Consider two cameras, one with double the sensor size,
double the lens focal length, and double the pixel size, and the same
f/ratio lens. The lens has 4 times the area so collects 4 times the
light. The sensors have the same spatial resolution, but the larger
pixels collect 4 times the light from the lens delivering 4 times the
light. The signal-to-noise ratio is double on the large sensor camera.
The higher signal-to-noise ratio delivers finer tonality and greater
dynamic range. This is well proven and simple physics.



As for your physics proving everything, it FAILS because it does NOT take
into account the figure of the lenses. The lenses on the superzoom camera
can and ARE polished to diffraction-limited quality. They have to be in
order to allow the photosites resolve individual details. Otherwise nobody
would buy them. Thereby allowing them to have more resolution at larger
apertures. DSLR glass is NEVER ground to diffraction-limited quality,
because the cost to do so puts them outside the reach of every consumer,
therefore they can never attain diffraction-limited resolutions at ANY
useful aperture.


What a laugh! Physics does very well. Again it is simple physics
that shows that the big lenses with DSLRs doesn't even need to be close
to diffraction limited in other to deliver better resolution on a subject
compared to the tiny lenses on P&S super zoom cameras.
Simple physics proves it.

Simple equation:
Dawes limit = 5.45/D where D=lens clear aperture diameter.
You can try shoving the physics wherever you want to but it won't
change the basic and well understood laws of physics.


I think the problem here is that SZ thinks "diffraction
limited" somehow translates to "diffraction eliminated," and (
in his / her mind) that ultimately means "better."


Just because a fine polish can reduce the amount of
diffraction on a small lens element, it does not follow that
there miraculously is no dispersion ((or even) less
dispersion) of light across the resulting smaller focal plane
by utilizing those tiny elements in a minimalistic design.
The resultant camera is smaller and cheaper to build, and
yields satisfactory results for many situations, but it is
still physically impossible for it to exceed the images
produced by DSLR's.

I find this discussion rather interesting, since those in the
superzoom camp don't seem to realize that the whole idea of
eliminating diffraction is more than a bit counter productive,
in that diffraction is a key factor in what the human eye
actually perceives.

I mean, what we normally see is an image that stems from solar
light as defused through the atmosphere and diffracted through
the lens of the human eye. Accordingly, there is no "
perfectly clear" image prototype we can use as a standard.


From an artistic perspective, diffraction is good. Think
about it. We take a prism, shine a light through it and,
voila, a rainbow of colour appears! Translate that to the
curved surface of a lens and it doesn't take much imagination
to understand how a bit of diffraction can dramatically spruce
up the colours in an ordinary scene.

On the other hand, from a more clinical point of view, if all
one is interested in is detail, one might prefer a more
sterile capture if all one is after is the systematic
verification of a physical phenomena.
It is the natural defusion and diffraction of light our mind
decodes in order to render the rich tapestries we conceive to
physically be situated there in front of us.

We like variation. As such, if we actually could remove
diffraction and defusion from human sight, effectively
reducing what we see down to the finite number of colours and
shades physically constituting the objects we capture in our
viewfinders, I'm sure we'd be rather bored with the bland
results.

Take Care,
Dudley

Dudley Hanks wrote:

Dialogue of Roger and SZ condensed to:


You are not getting it. Simple physics proves you are wrong.
Regarding image detail, the super zoom P&S cameras have clear
apertures on the order of an inch or less. Diffraction from
such a small lens means poor subject resolution. A DSLR with
even a lower end fixed telephoto like 300 f/4 has about a 3-inch
clear aperture, thus on the order of 3x higher resolution
on a subject. The 3x larger diameter lens delivers 9x
more light. More light = finer gradations due to better
signal-to-noise ratio. Again, this is simple physics.

There is no contest between a DSLR versus P&S whether telephoto
resolution on a subject or color tonality, or signal-to-noise
ratio. Simple physics, the DSLR wins.

