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So how good is 36 megapixels?



 
 
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  #21  
Old March 18th 13, 03:15 PM posted to rec.photo.digital.slr-systems
Doug McDonald[_6_]
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Posts: 157
Default So how good is 36 megapixels?



Please you could point to a sample image? What does it look like zoomed
right in to 1:1 viewing? I wonder whether the moiré may be due to
resampling for your display?



I can easily get moire when using photoshop at other than 100% view also.
Proves nothing about the camera though.

Trevor.


I have the pictures. No, I', not so stupid as to not check for moire at
100% or 200% view. They are absolutely hilarious. Of course. I did say LCD TV. And oh yes, I did use
my cheapest lens (50 mm f/1.7, at f/4.5),
but the moire is visible with my 24-105mm f/4L zoom, just not as horrific. Pics posted tomorrow on
Dropbox, I can't do that from home.

Doug McDonald



OK, I've posted the seriously moired pictures from a Canon 7D photographing
"Cupcake Wars" on FoodTV network on an LED TV. This used a Canon 50 mm f/1.7 lens at
either f/4.5 or f/5.6, if you care, look at the EXIF. There are two scenes,
the version beginning in an underscore was "developed" from raw with Digital Photo Professional
and is full frame. The ones beginning with A are developed with Photoshop and are
cropped quite a bit. Be sure to view them blown up to at least 100% or 200%. The ones
done in Photoshop have very low sharpening done to them.

https://dl.dropbox.com/u/5310360/_MG_3388.JPG
https://dl.dropbox.com/u/5310360/_MG_3391.JPG
https://dl.dropbox.com/u/5310360/AMG_3388.jpg
https://dl.dropbox.com/u/5310360/AMG_3390.jpg

Note that the distance to the screen is very critical to get the full
disastrous moire effect, as is focus. I focused using the Live View.
The camera was on a tripod.

Amazing, isn't it! These pictures are truly unusable.

YET ... I've never photographed a real scene, even with that or my even better
100mm f/2.8 Macro lens where I saw any problem at all.

People here have asked for moired pictures ... here they are!

Doug McDonald


  #22  
Old March 18th 13, 03:18 PM posted to rec.photo.digital.slr-systems
Doug McDonald[_6_]
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Posts: 157
Default So how good is 36 megapixels?

On 3/17/2013 9:25 PM, Doug McDonald wrote:



I have the pictures. No, I', not so stupid as to not check for moire at
100% or 200% view. They are absolutely hilarious.


One more comment: what is even more hilarious, if you look closely,
are the truly horrendous, disastrous, amazingly ugly, MPEG artifacts
introduced into the TV image by, presumably, Comcast. Look for the
amazing bad blocking. Yes, this is visible watching TV.

Doug McDonald

  #23  
Old March 19th 13, 12:56 AM posted to rec.photo.digital.slr-systems
Alan Browne
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Posts: 12,640
Default So how good is 36 megapixels?

On 2013.03.18 10:15 , Doug McDonald wrote:


Please you could point to a sample image? What does it look like

zoomed
right in to 1:1 viewing? I wonder whether the moiré may be due to
resampling for your display?


I can easily get moire when using photoshop at other than 100% view

also.
Proves nothing about the camera though.

Trevor.


I have the pictures. No, I', not so stupid as to not check for moire at
100% or 200% view. They are absolutely hilarious. Of course. I did

say LCD TV. And oh yes, I did use
my cheapest lens (50 mm f/1.7, at f/4.5),
but the moire is visible with my 24-105mm f/4L zoom, just not as

horrific. Pics posted tomorrow on
Dropbox, I can't do that from home.

Doug McDonald



OK, I've posted the seriously moired pictures from a Canon 7D photographing
"Cupcake Wars" on FoodTV network on an LED TV. This used a Canon 50 mm
f/1.7 lens at
either f/4.5 or f/5.6, if you care, look at the EXIF. There are two scenes,
the version beginning in an underscore was "developed" from raw with
Digital Photo Professional
and is full frame. The ones beginning with A are developed with
Photoshop and are
cropped quite a bit. Be sure to view them blown up to at least 100% or
200%. The ones
done in Photoshop have very low sharpening done to them.

https://dl.dropbox.com/u/5310360/_MG_3388.JPG
https://dl.dropbox.com/u/5310360/_MG_3391.JPG
https://dl.dropbox.com/u/5310360/AMG_3388.jpg
https://dl.dropbox.com/u/5310360/AMG_3390.jpg

Note that the distance to the screen is very critical to get the full
disastrous moire effect, as is focus. I focused using the Live View.
The camera was on a tripod.

Amazing, isn't it! These pictures are truly unusable.

YET ... I've never photographed a real scene, even with that or my even
better
100mm f/2.8 Macro lens where I saw any problem at all.

People here have asked for moired pictures ... here they are!


Your moiré effects have absolutely nothing to do with the pass frequency
of the lens and sensor. Indeed the smaller individual pixels of your
television are well resolved - your AA filter let them through unscathed
(or hardly scathed).

