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Why do I get purple fringes ?

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Anonymous
December 7, 2004 11:21:35 AM

Archived from groups: rec.photo.digital (More info?)

I was wondering if anyone could tell me why I am getting purple
fringes on a picture - or even better, how to stop it ! I took a
photo outside with the camera (fuji f610) on a tripod. Just to the
left of stright ahead is a house about 30 metres away. The windows of
the house all have come out with very noticable purple fringes down
the left side of the window frames (which are white). The camera was
set to auto exposure, it took the shot at 1/10 sec shutter, ISO 200
and 6MP resolution. Don't know if it has any bearing but the weather
was very cloudy grey and not very bright.

Any help would be much appreciated.

Many Thanks,
Trevor.

More about : purple fringes

Anonymous
December 7, 2004 12:26:09 PM

Archived from groups: rec.photo.digital (More info?)

nearly correct. Its the sensor, and the sensor alone

composition is the best cure ie prevention!


Phil Wheeler wrote:
> Use Google and search on Chromatic Abberation.
>
> You can reduce it by composition (avoiding high contrast areas) and
> remove it by post processing.
>
> Depending on the camera, it can be caused by the lens (CA) or the
sensor
> (blooming).
>
> Phil
>
> Trevor Davies wrote:
> > I was wondering if anyone could tell me why I am getting purple
> > fringes on a picture - or even better, how to stop it ! I took a
> > photo outside with the camera (fuji f610) on a tripod. Just to the
> > left of stright ahead is a house about 30 metres away. The windows
of
> > the house all have come out with very noticable purple fringes down
> > the left side of the window frames (which are white). The camera
was
> > set to auto exposure, it took the shot at 1/10 sec shutter, ISO 200
> > and 6MP resolution. Don't know if it has any bearing but the
weather
> > was very cloudy grey and not very bright.
> >
> > Any help would be much appreciated.
> >
> > Many Thanks,
> > Trevor.
Anonymous
December 7, 2004 12:26:25 PM

Archived from groups: rec.photo.digital (More info?)

nearly correct. Its the sensor, and the sensor alone

composition is the best cure ie prevention!


Phil Wheeler wrote:
> Use Google and search on Chromatic Abberation.
>
> You can reduce it by composition (avoiding high contrast areas) and
> remove it by post processing.
>
> Depending on the camera, it can be caused by the lens (CA) or the
sensor
> (blooming).
>
> Phil
>
> Trevor Davies wrote:
> > I was wondering if anyone could tell me why I am getting purple
> > fringes on a picture - or even better, how to stop it ! I took a
> > photo outside with the camera (fuji f610) on a tripod. Just to the
> > left of stright ahead is a house about 30 metres away. The windows
of
> > the house all have come out with very noticable purple fringes down
> > the left side of the window frames (which are white). The camera
was
> > set to auto exposure, it took the shot at 1/10 sec shutter, ISO 200
> > and 6MP resolution. Don't know if it has any bearing but the
weather
> > was very cloudy grey and not very bright.
> >
> > Any help would be much appreciated.
> >
> > Many Thanks,
> > Trevor.
Related resources
Anonymous
December 7, 2004 1:39:22 PM

Archived from groups: rec.photo.digital (More info?)

Hello Trevor,

I've noticed the same thing with pictures taken with my Nikon F100,
Nikkor 17-35mm 2.8 ED lens using Fuji Velvia 50. Then scanned via a
Minolta Dimage Scan Dual III. So in this case I don't the quality of
the lens had anything to do with creating purple fringes.

I found a Photoshop action that does a pretty decent job of removing
purple fringes. It worked on my scanned image and has worked on
pictures taken with the Nikon D100, 17-35, 35-70, and 80-200 2.8
lenses.

The website where you can read more bout this and download the free
action is at www.epaperpress.com/psphoto/
Then look under the table of contents and in the Preparation folder you
will see Purple Fringe.

Good luck and best regards,
German Rodriguez
www.pbase.com/germando


Jeremy wrote:
> "Marvin Margoshes" <physnospamchem@cloud9.net> wrote in message
> news:10rbrie8qtpcm41@corp.supernews.com...
> >
> > "Trevor Davies" <trevord70@hotmail.com> wrote in message
> > news:e3dea682.0412070821.3186a9c0@posting.google.com...
> > >I was wondering if anyone could tell me why I am getting purple
> > > fringes on a picture - or even better, how to stop it ! I took a
> > > photo outside with the camera (fuji f610) on a tripod. Just to
the
> > > left of stright ahead is a house about 30 metres away. The
windows of
> > > the house all have come out with very noticable purple fringes
down
> > > the left side of the window frames (which are white). The camera
was
> > > set to auto exposure, it took the shot at 1/10 sec shutter, ISO
200
> > > and 6MP resolution. Don't know if it has any bearing but the
weather
> > > was very cloudy grey and not very bright.
> > >
> > > Any help would be much appreciated.
> > >
> > > Many Thanks,
> > > Trevor.
> >
> > There isn't a simple, straightforward answer that I know of. I had
an Oly
> > 3030, a camera that many people complained had a purple fringe
problem. I
> > looked carefully at images that were likely to show the effect, and
> couldn't
> > find it. Perhaps there was some difference in the lens, the
sensor, or
> the
> > software in my camera.
> >
> >
>
> It is Chromatic Aberration, and it results from the optical property
of
> light of different colors tending to focus at slightly different
planes from
> the exact point of the film (or sensor) plane.
>
> It is typically at its worst on long zoom lenses. Some manufacturers
(Nikon
> especially) use extra low dispersion glass elements in some of their
long
> lenses to minimize this problem. Previously, some manufacturers used
> fluorite elements, rather than glass ones, but fluorite elements
tended to
> be expensive and were easily shattered.
>
> If your lens exhibits this fault, I am unaware of anything you can do
to
> minimize it (you might see if the effect is less pronounced if you
don't
> rack out the zoom as much). There is no filter that will correct
this
> problem.
>
> I purchased a camera with a 3x zoom as my way of steering clear of
this
> problem. Some manufacturers use better lenses than others. If your
camera
> does not have interchangeable lenses, the only way to get rid of the
problem
> is to replace the camera with a better model.
>
> There is more to the quality of the image than simply the number of
> megapixels . . .
Anonymous
December 7, 2004 1:39:51 PM

Archived from groups: rec.photo.digital (More info?)

