Nikon D800; it's going to be fascinating

To see (if the rumours are right) which model sells more, the one with an
AA filter and the one without. If enough of the ones without sell, this
will be a radical change in cameras.

"Rich" wrote in message
...
To see (if the rumours are right) which model sells more, the one with an
AA filter and the one without. If enough of the ones without sell, this
will be a radical change in cameras.

Not to open a can of worms here, but isn't anti-aliasing a good thing? Even
with a slight decrease in sharpness, I'd think it would be beneficial.

"Tim Conway" wrote in message
...

"Rich" wrote in message
...
To see (if the rumours are right) which model sells more, the one with
an
AA filter and the one without. If enough of the ones without sell,
this
will be a radical change in cameras.

Not to open a can of worms here, but isn't anti-aliasing a good thing?
Even with a slight decrease in sharpness, I'd think it would be
beneficial.

Yes, of course it is, but:

- if you use lenses with no significant response above the Nyquist
frequency, then there's nothing for the AA filter to remove. I.e. with
lenses which aren't the sharpest it doesn't matter. Put another way, if
the camera is 36 MP but the lens only 18 MP, there may be no need for AA
filtering.

- optical AA filters are imperfect, so there is a design compromise
between little filtering and some moiré, and too much filtering and loss
of sharpness (i.e. loss of high spatial frequencies). Different folk will
have different tastes and choose different degrees of AA filtering.

- there are some folk who appear to be confused about sharpness, judging
by phrases like "razor sharp" and the gross over-sharpening you see on
some people's images. Perhaps they are still using CRT monitors which
have become out-of-focus with age? G

Cheers,
David

"David J Taylor" wrote:
"Tim Conway" wrote in message
...

"Rich" wrote in message
...
To see (if the rumours are right) which model sells more, the one with
an
AA filter and the one without. If enough of the ones without sell, this
will be a radical change in cameras.

Not to open a can of worms here, but isn't anti-aliasing a good thing?
Even with a slight decrease in sharpness, I'd think it would be
beneficial.

Yes, of course it is, but:

- if you use lenses with no significant response above the Nyquist
frequency, then there's nothing for the AA filter to remove. I.e. with
lenses which aren't the sharpest it doesn't matter. Put another way, if
the camera is 36 MP but the lens only 18 MP, there may be no need for AA
filtering.

Bad idea, bad math. Sure, AA filters are a kludge (they shift (double) the
image in two directions), but they are still a much closer approximation to
a brick wall filter than lens infelicities, or even diffraction. AA filters
leave very good contrast in place at just a small fraction of Nyquist below
said frequency, which means that pretty much all detail that can be
correctly rendered actually is*. Lens resolution falloff is gradual, so if
you have a lens bad enough that it doesn't cause aliasing, then it's going
to have uninspired contrast at 1/2 Nyquist. So your 36MP camera is acting as
a poor 9MP camera if your lens is bad enough to not have aliasing problems.

*: In real life, Bayer images look really really good. The idea that there's
a problem is really quite silly.

--
David J. Littleboy
Tokyo, Japan




- optical AA filters are imperfect, so there is a design compromise
between little filtering and some moiré, and too much filtering and loss
of sharpness (i.e. loss of high spatial frequencies). Different folk will
have different tastes and choose different degrees of AA filtering.

- there are some folk who appear to be confused about sharpness, judging
by phrases like "razor sharp" and the gross over-sharpening you see on
some people's images. Perhaps they are still using CRT monitors which
have become out-of-focus with age? G