You're just getting "beats" of the line freq. of your sensor and the
line frequency of your television set - compounded by the "rgb"
arrangement of the LCD screen and that of your camera. Like you said,
you had to find "the right distance" to get this to appear.

A sensor with half or double the resolution would still moiré in this
fashion - just a different beat freq.

You probably compounded it by shooting on a 1080p screen with a 720 i/p
source signal...

You can get this by shooting through a screen at the right distance as
well...

I just did a quick test with my television and camera and while I get
some moiré it is not as severe as your examples. I didn't "work it" to
get hard moiré. (and I used a 50mm f/1.7 as well - but a plasma screen
and FF sensor (with AA filter)). I also used a blu-ray video (1080p) to
remove under-sampled video effects.

Go get us some moiré with a non "screened" scene.

--
"There were, unfortunately, no great principles on which parties
were divided – politics became a mere struggle for office."
-Sir John A. Macdonald

  #24  
Old March 19th 13, 01:09 AM posted to rec.photo.digital.slr-systems
Doug McDonald[_8_]
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Posts: 20
Default So how good is 36 megapixels?

On 3/18/2013 6:56 PM, Alan Browne wrote:
Your moiré effects have absolutely nothing to do with the pass frequency
of the lens and sensor.


Of course it does! If the AA filter blurred bigger than three pixels
there would be no moire. Its three because of the way a Bayer
sensor works. If a monochrome camera, it would be two.



Indeed the smaller individual pixels of your
television are well resolved - your AA filter let them through unscathed
(or hardly scathed).

Exactly!! The AA filter is inadequate to prevent moire.



You're just getting "beats" of the line freq. of your sensor and the
line frequency of your television set - compounded by the "rgb"
arrangement of the LCD screen and that of your camera. Like you said,
you had to find "the right distance" to get this to appear.


EXACTLY!!! That's the whole idea of moire.


A sensor with half or double the resolution would still moiré in this
fashion - just a different beat freq.

You probably compounded it by shooting on a 1080p screen with a 720 i/p
source signal...

No, it was 1080i. However, that would make no difference ... its the
arrangement of the RGB spots on the screen.


You can get this by shooting through a screen at the right distance as
well...


Exactly! That's the idea of moire!


I just did a quick test with my television and camera and while I get
some moiré it is not as severe as your examples. I didn't "work it" to
get hard moiré. (and I used a 50mm f/1.7 as well - but a plasma screen
and FF sensor (with AA filter)). I also used a blu-ray video (1080p) to
remove under-sampled video effects.

Go get us some moiré with a non "screened" scene.

As I said ... I never have seen any. And I've looked for it with bricks,
though not very hard.

I posted this because I was truly amazed at how bad it was. For normal
scenes its a non-issue.

Doug McDonald
  #25  
Old March 19th 13, 05:30 AM posted to rec.photo.digital.slr-systems
Trevor[_2_]
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Posts: 874
Default So how good is 36 megapixels?


"Me" wrote in message
...
On 18/03/2013 2:42 p.m., Trevor wrote:
"Me" wrote in message
...
36 mp is NOT 50% greater resolution than 24mp - linear resolution should
be used, in which case the difference is about 22%.

If you think you can see the difference in result between a 10mp camera
and an 11mp camera, then that's about the average difference in practice
you'd see between say a d600 and a d800.


The mathematics proving no conflict between those two statements evades
me.
Can you spell it out more clearly?


There's a slight mistake in what I said above, should read "10 and 11mp
image".

The rest is easy. DXO claim that with the very best lens they have tested
(IIRC the 85mm f1.4 G), the perceptual resolution in megapixels is about
22mp with a D800, and 19mp with a D3x. The worse the lens, the less the
difference.
If you need a definition of "perceptual megapixels" then I suggest you
visit DXO's site.


No, but you stated a 22% linear resolution difference above, so the
assumption of a 19/22 perceptual difference is a new claim, and totally
subjective of course.
The "perceptual difference" between a 10mp and 11mp image would still be
less than between a 24mp and 36mp image using the same half decent lens
however, despite you claim.


Don't forget that "perception /is/ reality".


Only one persons reality though.

Trevor.


  #26  
Old March 20th 13, 10:33 PM posted to rec.photo.digital.slr-systems
Alan Browne
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Posts: 12,640
Default So how good is 36 megapixels?

On 2013.03.18 20:09 , Doug McDonald wrote:

I posted this because I was truly amazed at how bad it was. For normal
scenes its a non-issue.


Recall that you put up these images to refute the idea that lenses at
some point can't deliver detail to the ever increasing density of sensors.

In reply to me stating that lenses behaved as spatial f filters as
sensor densities got higher,

You said: "Absurd: I own an 18 mpixel Canon7D, a crop frame
camera: and it shows bad moire on subjects like an LCD
TV. And it has an AA filter."