Hello Trevor,

I've noticed the same thing with pictures taken with my Nikon F100,
Nikkor 17-35mm 2.8 ED lens using Fuji Velvia 50. Then scanned via a
Minolta Dimage Scan Dual III. So in this case I don't the quality of
the lens had anything to do with creating purple fringes.

I found a Photoshop action that does a pretty decent job of removing
purple fringes. It worked on my scanned image and has worked on
pictures taken with the Nikon D100, 17-35, 35-70, and 80-200 2.8
lenses.

The website where you can read more bout this and download the free
action is at www.epaperpress.com/psphoto/
Then look under the table of contents and in the Preparation folder you
will see Purple Fringe.

Good luck and best regards,
German Rodriguez
www.pbase.com/germando


Jeremy wrote:
> "Marvin Margoshes" <physnospamchem@cloud9.net> wrote in message
> news:10rbrie8qtpcm41@corp.supernews.com...
> >
> > "Trevor Davies" <trevord70@hotmail.com> wrote in message
> > news:e3dea682.0412070821.3186a9c0@posting.google.com...
> > >I was wondering if anyone could tell me why I am getting purple
> > > fringes on a picture - or even better, how to stop it ! I took a
> > > photo outside with the camera (fuji f610) on a tripod. Just to
the
> > > left of stright ahead is a house about 30 metres away. The
windows of
> > > the house all have come out with very noticable purple fringes
down
> > > the left side of the window frames (which are white). The camera
was
> > > set to auto exposure, it took the shot at 1/10 sec shutter, ISO
200
> > > and 6MP resolution. Don't know if it has any bearing but the
weather
> > > was very cloudy grey and not very bright.
> > >
> > > Any help would be much appreciated.
> > >
> > > Many Thanks,
> > > Trevor.
> >
> > There isn't a simple, straightforward answer that I know of. I had
an Oly
> > 3030, a camera that many people complained had a purple fringe
problem. I
> > looked carefully at images that were likely to show the effect, and
> couldn't
> > find it. Perhaps there was some difference in the lens, the
sensor, or
> the
> > software in my camera.
> >
> >
>
> It is Chromatic Aberration, and it results from the optical property
of
> light of different colors tending to focus at slightly different
planes from
> the exact point of the film (or sensor) plane.
>
> It is typically at its worst on long zoom lenses. Some manufacturers
(Nikon
> especially) use extra low dispersion glass elements in some of their
long
> lenses to minimize this problem. Previously, some manufacturers used
> fluorite elements, rather than glass ones, but fluorite elements
tended to
> be expensive and were easily shattered.
>
> If your lens exhibits this fault, I am unaware of anything you can do
to
> minimize it (you might see if the effect is less pronounced if you
don't
> rack out the zoom as much). There is no filter that will correct
this
> problem.
>
> I purchased a camera with a 3x zoom as my way of steering clear of
this
> problem. Some manufacturers use better lenses than others. If your
camera
> does not have interchangeable lenses, the only way to get rid of the
problem
> is to replace the camera with a better model.
>
> There is more to the quality of the image than simply the number of
> megapixels . . .
Anonymous
December 7, 2004 3:35:08 PM

Archived from groups: rec.photo.digital (More info?)

Trevor Davies wrote:
> I was wondering if anyone could tell me why I am getting purple
> fringes on a picture - or even better, how to stop it ! I took a
> photo outside with the camera (fuji f610) on a tripod. Just to the
> left of stright ahead is a house about 30 metres away. The windows of
> the house all have come out with very noticable purple fringes down
> the left side of the window frames (which are white). The camera was
> set to auto exposure, it took the shot at 1/10 sec shutter, ISO 200
> and 6MP resolution. Don't know if it has any bearing but the weather
> was very cloudy grey and not very bright.
>
> Any help would be much appreciated.
>
> Many Thanks,
> Trevor.
This is a fault of certain lens sets. Some are particularly bad about
this, others don't seem to have much of a problem.
Anonymous
December 7, 2004 3:54:25 PM

Archived from groups: rec.photo.digital (More info?)

"Trevor Davies" <trevord70@hotmail.com> wrote in message
news:e3dea682.0412070821.3186a9c0@posting.google.com...
>I was wondering if anyone could tell me why I am getting purple
> fringes on a picture - or even better, how to stop it ! I took a
> photo outside with the camera (fuji f610) on a tripod. Just to the
> left of stright ahead is a house about 30 metres away. The windows of
> the house all have come out with very noticable purple fringes down
> the left side of the window frames (which are white). The camera was
> set to auto exposure, it took the shot at 1/10 sec shutter, ISO 200
> and 6MP resolution. Don't know if it has any bearing but the weather
> was very cloudy grey and not very bright.
>
> Any help would be much appreciated.
>
> Many Thanks,
> Trevor.

There isn't a simple, straightforward answer that I know of. I had an Oly
3030, a camera that many people complained had a purple fringe problem. I
looked carefully at images that were likely to show the effect, and couldn't
find it. Perhaps there was some difference in the lens, the sensor, or the
software in my camera.
December 7, 2004 4:44:08 PM

Archived from groups: rec.photo.digital (More info?)