You are wrong. It has to do with both lens physics and sensor
physics. Consider two cameras, one with double the sensor size,
double the lens focal length, and double the pixel size, and the same
f/ratio lens. The lens has 4 times the area so collects 4 times the
light. The sensors have the same spatial resolution, but the larger
pixels collect 4 times the light from the lens delivering 4 times the
light. The signal-to-noise ratio is double on the large sensor camera.
The higher signal-to-noise ratio delivers finer tonality and greater
dynamic range. This is well proven and simple physics.



As for your physics proving everything, it FAILS because it does NOT take
into account the figure of the lenses. The lenses on the superzoom camera
can and ARE polished to diffraction-limited quality. They have to be in
order to allow the photosites resolve individual details. Otherwise nobody
would buy them. Thereby allowing them to have more resolution at larger
apertures. DSLR glass is NEVER ground to diffraction-limited quality,
because the cost to do so puts them outside the reach of every consumer,
therefore they can never attain diffraction-limited resolutions at ANY
useful aperture.


What a laugh! Physics does very well. Again it is simple physics
that shows that the big lenses with DSLRs doesn't even need to be close
to diffraction limited in other to deliver better resolution on a subject
compared to the tiny lenses on P&S super zoom cameras.
Simple physics proves it.

Simple equation:
Dawes limit = 5.45/D where D=lens clear aperture diameter.
You can try shoving the physics wherever you want to but it won't
change the basic and well understood laws of physics.


I think the problem here is that SZ thinks "diffraction
limited" somehow translates to "diffraction eliminated," and (
in his / her mind) that ultimately means "better."


Just because a fine polish can reduce the amount of
diffraction on a small lens element, it does not follow that
there miraculously is no dispersion ((or even) less
dispersion) of light across the resulting smaller focal plane
by utilizing those tiny elements in a minimalistic design.
The resultant camera is smaller and cheaper to build, and
yields satisfactory results for many situations, but it is
still physically impossible for it to exceed the images
produced by DSLR's.

I find this discussion rather interesting, since those in the
superzoom camp don't seem to realize that the whole idea of
eliminating diffraction is more than a bit counter productive,
in that diffraction is a key factor in what the human eye
actually perceives.

I mean, what we normally see is an image that stems from solar
light as defused through the atmosphere and diffracted through
the lens of the human eye. Accordingly, there is no "
perfectly clear" image prototype we can use as a standard.


From an artistic perspective, diffraction is good. Think
about it. We take a prism, shine a light through it and,
voila, a rainbow of colour appears! Translate that to the
curved surface of a lens and it doesn't take much imagination
to understand how a bit of diffraction can dramatically spruce
up the colours in an ordinary scene.

On the other hand, from a more clinical point of view, if all
one is interested in is detail, one might prefer a more
sterile capture if all one is after is the systematic
verification of a physical phenomena.
It is the natural defusion and diffraction of light our mind
decodes in order to render the rich tapestries we conceive to
physically be situated there in front of us.

We like variation. As such, if we actually could remove
diffraction and defusion from human sight, effectively
reducing what we see down to the finite number of colours and
shades physically constituting the objects we capture in our
viewfinders, I'm sure we'd be rather bored with the bland
results.

Take Care,
Dudley



Oh, yeah, I forgot to add:

"Beauty is in the mind of the Beholder, not the eye."


Take Care,
Dudley

Dudley Hanks wrote:

Dudley Hanks wrote:

Dialogue of Roger and SZ condensed to:


You are not getting it. Simple physics proves you are wrong.
Regarding image detail, the super zoom P&S cameras have clear
apertures on the order of an inch or less. Diffraction from
such a small lens means poor subject resolution. A DSLR with
even a lower end fixed telephoto like 300 f/4 has about a 3-inch
clear aperture, thus on the order of 3x higher resolution
on a subject. The 3x larger diameter lens delivers 9x
more light. More light = finer gradations due to better
signal-to-noise ratio. Again, this is simple physics.

There is no contest between a DSLR versus P&S whether telephoto
resolution on a subject or color tonality, or signal-to-noise
ratio. Simple physics, the DSLR wins.