Your photos only illustrate a grid interference pattern. Nothing to to
at all with decreased resolution due to a lens and high sensor
densities. Nothing to do with AA filters either, to put a point on it.


--
"There were, unfortunately, no great principles on which parties
were divided – politics became a mere struggle for office."
-Sir John A. Macdonald


  #27  
Old March 21st 13, 12:17 AM posted to rec.photo.digital.slr-systems
Doug McDonald[_8_]
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Posts: 20
Default So how good is 36 megapixels?

On 3/20/2013 4:33 PM, Alan Browne wrote: On 2013.03.18 20:09 , Doug
McDonald wrote:

I posted this because I was truly amazed at how bad it was. For normal
scenes its a non-issue.


Recall that you put up these images to refute the idea that lenses at
some point can't deliver detail to the ever increasing density of

sensors.

In reply to me stating that lenses behaved as spatial f filters as
sensor densities got higher,

You said: "Absurd: I own an 18 mpixel Canon7D, a crop frame
camera: and it shows bad moire on subjects like an LCD
TV. And it has an AA filter."

Your photos only illustrate a grid interference pattern. Nothing to to
at all with decreased resolution due to a lens and high sensor
densities. Nothing to do with AA filters either, to put a point on it.


You are wrong. Moire IS a "grid interference pattern". The frequency of
the patterns in this instance are those of the sensor (the green
spacing) and the spacing of the individual RGB pixels (i.e. three camera
pixels to one RGB triple).

The pictures show CONCLUSIVELY that the lens is fully adequate to
resolve adjacent pixels, and that the AA filer is NOT seriously smearing
out the image enough to stop moire.

If the lens were blurring worse than the pixel pith, or there
were an agressive AA filter, THER WOULD BE NO OR MUCH LESS MOIRE.
In fact, exactly that starts happening at f/11 and the moire is almost
gone at f/22.


Doug McDonald
  #28  
Old March 21st 13, 12:33 AM posted to rec.photo.digital.slr-systems
Wolfgang Weisselberg
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Posts: 5,285
Default So how good is 36 megapixels?

Trevor wrote:

I can easily get moire when using photoshop at other than 100% view also.
Proves nothing about the camera though.


Proves that photoshop is incompetent at resampling for display.

-Wolfgang
  #29  
Old March 21st 13, 12:34 AM posted to rec.photo.digital.slr-systems
Alan Browne
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Posts: 12,640
Default So how good is 36 megapixels?

On 2013.03.20 19:17 , Doug McDonald wrote:
On 3/20/2013 4:33 PM, Alan Browne wrote: On 2013.03.18 20:09 , Doug
McDonald wrote:

I posted this because I was truly amazed at how bad it was. For normal
scenes its a non-issue.


Recall that you put up these images to refute the idea that lenses at
some point can't deliver detail to the ever increasing density of

sensors.

In reply to me stating that lenses behaved as spatial f filters as
sensor densities got higher,

You said: "Absurd: I own an 18 mpixel Canon7D, a crop frame
camera: and it shows bad moire on subjects like an LCD
TV. And it has an AA filter."

Your photos only illustrate a grid interference pattern. Nothing to to
at all with decreased resolution due to a lens and high sensor
densities. Nothing to do with AA filters either, to put a point on it.


You are wrong. Moire IS a "grid interference pattern". The frequency of


No **** Sherlock.

You're completely ignoring the point about lens _MTF_ which is what I
referred to before your "absurd" statement.

the patterns in this instance are those of the sensor (the green
spacing) and the spacing of the individual RGB pixels (i.e. three camera
pixels to one RGB triple).


Yes - as I clearly stated a couple posts ago - and still having NOTHING
TO DO with MTF which will soften detail to the pixel level as pixel
densities go up.

That is _WHY_ the DXO test referenced by the poster ("Me") showed LESS
resolution gain than pixel counts themselves would indicate.


The pictures show CONCLUSIVELY that the lens is fully adequate to
resolve adjacent pixels, and that the AA filer is NOT seriously smearing
out the image enough to stop moire.


If the AA smeared it enough to remove the moiré that you captured in
your contrivation, then you would be just as happy with the detail of a
6 Mpix camera. Probably not even then.


--
"There were, unfortunately, no great principles on which parties
were divided – politics became a mere struggle for office."
-Sir John A. Macdonald

  #30  
Old March 21st 13, 12:39 AM posted to rec.photo.digital.slr-systems
Wolfgang Weisselberg
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Posts: 5,285
Default So how good is 36 megapixels?

Trevor wrote:

No, it also depends on how much improvement can be made in lens design, or
it's just a number for the sake of a number. Sensor design is already
outstripping lens capability,


For mobile phone 41 MPix sensors, yes.
For the tele end of superzoom 16 M Pix cameras, yes.
For some kit lenses, especially outside their best
performance, yes.

For quality lenses used maximizing their capability? Where is
that XXX-Mpix or XXXX-MPix sensor you're talking about used
in commercial FF DSLRs?

-Wolfgang
 




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