On 7 Dec 2004 09:26:09 -0800, digiboy@mailinator.com wrote:

>nearly correct. Its the sensor, and the sensor alone

No it isn't. CA is a function of the lens. On some Canon products
you can get CA from the sensor, but that is only because the sensor
uses "microlenses" over each receptor.


Drifter
"I've been here, I've been there..."
Anonymous
December 7, 2004 4:44:09 PM

Archived from groups: rec.photo.digital (More info?)

"Drifter" <zespectre@askme.com> wrote in message
news:D 9ubr012v45hp0k6hlklf9vcn6bffpoiu5@4ax.com...
> On 7 Dec 2004 09:26:09 -0800, digiboy@mailinator.com wrote:
>
> >nearly correct. Its the sensor, and the sensor alone
>
> No it isn't. CA is a function of the lens. On some Canon products
> you can get CA from the sensor, but that is only because the sensor
> uses "microlenses" over each receptor.

If it were true chromatic aberration, there would be a spectrum of colors,
not just a tight band centered about purple. If it were true chromatic
aberration, then the effect would be present regardless of contrast, whereas
purple fringing seems to occur solely the transitions between very dark and
very light areas. Blooming caused by electron spill-over from the
quantum-well photosites on the sensor seems the more likely culprit,
exacerbated by in-camera sharpening software, perhaps.
Anonymous
December 7, 2004 7:27:41 PM

Archived from groups: rec.photo.digital (More info?)

Use Google and search on Chromatic Abberation.

You can reduce it by composition (avoiding high contrast areas) and
remove it by post processing.

Depending on the camera, it can be caused by the lens (CA) or the sensor
(blooming).

Phil

Trevor Davies wrote:
> I was wondering if anyone could tell me why I am getting purple
> fringes on a picture - or even better, how to stop it ! I took a
> photo outside with the camera (fuji f610) on a tripod. Just to the
> left of stright ahead is a house about 30 metres away. The windows of
> the house all have come out with very noticable purple fringes down
> the left side of the window frames (which are white). The camera was
> set to auto exposure, it took the shot at 1/10 sec shutter, ISO 200
> and 6MP resolution. Don't know if it has any bearing but the weather
> was very cloudy grey and not very bright.
>
> Any help would be much appreciated.
>
> Many Thanks,
> Trevor.
December 7, 2004 9:11:51 PM

Archived from groups: rec.photo.digital (More info?)

"Marvin Margoshes" <physnospamchem@cloud9.net> wrote in message
news:10rbrie8qtpcm41@corp.supernews.com...
>
> "Trevor Davies" <trevord70@hotmail.com> wrote in message
> news:e3dea682.0412070821.3186a9c0@posting.google.com...
> >I was wondering if anyone could tell me why I am getting purple
> > fringes on a picture - or even better, how to stop it ! I took a
> > photo outside with the camera (fuji f610) on a tripod. Just to the
> > left of stright ahead is a house about 30 metres away. The windows of
> > the house all have come out with very noticable purple fringes down
> > the left side of the window frames (which are white). The camera was
> > set to auto exposure, it took the shot at 1/10 sec shutter, ISO 200
> > and 6MP resolution. Don't know if it has any bearing but the weather
> > was very cloudy grey and not very bright.
> >
> > Any help would be much appreciated.
> >
> > Many Thanks,
> > Trevor.
>
> There isn't a simple, straightforward answer that I know of. I had an Oly
> 3030, a camera that many people complained had a purple fringe problem. I
> looked carefully at images that were likely to show the effect, and
couldn't
> find it. Perhaps there was some difference in the lens, the sensor, or
the
> software in my camera.
>
>

It is Chromatic Aberration, and it results from the optical property of
light of different colors tending to focus at slightly different planes from
the exact point of the film (or sensor) plane.

It is typically at its worst on long zoom lenses. Some manufacturers (Nikon
especially) use extra low dispersion glass elements in some of their long
lenses to minimize this problem. Previously, some manufacturers used
fluorite elements, rather than glass ones, but fluorite elements tended to
be expensive and were easily shattered.

If your lens exhibits this fault, I am unaware of anything you can do to
minimize it (you might see if the effect is less pronounced if you don't
rack out the zoom as much). There is no filter that will correct this
problem.

I purchased a camera with a 3x zoom as my way of steering clear of this
problem. Some manufacturers use better lenses than others. If your camera
does not have interchangeable lenses, the only way to get rid of the problem
is to replace the camera with a better model.

There is more to the quality of the image than simply the number of
megapixels . . .
Anonymous
December 7, 2004 11:02:04 PM

Archived from groups: rec.photo.digital (More info?)

trevord70@hotmail.com (Trevor Davies) wrote in
news:e3dea682.0412070821.3186a9c0@posting.google.com:

> I was wondering if anyone could tell me why I am getting purple
> fringes on a picture - or even better, how to stop it ! I took a
> photo outside with the camera (fuji f610) on a tripod. Just to the
> left of stright ahead is a house about 30 metres away. The windows of
> the house all have come out with very noticable purple fringes down
> the left side of the window frames (which are white). The camera was
> set to auto exposure, it took the shot at 1/10 sec shutter, ISO 200
> and 6MP resolution. Don't know if it has any bearing but the weather
> was very cloudy grey and not very bright.
>

You have got some different answers regarding the cause,
as always when this topic comes up :) 

The easiest cure (if you cant avoid large contrast in
the picture, particularly in the corners) is to desaturate
purple. It is more efficient than one can imagine.

Depending on your photo editor you can select purple
using several methods. No matter how you do it, just
desaturate the selection.


/Roland
Anonymous
December 8, 2004 12:05:06 AM

Archived from groups: rec.photo.digital (More info?)