You are wrong. It has to do with both lens physics and sensor
physics. Consider two cameras, one with double the sensor size,
double the lens focal length, and double the pixel size, and the same
f/ratio lens. The lens has 4 times the area so collects 4 times the
light. The sensors have the same spatial resolution, but the larger
pixels collect 4 times the light from the lens delivering 4 times the
light. The signal-to-noise ratio is double on the large sensor camera.
The higher signal-to-noise ratio delivers finer tonality and greater
dynamic range. This is well proven and simple physics.



As for your physics proving everything, it FAILS because it does NOT take
into account the figure of the lenses. The lenses on the superzoom camera
can and ARE polished to diffraction-limited quality. They have to be in
order to allow the photosites resolve individual details. Otherwise nobody
would buy them. Thereby allowing them to have more resolution at larger
apertures. DSLR glass is NEVER ground to diffraction-limited quality,
because the cost to do so puts them outside the reach of every consumer,
therefore they can never attain diffraction-limited resolutions at ANY
useful aperture.


What a laugh! Physics does very well. Again it is simple physics
that shows that the big lenses with DSLRs doesn't even need to be close
to diffraction limited in other to deliver better resolution on a subject
compared to the tiny lenses on P&S super zoom cameras.
Simple physics proves it.

Simple equation:
Dawes limit = 5.45/D where D=lens clear aperture diameter.
You can try shoving the physics wherever you want to but it won't
change the basic and well understood laws of physics.


I think the problem here is that SZ thinks "diffraction
limited" somehow translates to "diffraction eliminated," and (
in his / her mind) that ultimately means "better."


Just because a fine polish can reduce the amount of
diffraction on a small lens element, it does not follow that
there miraculously is no dispersion ((or even) less
dispersion) of light across the resulting smaller focal plane
by utilizing those tiny elements in a minimalistic design.
The resultant camera is smaller and cheaper to build, and
yields satisfactory results for many situations, but it is
still physically impossible for it to exceed the images
produced by DSLR's.

I find this discussion rather interesting, since those in the
superzoom camp don't seem to realize that the whole idea of
eliminating diffraction is more than a bit counter productive,
in that diffraction is a key factor in what the human eye
actually perceives.

I mean, what we normally see is an image that stems from solar
light as defused through the atmosphere and diffracted through
the lens of the human eye. Accordingly, there is no "
perfectly clear" image prototype we can use as a standard.


From an artistic perspective, diffraction is good. Think
about it. We take a prism, shine a light through it and,
voila, a rainbow of colour appears! Translate that to the
curved surface of a lens and it doesn't take much imagination
to understand how a bit of diffraction can dramatically spruce
up the colours in an ordinary scene.

On the other hand, from a more clinical point of view, if all
one is interested in is detail, one might prefer a more
sterile capture if all one is after is the systematic
verification of a physical phenomena.
It is the natural defusion and diffraction of light our mind
decodes in order to render the rich tapestries we conceive to
physically be situated there in front of us.

We like variation. As such, if we actually could remove
diffraction and defusion from human sight, effectively
reducing what we see down to the finite number of colours and
shades physically constituting the objects we capture in our
viewfinders, I'm sure we'd be rather bored with the bland
results.

Take Care,
Dudley



Oh, yeah, I forgot to add:

"Beauty is in the mind of the Beholder, not the eye."


Take Care,
Dudley


Before all you purists post your kindly admonishments that I
am confusing diffraction and refraction, let me just poinht
out that the two concepts are, shall we say, at worst rather
inter-related...

If the resolving power of a circular lens were only impacted
by the "diffraction" effect of waves passing around / by
obstacles, how would polishing it to a micro level make any
difference?

I view refraction as, more or less, an extension / subset of
diffraction; I'm not sure how well that goes over with the
more academic scientific community.

Take Care,
Dudley

On Fri, 17 Dec 2010 01:06:43 -0800, bobwilliams wrote:

I admire Roger's contributions to this newsgroup and take all his
data, images and conclusions very seriously.
Bob

Then you are a fool. He poses BAD SCIENCE as a way to get controversy so
people visit his website where he then tries to sell his ****-poor tourists
crapshots. He's that desperate for anyone to see his photography because
nobody wants to. It's his only motive and method. His calculations have
been proved wrong so many times in the past that people just stopped
bothering to correct all his errors. Then idiots like you fall for his
bull**** song and dance.