Cheers,
David

On Tue, 27 Dec 2011 09:22:35 +0900, "David J. Littleboy"
wrote:
:
: "David J Taylor" wrote:
: "Tim Conway" wrote in message
: ...
:
: "Rich" wrote in message
: ...
: To see (if the rumours are right) which model sells more, the one with
: an
: AA filter and the one without. If enough of the ones without sell, this
: will be a radical change in cameras.
:
: Not to open a can of worms here, but isn't anti-aliasing a good thing?
: Even with a slight decrease in sharpness, I'd think it would be
: beneficial.
:
: Yes, of course it is, but:
:
: - if you use lenses with no significant response above the Nyquist
: frequency, then there's nothing for the AA filter to remove. I.e. with
: lenses which aren't the sharpest it doesn't matter. Put another way, if
: the camera is 36 MP but the lens only 18 MP, there may be no need for AA
: filtering.
:
: Bad idea, bad math. Sure, AA filters are a kludge (they shift (double) the
: image in two directions), but they are still a much closer approximation to
: a brick wall filter than lens infelicities, or even diffraction. AA filters
: leave very good contrast in place at just a small fraction of Nyquist below
: said frequency, which means that pretty much all detail that can be
: correctly rendered actually is*. Lens resolution falloff is gradual, so if
: you have a lens bad enough that it doesn't cause aliasing, then it's going
: to have uninspired contrast at 1/2 Nyquist. So your 36MP camera is acting as
: a poor 9MP camera if your lens is bad enough to not have aliasing problems.
:
: *: In real life, Bayer images look really really good. The idea that there's
: a problem is really quite silly.

David's argument sounds convincing, but so do all arguments to someone as
profoundly ignorant of the underlying physics as I am. So I, a Canonian with
no dog in this hunt, propose to wait and see whether more people send their
D800's back to have an AA filter installed than send theirs back to have the
AA filter removed. If so, I guess David wins the argument. If not, I guess the
purists who dislike AA filters win. If everybody sticks with what they bought,
it's a tie. Anybody got a better way of settling it? ;^)

Bob

"David J. Littleboy" wrote in message
...
[]
- if you use lenses with no significant response above the Nyquist
frequency, then there's nothing for the AA filter to remove. I.e. with
lenses which aren't the sharpest it doesn't matter. Put another way,
if the camera is 36 MP but the lens only 18 MP, there may be no need
for AA filtering.

Bad idea, bad math. Sure, AA filters are a kludge (they shift (double)
the image in two directions), but they are still a much closer
approximation to a brick wall filter than lens infelicities, or even
diffraction. AA filters leave very good contrast in place at just a
small fraction of Nyquist below said frequency, which means that pretty
much all detail that can be correctly rendered actually is*. Lens
resolution falloff is gradual, so if you have a lens bad enough that it
doesn't cause aliasing, then it's going to have uninspired contrast at
1/2 Nyquist. So your 36MP camera is acting as a poor 9MP camera if your
lens is bad enough to not have aliasing problems.

*: In real life, Bayer images look really really good. The idea that
there's a problem is really quite silly.

--
David J. Littleboy

David,

Please note the words "may be". Yes, of course it depends on the absolute
lens MTF etc., and it was obviously not intended to be a rigorous
exposition. While lens MTF fall-off is certainly not the same shape as an
anti-alias filter, it varies in shape between different lenses and at
different zoom and aperture settings. Indeed, a "9 MP lens" would be even
less likely to benefit from an anti-alias filter on a 36 MP sensor.

BTW: I was /not/ intending to use a 2:1 linear, and 4:1 area comparison,
so the maths is correct. Poor lenses need less AA filtering, and the
degradation from an AA filter will be less with such lenses.

It begs the question: why would anyone buy a very high resolution sensor,
and yet use lower quality lenses? I can think of one answer - supposing
you were buying in the NEX range. You may want the features of the NEX-7,
but may not need the resolution, and you may be content with the smaller,
lighter, cheaper and lower-quality lenses. Because you want the features
of that particular model, you are stuck with the higher-resolution sensor
it comes with.

Cheers,
David T

"David J Taylor" wrote:
"David J. Littleboy" wrote in message
...
[]
- if you use lenses with no significant response above the Nyquist
frequency, then there's nothing for the AA filter to remove. I.e. with
lenses which aren't the sharpest it doesn't matter. Put another way, if
the camera is 36 MP but the lens only 18 MP, there may be no need for AA
filtering.