Paul H. wrote:
> "Drifter" <zespectre@askme.com> wrote in message
> news:D 9ubr012v45hp0k6hlklf9vcn6bffpoiu5@4ax.com...
>
>>On 7 Dec 2004 09:26:09 -0800, digiboy@mailinator.com wrote:
>>
>>
>>>nearly correct. Its the sensor, and the sensor alone
>>
>>No it isn't. CA is a function of the lens. On some Canon products
>>you can get CA from the sensor, but that is only because the sensor
>>uses "microlenses" over each receptor.
>
>
> If it were true chromatic aberration, there would be a spectrum of colors,
> not just a tight band centered about purple.

To quote:

""Purple fringing" is the most common type of chromatic aberration in
digital cameras."

Source is:

http://www.dpreview.com/learn/?/Glossary/Optical/Chroma...

Phil
Anonymous
December 8, 2004 12:05:07 AM

Archived from groups: rec.photo.digital (More info?)

"Phil Wheeler" <w6tuh-ng5@yahoo.com> wrote in message
news:6Wotd.3951$Ew6.1269@twister.socal.rr.com...
>
>
> Paul H. wrote:
> > "Drifter" <zespectre@askme.com> wrote in message
> > news:D 9ubr012v45hp0k6hlklf9vcn6bffpoiu5@4ax.com...
> >
> >>On 7 Dec 2004 09:26:09 -0800, digiboy@mailinator.com wrote:
> >>
> >>
> >>>nearly correct. Its the sensor, and the sensor alone
> >>
> >>No it isn't. CA is a function of the lens. On some Canon products
> >>you can get CA from the sensor, but that is only because the sensor
> >>uses "microlenses" over each receptor.
> >
> >
> > If it were true chromatic aberration, there would be a spectrum of
colors,
> > not just a tight band centered about purple.
>
> To quote:
>
> ""Purple fringing" is the most common type of chromatic aberration in
> digital cameras."
>
> Source is:
>
>
http://www.dpreview.com/learn/?/Glossary/Optical/Chroma...
>
> Phil

And just what does *that* prove? Purpling fringing is a "chromatic
aberration" only in the sense that it's chromatic (colored) and an
aberration (something deviating from normality) but that's merely a
semantic coincidence, not a technical definition. In the centuries before
digital cameras AND dpreview came along, however, the technical phrase
"chromatic aberration" referred *specifically* to color fringing/distortion
caused by light-dispersive elements in an optical system and as far as I'm
concerned that definition still obtains. If someone chooses to re-define
the term to describe some other phenomenon, that's not my problem and in any
case, merely bastardizing the definition does NOT change the underlying
physics of the matter.

And who appointed dpreview to tbe the official and final arbiter of
physics/optics/camera terminology, anyway? You cite an authority which has
been authorized by no one, except perhaps yourself. To quote:

--------------------------------------
Main Entry: chromatic aberration
Function: noun
: aberration caused by the differences in refraction of the colored rays of
the spectrum

Source: Merriam-Webster
---------------------------------------

....and "differences in refraction" describe, in optics, what is known as a
"dispersive" medium.
Anonymous
December 8, 2004 12:05:08 AM

Archived from groups: rec.photo.digital (More info?)

"Paul H." <xxpaulhtck@zzcomcast.yycom> a écrit dans le message de
news:mMCdnRs_-7vHuivcRVn-3A@comcast.com...
>
> "Phil Wheeler" <w6tuh-ng5@yahoo.com> wrote in message
> news:6Wotd.3951$Ew6.1269@twister.socal.rr.com...
> >
> >
> > Paul H. wrote:
> > > "Drifter" <zespectre@askme.com> wrote in message
> > > news:D 9ubr012v45hp0k6hlklf9vcn6bffpoiu5@4ax.com...
> > >
> > >>On 7 Dec 2004 09:26:09 -0800, digiboy@mailinator.com wrote:
> > >>
> > >>
> > >>>nearly correct. Its the sensor, and the sensor alone
> > >>
> > >>No it isn't. CA is a function of the lens. On some Canon products
> > >>you can get CA from the sensor, but that is only because the sensor
> > >>uses "microlenses" over each receptor.
> > >
> > >
> > > If it were true chromatic aberration, there would be a spectrum of
> colors,
> > > not just a tight band centered about purple.
> >
> > To quote:
> >
> > ""Purple fringing" is the most common type of chromatic aberration in
> > digital cameras."
> >
> > Source is:
> >
> >
>
http://www.dpreview.com/learn/?/Glossary/Optical/Chroma...
> >
> > Phil


>
> And who appointed dpreview to tbe the official and final arbiter of
> physics/optics/camera terminology, anyway? You cite an authority which
has
> been authorized by no one, except perhaps yourself. To quote:
>
> --------------------------------------
> Main Entry: chromatic aberration
> Function: noun
> : aberration caused by the differences in refraction of the colored rays
of
> the spectrum
>
> Source: Merriam-Webster
> ---------------------------------------
>
> ...and "differences in refraction" describe, in optics, what is known as a
> "dispersive" medium.
>

Please quit arguing.
Ask the guy if aberrations are purple on one side (corner) of the picture,
and another color in the opposite region.
This should make the point that the lens is the culprit.

mb
Anonymous
December 8, 2004 1:17:01 AM

Archived from groups: rec.photo.digital (More info?)

In article <1102440385.833247.45430@z14g2000cwz.googlegroups.com>,
digiboy@mailinator.com wrote:

> nearly correct. Its the sensor, and the sensor alone
>
> composition is the best cure ie prevention!

No, it's a combination of the lenses, the sensor microlenses, and the
steep angle of light hitting the sensor in compact cameras.

It can be reduced by changing the zoom and aperture. You have to
experiment to see what works.