Superzooms Still Win wrote:

On Fri, 17 Dec 2010 01:06:43 -0800, bobwilliams wrote:

I admire Roger's contributions to this newsgroup and take all his
data, images and conclusions very seriously.
Bob

Then you are a fool. He poses BAD SCIENCE as a way to get controversy so
people visit his website where he then tries to sell his ****-poor tourists
crapshots. He's that desperate for anyone to see his photography because
nobody wants to. It's his only motive and method. His calculations have
been proved wrong so many times in the past that people just stopped
bothering to correct all his errors. Then idiots like you fall for his
bull**** song and dance.


Bob, you should listen to SZ. He's an expert on giving bad
advice and being proven wrong..

Take Care,
Dudley

On 12/17/10 2:24 PM, in article ,
"me" wrote:

On Fri, 17 Dec 2010 07:43:54 -0700, "Roger N. Clark (change username
to rnclark)" wrote:


I have not seen any zoom ;ens that will work well with stacked TCs,
because zoom lenses are not that sharp.

Only because Canon doesn't make anything in the class of the Nokon
200-400mm f/4 VR Ior II.

:-)

At least you didn't spell it as "Cannon"...

On 12/17/2010 4:26 PM, Roger N. Clark (change username to rnclark) wrote:
me wrote:
On Fri, 17 Dec 2010 07:43:54 -0700, "Roger N. Clark (change username
to wrote:


I have not seen any zoom ;ens that will work well with stacked TCs,
because zoom lenses are not that sharp.

Only because Canon doesn't make anything in the class of the Nokon
200-400mm f/4 VR Ior II.

You are right. Canon does not make anything in the class of the
200-400 VR (I wish they did). But as good as that lens is, it is
still not nearly as sharp as the fixed focal length super telephotos.
It would show a lot of softness with stacked TCs.

Which may be why I have the issue. Have you tried stacking with a 500
mirror?

--
Peter

Dudley Hanks wrote:

Before all you purists post your kindly admonishments that I
am confusing diffraction and refraction, let me just poinht
out that the two concepts are, shall we say, at worst rather
inter-related...

Dudley,
They are related in that both processes change the direction
that light travels.


If the resolving power of a circular lens were only impacted
by the "diffraction" effect of waves passing around / by
obstacles, how would polishing it to a micro level make any
difference?

I view refraction as, more or less, an extension / subset of
diffraction; I'm not sure how well that goes over with the
more academic scientific community.

It really is two different processes, and they generally work
in the opposite direction with glass lenses over the visible
spectrum. Shorter wavelengths are bent more as the light
passes through a glass lens. Diffraction affects longer
wavelengths more (red light).

But the role of polishing has little to do with diffraction performance
of a lens over the visible spectrum. Good polishing generally reduces
flare, but doesn't make the lens diffraction limited. The figure of
the polished lens has more to do with that, along with a multi-element
design to reduce chromatic and other aberrations.

So we all know who is wrong again.

Roger.

Superzooms Still Win wrote:
On Fri, 17 Dec 2010 01:06:43 -0800, wrote:

I admire Roger's contributions to this newsgroup and take all his
data, images and conclusions very seriously.
Bob

Then you are a fool. He poses BAD SCIENCE as a way to get controversy so
people visit his website where he then tries to sell his ****-poor tourists
crapshots. He's that desperate for anyone to see his photography because
nobody wants to. It's his only motive and method. His calculations have
been proved wrong so many times in the past that people just stopped
bothering to correct all his errors. Then idiots like you fall for his
bull**** song and dance.

Hmmm.. Let's look at the evidence. Throughout this thread you have
been proven wrong time and time again with simple physics.
When proven wrong you start lies. You can not prove specific
things that are in error in anything I have said in this
thread, nor on my web site. That is because the physics is
correct. So then you resort to name calling, libel, and lies.
Pathetic.

Again, simple physics proves you wrong.

So whenever you continue posting lies to this newsgroup,
everyone can respond "simple physics proves you wrong."

Roger