Bad idea, bad math. Sure, AA filters are a kludge (they shift (double)
the image in two directions), but they are still a much closer
approximation to a brick wall filter than lens infelicities, or even
diffraction. AA filters leave very good contrast in place at just a small
fraction of Nyquist below said frequency, which means that pretty much
all detail that can be correctly rendered actually is*. Lens resolution
falloff is gradual, so if you have a lens bad enough that it doesn't
cause aliasing, then it's going to have uninspired contrast at 1/2
Nyquist. So your 36MP camera is acting as a poor 9MP camera if your lens
is bad enough to not have aliasing problems.

*: In real life, Bayer images look really really good. The idea that
there's a problem is really quite silly.

David,

Please note the words "may be". Yes, of course it depends on the absolute
lens MTF etc., and it was obviously not intended to be a rigorous
exposition.

Rigor isn't the problem: the idea is _in principle_ wrong. For very good,
but easily explained informally, reasons: gradual falloff vs. sharp falloff.

While lens MTF fall-off is certainly not the same shape as an anti-alias
filter, it varies in shape between different lenses and at different zoom
and aperture settings.

Not really. Even poor lenses have long tails of low response out to quite
high frequencies.

--
David J. Littleboy
Tokyo, Japan

Rigor isn't the problem: the idea is _in principle_ wrong. For very
good, but easily explained informally, reasons: gradual falloff vs.
sharp falloff.

While lens MTF fall-off is certainly not the same shape as an
anti-alias filter, it varies in shape between different lenses and at
different zoom and aperture settings.

Not really. Even poor lenses have long tails of low response out to
quite high frequencies.

--
David J. Littleboy

If the response of the lens is low, then the amount of aliasing visible in
the final image will be low as well, and it follows that poorer lenses
have less need of a strong anti-alias filter then good lenses. It's the
net MTF above Nyquist which matters.

Having said that I, for one, would not be choosing a camera with no
anti-alias filter.

Cheers,
David

"David J. Littleboy" wrote in
:


"David J Taylor" wrote:
"Tim Conway" wrote in message
...

"Rich" wrote in message
...
To see (if the rumours are right) which model sells more, the one
with an
AA filter and the one without. If enough of the ones without sell,
this will be a radical change in cameras.

Not to open a can of worms here, but isn't anti-aliasing a good
thing? Even with a slight decrease in sharpness, I'd think it would
be beneficial.

Yes, of course it is, but:

- if you use lenses with no significant response above the Nyquist
frequency, then there's nothing for the AA filter to remove. I.e.
with lenses which aren't the sharpest it doesn't matter. Put another
way, if the camera is 36 MP but the lens only 18 MP, there may be no
need for AA filtering.

Bad idea, bad math. Sure, AA filters are a kludge (they shift (double)
the image in two directions), but they are still a much closer
approximation to a brick wall filter than lens infelicities, or even
diffraction. AA filters leave very good contrast in place at just a
small fraction of Nyquist below said frequency, which means that
pretty much all detail that can be correctly rendered actually is*.
Lens resolution falloff is gradual, so if you have a lens bad enough
that it doesn't cause aliasing, then it's going to have uninspired
contrast at 1/2 Nyquist. So your 36MP camera is acting as a poor 9MP
camera if your lens is bad enough to not have aliasing problems.

*: In real life, Bayer images look really really good. The idea that
there's a problem is really quite silly.


Only a problem is loss of resolution, which IS visible, even with a D200
as conversion of said camera proved that. I want to see the results of
this new AA-less camera versus the AA camera with a good lens. For those
terrified of the potential for interference with fine, repeating details,
they should stick with the AA filter.

"Rich" wrote in message
...
[]
Only a problem is loss of resolution, which IS visible, even with a D200
as conversion of said camera proved that. I want to see the results of
this new AA-less camera versus the AA camera with a good lens. For
those
terrified of the potential for interference with fine, repeating
details,
they should stick with the AA filter.

Noticeable resolution drop is perhaps not surprising on a 10 MP camera,
but I thought we were talking nearer 36 MP?

David