>
> Phil Wheeler wrote:
> > Use Google and search on Chromatic Abberation.
> >
> > You can reduce it by composition (avoiding high contrast areas) and
> > remove it by post processing.
> >
> > Depending on the camera, it can be caused by the lens (CA) or the
> sensor
> > (blooming).
> >
> > Phil
> >
> > Trevor Davies wrote:
> > > I was wondering if anyone could tell me why I am getting purple
> > > fringes on a picture - or even better, how to stop it ! I took a
> > > photo outside with the camera (fuji f610) on a tripod. Just to the
> > > left of stright ahead is a house about 30 metres away. The windows
> of
> > > the house all have come out with very noticable purple fringes down
> > > the left side of the window frames (which are white). The camera
> was
> > > set to auto exposure, it took the shot at 1/10 sec shutter, ISO 200
> > > and 6MP resolution. Don't know if it has any bearing but the
> weather
> > > was very cloudy grey and not very bright.
> > >
> > > Any help would be much appreciated.
> > >
> > > Many Thanks,
> > > Trevor.
Anonymous
December 8, 2004 1:54:59 AM

Archived from groups: rec.photo.digital (More info?)

WOW....you must be having a bad hair day...lol I for one do not have
this problem as I've been shaving my head since I got out of the Marine
Corps when I was 25.

Such big words and I see you're pretty good at using Google to find a
definition by Merriam-Webster. To really show off and impress you
should have included the following:
-------------------------------------------------------------------------
Color distortion in an image produced by a lens, caused by the
inability of the lens to bring the various colors of light to focus at
a single point. Also called chromatism.

Source: The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by
Houghton Mifflin Company.
---------------------------------------------------------------------------
(Opt.) The convergence to different foci, by a lens or mirror, of rays
of light emanating from one and the same point, or the deviation of
such rays from a single focus; called spherical aberration, when due to
the spherical form of the lens or mirror, such form giving different
foci for central and marginal rays; and chromatic aberration, when due
to different refrangibilities of the colored rays of the spectrum,
those of each color having a distinct focus.

Source: Webster's Revised Unabridged Dictionary, © 1996, 1998 MICRA,
Inc.
--------------------------------------------------------------------
n : an optical aberration in which the image has colored fringes

Source: WordNet ® 2.0, © 2003 Princeton University
---------------------------------------------------------------

Just to name a few more sources. But I think he was asking for some
help and not the very impressive definition of chromatic aberration
"centuries before
digital cameras AND dpreview came along" which in of itself did not
supply a solution to his purple fringing.

And as for DPREVIEW, below is just a sampling of the type of
people/photographers that participate in the forums with very helpful
information. Have very informative websites and quote from or link back
to DPREVIEW on all types of product reviews. Many times DPREVIEW is one
of the FIRST to get a look and evaluate cameras from all the major
manufacturers.

Ron Reznick http://www.digital-images.net/index.html
Michael Reichmann http://luminous-landscape.com/
Rob Galbraith http://www.robgalbraith.com/bins/index.asp
Neil van Niekerk http://www.planetneil.com/index.html
Dan Heller http://www.danheller.com/

Below are just a few of the inconsequential publications that quote
from or reference DPREVIEW. Hmmmm.........I wonder

--------------------------
October 2004 - PC Magazine
Top 101 web sites: Fall 2004 (No. 1: Consumer Electronics & Photograph)

Trying to choose between two or three similar digital cameras? Here
you'll find reviews in which "thorough" is an understatement. They give
complete specs; go into intricate detail about performance; describe
every button, screen, knob, and setting; and provide numerous diagrams
and sample photos.
----------------------
October 2004 - The Wall Street Journal
The Myth of the Megapixel - Walt Mossberg

For more sound information on digital cameras, several Web sites
offer lots of good detail. Two of my favorites are Digital Photography
Review and the Digital Camera Resource Page. Both are worth consulting.

-------------------------
July 2004 - Forbes Best of The Web 2004
Forbes Best of The Web - Digital Photography

In the vast and cluttered world of digital cameras and accessories,
DP Review offers one of the most thorough, knowledgeable and up-to-date
sources of information. Browse the archive of more than 130 in-depth
camera reviews, complete with full descriptions and images. The review
of the Konica Minolta DiMAGE A2 includes 22 pages of large product
pictures, specifications, photographic tests and more
------------------------
August 2003 - CNN Money
How to buy a great digital camera

The newest digital camera models are more fun, more capable and,
for busy shooters, cheaper to use than film. Even by
consumer-electronic standards, digital models have dropped in price and
improved in quality at an impressive pace. Prices of some high-end
cameras are now a twentieth of the price of lesser models three years
ago...
....You can find help with comparison shopping at two Web sites
obsessively devoted to digital cameras, Digital Photography Review and
Digital Camera Resource.
----------------------
December 2002 - Wired News
Digital Cameras: Where to Start?

First, decide how much money you are willing to spend. Take into
account that you will need a computer to download and e-mail the images
and a printer -- if you want a hard copy of your pictures. Once you
figure out your budget, compare cameras within your desired price point
on Digital Photography Review -- a website highly recommended by
digital camera experts.
------------------------
February 2002 - Business 2.0
Say Cheese, You Poor Emulsion-Film Dinosaurs

....To understand the technological leap the X3 represents, listen
to Phil Askey, editor of digital photography site DPReview.com. On
April Fools' Day 2000, Askey posted a story saying that Canon (CAJ) was
working on a chip that would do what Foveon says its X3 does. It was a
hoax, but it generated heavy excitement on his chat boards before "the
real techie guys got on and said, 'It's just not possible to do that,'"
Askey says...
------------------------

To everyone else I apologize for this very lengthy post. Believe it or
not it's a first with regards to responding to someone who comes
across, what is the word...well you know. Enough said this is all I
have to say regarding Phil's response. Feel free to search my name in
the DPREVIEW forums and you'll see that I have NEVER responded in this
manner before.

Best regards,
German Rodriguez
www.pbase.com/germando
Anonymous
December 8, 2004 2:01:04 AM

Archived from groups: rec.photo.digital (More info?)

My post was directed to Paul H. as it appears my post fell under Phil
Wheeler instead.
It's a bit late and I'm off to bed.

Regards,
German
Anonymous
December 8, 2004 5:38:02 AM

Archived from groups: rec.photo.digital (More info?)

m.b. wrote:
> "Paul H." <xxpaulhtck@zzcomcast.yycom> a écrit dans le message de
> news:mMCdnRs_-7vHuivcRVn-3A@comcast.com...
>
>>"Phil Wheeler" <w6tuh-ng5@yahoo.com> wrote in message
>>news:6Wotd.3951$Ew6.1269@twister.socal.rr.com...
>>
>>>
>>>Paul H. wrote:
>>>
>>>>"Drifter" <zespectre@askme.com> wrote in message
>>>>news:D 9ubr012v45hp0k6hlklf9vcn6bffpoiu5@4ax.com...
>>>>
>>>>
>>>>>On 7 Dec 2004 09:26:09 -0800, digiboy@mailinator.com wrote:
>>>>>
>>>>>
>>>>>
>>>>>>nearly correct. Its the sensor, and the sensor alone
>>>>>
>>>>>No it isn't. CA is a function of the lens. On some Canon products
>>>>>you can get CA from the sensor, but that is only because the sensor
>>>>>uses "microlenses" over each receptor.
>>>>
>>>>
>>>>If it were true chromatic aberration, there would be a spectrum of
>>
>>colors,
>>
>>>>not just a tight band centered about purple.
>>>
>>>To quote:
>>>
>>>""Purple fringing" is the most common type of chromatic aberration in
>>>digital cameras."
>>>
>>>Source is:
>>>
>>>
>>
> http://www.dpreview.com/learn/?/Glossary/Optical/Chroma...
>
>>>Phil
>
>
>
>>And who appointed dpreview to tbe the official and final arbiter of
>>physics/optics/camera terminology, anyway? You cite an authority which
>
> has
>
>>been authorized by no one, except perhaps yourself. To quote:
>>
> Please quit arguing.

No argument .. since I know what I know.

The url I cited has an article (cited) by a fellow who wrote a book on
digital photography. I suspect he knows more about the subject than
most here.

Do I care? No .. just trying to provide what I think is useful info.
Paul can go read it or remain ignorant.

Phil
Anonymous
December 8, 2004 10:48:29 AM

Archived from groups: rec.photo.digital (More info?)

"m.b." <spamkiller@moon.net> wrote in message
news:Lgstd.22268$Ou1.1331369@weber.videotron.net...
>
> "Paul H." <xxpaulhtck@zzcomcast.yycom> a écrit dans le message de
> news:mMCdnRs_-7vHuivcRVn-3A@comcast.com...
> >
> > "Phil Wheeler" <w6tuh-ng5@yahoo.com> wrote in message
> > news:6Wotd.3951$Ew6.1269@twister.socal.rr.com...
> > >
> > >
> > > Paul H. wrote:
> > > > "Drifter" <zespectre@askme.com> wrote in message
> > > > news:D 9ubr012v45hp0k6hlklf9vcn6bffpoiu5@4ax.com...
> > > >
> > > >>On 7 Dec 2004 09:26:09 -0800, digiboy@mailinator.com wrote:
> > > >>
> > > >>
> > > >>>nearly correct. Its the sensor, and the sensor alone
> > > >>
> > > >>No it isn't. CA is a function of the lens. On some Canon products
> > > >>you can get CA from the sensor, but that is only because the sensor
> > > >>uses "microlenses" over each receptor.
> > > >
> > > >
> > > > If it were true chromatic aberration, there would be a spectrum of
> > colors,
> > > > not just a tight band centered about purple.
> > >
> > > To quote:
> > >
> > > ""Purple fringing" is the most common type of chromatic aberration in
> > > digital cameras."
> > >
> > > Source is:
> > >
> > >
> >
>
http://www.dpreview.com/learn/?/Glossary/Optical/Chroma...
> > >
> > > Phil
>
>
> >
> > And who appointed dpreview to tbe the official and final arbiter of
> > physics/optics/camera terminology, anyway? You cite an authority which
> has
> > been authorized by no one, except perhaps yourself. To quote:
> >
> > --------------------------------------
> > Main Entry: chromatic aberration
> > Function: noun
> > : aberration caused by the differences in refraction of the colored rays
> of
> > the spectrum
> >
> > Source: Merriam-Webster
> > ---------------------------------------
> >
> > ...and "differences in refraction" describe, in optics, what is known as
a
> > "dispersive" medium.
> >
>
> Please quit arguing.
> Ask the guy if aberrations are purple on one side (corner) of the picture,
> and another color in the opposite region.
> This should make the point that the lens is the culprit.
>
> mb
>
While the PF does tend to point a way from the center axis of the lens, It
could be an effect from the microlenses used on the sensor as the light rays
arriving at the corners may not be exactly parallel. That is, The light rays
tilt in from the center axis of the lens. This could cause excessive
dispersion from these off axis rays and could spill over to adjacent cells.
Remember from physics 101 that the violet (short wavelength) light is "bent"
the most.

Just my observation. A study of this is really needed.
bg
Anonymous
December 8, 2004 1:19:29 PM

Archived from groups: rec.photo.digital (More info?)

Phil Wheeler wrote:
[]
> Do I care? No .. just trying to provide what I think is useful info.
> Paul can go read it or remain ignorant.
>
> Phil

You may not care, but I do. Whilst purple-fringing has a similar
appearance to chromatic aberration in lenses, it does not have the same
underlying cause, and to describe it as "lens chromatic aberration" is
quite simply misleading.

Cheers,
David
Anonymous
December 8, 2004 4:09:19 PM

Archived from groups: rec.photo.digital (More info?)

On Wed, 8 Dec 2004 10:19:29 -0000, "David J Taylor"
<david-taylor@invalid.com> wrote:

>Phil Wheeler wrote:
>[]
>> Do I care? No .. just trying to provide what I think is useful info.
>> Paul can go read it or remain ignorant.
>>
>> Phil
>
>You may not care, but I do. Whilst purple-fringing has a similar
>appearance to chromatic aberration in lenses, it does not have the same
>underlying cause, and to describe it as "lens chromatic aberration" is
>quite simply misleading.

... not "misleading" .. just plainly wrong period. :-)
Anonymous
December 9, 2004 12:04:23 AM

Archived from groups: rec.photo.digital (More info?)

First go read the book, David -- then we can communicate.

David J Taylor wrote:

> Phil Wheeler wrote:
> []
>
>>Do I care? No .. just trying to provide what I think is useful info.
>>Paul can go read it or remain ignorant.
>>
>>Phil
>
>
> You may not care, but I do. Whilst purple-fringing has a similar
> appearance to chromatic aberration in lenses, it does not have the same
> underlying cause, and to describe it as "lens chromatic aberration" is
> quite simply misleading.
>
> Cheers,
> David
>
>
Anonymous
December 9, 2004 12:05:33 AM

Archived from groups: rec.photo.digital (More info?)

Read the book, pal .. then tell me if *it* is misleading.

Messages here tell little.

imbsysop wrote:
> On Wed, 8 Dec 2004 10:19:29 -0000, "David J Taylor"
> <david-taylor@invalid.com> wrote:
>
>
>>Phil Wheeler wrote:
>>[]
>>
>>>Do I care? No .. just trying to provide what I think is useful info.
>>>Paul can go read it or remain ignorant.
>>>
>>>Phil
>>
>>You may not care, but I do. Whilst purple-fringing has a similar
>>appearance to chromatic aberration in lenses, it does not have the same
>>underlying cause, and to describe it as "lens chromatic aberration" is
>>quite simply misleading.
>
>
> .. not "misleading" .. just plainly wrong period. :-)
>
Anonymous
December 9, 2004 12:07:56 AM

Archived from groups: rec.photo.digital (More info?)

Phil Wheeler wrote:
> First go read the book, David -- then we can communicate.
>
> David J Taylor wrote:

What's that supposed to mean? I point out that PF and CA don't have the
same underlying cause. Don't you agree with that?

David
Anonymous
December 9, 2004 2:01:49 PM

Archived from groups: rec.photo.digital (More info?)

On Wed, 08 Dec 2004 21:05:33 GMT, Phil Wheeler <w6tuh-ng5@yahoo.com>
wrote:

>Read the book, pal .. then tell me if *it* is misleading.
>
>Messages here tell little.
>

pal .. if the author is not able to differentiate CA and PF in origin
he should not be writing books in the first place .. that's what
messages here may tell you .. :-)
Anonymous
December 17, 2004 2:37:05 AM

Archived from groups: rec.photo.digital (More info?)

On Tue, 07 Dec 2004 18:11:51 GMT, "Jeremy" <jeremy@nospam.com> wrote:



>It is Chromatic Aberration, and it results from the optical property of
>light of different colors tending to focus at slightly different planes from
>the exact point of the film (or sensor) plane.
>
>It is typically at its worst on long zoom lenses. Some manufacturers (Nikon
>especially) use extra low dispersion glass elements in some of their long
>lenses to minimize this problem. Previously, some manufacturers used
>fluorite elements, rather than glass ones, but fluorite elements tended to
>be expensive and were easily shattered.
>
>If your lens exhibits this fault, I am unaware of anything you can do to
>minimize it (you might see if the effect is less pronounced if you don't
>rack out the zoom as much). There is no filter that will correct this
>problem.
>
>I purchased a camera with a 3x zoom as my way of steering clear of this
>problem. Some manufacturers use better lenses than others. If your camera
>does not have interchangeable lenses, the only way to get rid of the problem
>is to replace the camera with a better model.
>
>There is more to the quality of the image than simply the number of
>megapixels . . .
>
>


Two comments - first I hope I'm answering the proper poster. And
second I don't feel qualified to get into the argument whether it's
the lens or something else, but I have been closely involved in the
"low dispersion lens" field. Several years ago I did a lot of
searching for a really good spotting scope to attach to my digital
cameras. After trying MANY that were not up to the task, I tried a
Kowa that did NOT have the fluorite lenses, and it was also not
adequate. I considered the Kowa models with the fluorite lens, but
about then I was pointed to the Swarovski scopes with H.D. glass, and
bought one of those. It was the most expensive then available, but
I've never regretted it. NO fringing, NO chromatic aberration that
I've ever detected. ALL these tests with the same cameras, thus I
conclude that for MY purposes it was not the camera, but the long
range lenses!!! Take this for what you wish. (And I still do not
really know if the Swarovski uses fluorite lens or not, but it's the
best I found.)

Olin McDaniel
Anonymous
December 28, 2004 9:20:54 PM

Archived from groups: rec.photo.digital (More info?)

In message <PtidnWFVbvFUiivcRVn-vg@comcast.com>,
"Paul H." <xxpaulhtck@zzcomcast.yycom> wrote:

>"Drifter" <zespectre@askme.com> wrote in message
>news:D 9ubr012v45hp0k6hlklf9vcn6bffpoiu5@4ax.com...

>> No it isn't. CA is a function of the lens. On some Canon products
>> you can get CA from the sensor, but that is only because the sensor
>> uses "microlenses" over each receptor.

>If it were true chromatic aberration, there would be a spectrum of colors,
>not just a tight band centered about purple. If it were true chromatic
>aberration, then the effect would be present regardless of contrast, whereas
>purple fringing seems to occur solely the transitions between very dark and
>very light areas.

The OP did claim, however, that the effect was directional, implying
possible CA. Without seeing the image, however, all speculations are
weak.

>Blooming caused by electron spill-over from the
>quantum-well photosites on the sensor seems the more likely culprit,
>exacerbated by in-camera sharpening software, perhaps.

Another test would be to shoot at different ISOs. ISO should not affect
CA, but it will affect sensor saturation, as the saturation level of the
sensor is more stops away from average exposure at higher ISOs.
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
Anonymous
December 28, 2004 9:26:34 PM

Archived from groups: rec.photo.digital (More info?)

In message <6Wotd.3951$Ew6.1269@twister.socal.rr.com>,
Phil Wheeler <w6tuh-ng5@yahoo.com> wrote:

>To quote:
>
>""Purple fringing" is the most common type of chromatic aberration in
>digital cameras."
>
>Source is:
>
>http://www.dpreview.com/learn/?/Glossary/Optical/Chroma...

DPReview is wrong.

"Purple fringing" originally referred to sensor issues, and then people
later mis-applied it to CA.

Purple fringing from the sensor has nothing to do with chromatic issues;
it is an artifact of the Bayer CFA and the demosaicing process. On most
of the earlier cameras, the green channel was the most sensitive, so it
clipped first and bled over into the red and blue cells (which were not
saturated because of stronger color filters), increasing the balance of
red and blue (purple).
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
Anonymous
December 28, 2004 9:26:35 PM

Archived from groups: rec.photo.digital (More info?)

<JPS@no.komm> a écrit dans le message de
news:gs83t050ldupacgp0229v5v3erblq49sg1@4ax.com...
> In message <6Wotd.3951$Ew6.1269@twister.socal.rr.com>,
> Phil Wheeler <w6tuh-ng5@yahoo.com> wrote:
>
> >To quote:
> >
> >""Purple fringing" is the most common type of chromatic aberration in
> >digital cameras."
> >
> >Source is:
> >
>
>http://www.dpreview.com/learn/?/Glossary/Optical/Chroma...
tm
>
> DPReview is wrong.
>
> "Purple fringing" originally referred to sensor issues, and then people
> later mis-applied it to CA.
>
> Purple fringing from the sensor has nothing to do with chromatic issues;

Take one second to look at the dpreview example before teaching ex cathedra.
When cyan fringes are on only one side of the subject, or red fringes on the
opposite side, this is a true optical issue.

Produced mainly on long range cheap miracle zooms.

mb
Anonymous
December 28, 2004 9:29:09 PM

Archived from groups: rec.photo.digital (More info?)

In message <mMCdnRs_-7vHuivcRVn-3A@comcast.com>,
"Paul H." <xxpaulhtck@zzcomcast.yycom> wrote:

>And who appointed dpreview to tbe the official and final arbiter of
>physics/optics/camera terminology, anyway? You cite an authority which has
>been authorized by no one, except perhaps yourself. To quote:

Amen. DPReview is run by humans. DPReview is big, but big does not
equal correct. I get tired of people asking "can Phil Askey verify
that?", when he is clearly a mortal who has bitten off more than he can
chew.
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
Anonymous
December 28, 2004 9:32:11 PM

Archived from groups: rec.photo.digital (More info?)

In message <eOttd.3969$Ew6.3044@twister.socal.rr.com>,
Phil Wheeler <w6tuh-ng5@yahoo.com> wrote:

>I suspect he knows more about the subject than
>most here.

No; it means that he is more inclined to write a book.

Guess what? Publishers are not omniscient gods who know more than the
writers, and only allow people who really know what they're talking
about write. All books should be taken with a pound of salt, and
considered food for thought; not scripture.
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
Anonymous
December 28, 2004 9:37:34 PM

Archived from groups: rec.photo.digital (More info?)

In message <10rbrie8qtpcm41@corp.supernews.com>,
"Marvin Margoshes" <physnospamchem@cloud9.net> wrote:

>There isn't a simple, straightforward answer that I know of. I had an Oly
>3030, a camera that many people complained had a purple fringe problem. I
>looked carefully at images that were likely to show the effect, and couldn't
>find it. Perhaps there was some difference in the lens, the sensor, or the
>software in my camera.

Did you use the lowest ISO on most pictures, or shoot images with
extreme contrast? That is where sesnor-related purple fringing is most
likely to happen.

--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
Anonymous
December 28, 2004 9:42:13 PM

Archived from groups: rec.photo.digital (More info?)

In message <Xns95B8D5F2E23B6klotjohan@130.133.1.4>,
Roland Karlsson <roland_dot_karlsson@bonetmail.com> wrote:

>You have got some different answers regarding the cause,
>as always when this topic comes up :) 
>
>The easiest cure (if you cant avoid large contrast in
>the picture, particularly in the corners) is to desaturate
>purple. It is more efficient than one can imagine.
>
>Depending on your photo editor you can select purple
>using several methods. No matter how you do it, just
>desaturate the selection.

It would take more time, but it might be better to visually inspect the
mask and subtract true purple objects from it, or only select purple
areas manually.
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
Anonymous
December 29, 2004 3:00:30 AM

Archived from groups: rec.photo.digital (More info?)

In message <96iAd.13392$%k.1424985@weber.videotron.net>,
"m.b." <spamkiller@moon.net> wrote:

>When cyan fringes are on only one side of the subject, or red fringes on the
>opposite side, this is a true optical issue.

That's not purple fringing.
--

<>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
John P Sheehy <JPS@no.komm>
><<> <>>< <>>< ><<> <>>< ><<> ><<> <>><
!