MP and IQ

Simon97 · Feb 22, 2008

Phil and the other camera reviewers here often mention the issues with high megapixel count small sensor cameras. Limited dynamic range, noise and the effects of noise reduction and limited high ISO performance.

My issue is the noise and the effects of NR are creeping into the images at the lowest ISO on current cameras.

joe mama · Feb 22, 2008

GordonBGood said:
Your hypothesis of less DR per unit of sensor area is based on
smaller photosites saturating faster and I think that is your error.
For a given sensor technology there is no reason for smaller
photosites to saturate faster for a given exposure than larger ones
as saturation will occur at a particular electron density that will
be the same for each size of photosite. IE: Does a small rain gauge
fill faster than a large one?

Let's consider two different pixel sizes, A and B, such that A has twice the dimensions of B, and thus four times the area.

Let's say that pixel B becomes saturated after 50,000 photons. Then, given the same sensor efficiency, pixel A will become saturated at 200,000 photons. Now lets assume that four B pixels are arranged in a square, so that they look as if an A pixel were divided into four.

Let 200,000 photons fall onto pixel A. It will record all those photons. Now let 200,000 photons fall onto the "4-pack" of B pixels (B1, B2, B3, and B4). Now, if the photons are uniformly distributed, then 50,000 photons will fall into each of the B Pixels and all is the same. However, let's say the distribution of photos is not uniform and 80,000 photons fall onto B1, only 40,000 photons fall onto B2, another 60,000 photons fall onto B3, and only 20,000 pixels fall onto Pixel B4.

We see that the A Pixel records 200,000 pixels, but the 4-pack of B pixels only record 160,000 photons, since two of the pixels are oversaturated. Thus, the single A pixel records the DR more accurately than the 4-pack of B pixels.

Hence, a larger pixels will have more DR than smaller pixels, but that DR will come at the expense of detail. As long as individual pixels stay away from the saturation points, having smaller pixels incurs no penalty. But as soon as "enough" of the smaller pixels become overstaurated, there will be a noticable hit in DR.

--
--joe

http://www.josephjamesphotography.com
http://www.pbase.com/joemama/

GordonBGood · Feb 22, 2008

Yes, let's consider your sceneario and assume that packing efficiency vs. microlenses doesn't make too much of a difference as you have done, as follows:

joe mama said:
joe mama said:

Your hypothesis of less DR per unit of sensor area is based on
smaller photosites saturating faster and I think that is your error.
For a given sensor technology there is no reason for smaller
photosites to saturate faster for a given exposure than larger ones
as saturation will occur at a particular electron density that will
be the same for each size of photosite. IE: Does a small rain gauge
fill faster than a large one?

Click to expand...

Let's consider two different pixel sizes, A and B, such that A has
twice the dimensions of B, and thus four times the area.

Let's say that pixel B becomes saturated after 50,000 photons. Then,
given the same sensor efficiency, pixel A will become saturated at
200,000 photons. Now lets assume that four B pixels are arranged in
a square, so that they look as if an A pixel were divided into four.

Let 200,000 photons fall onto pixel A. It will record all those
photons. Now let 200,000 photons fall onto the "4-pack" of B pixels
(B1, B2, B3, and B4). Now, if the photons are uniformly distributed,
then 50,000 photons will fall into each of the B Pixels and all is
the same. However, let's say the distribution of photos is not
uniform and 80,000 photons fall onto B1, only 40,000 photons fall
onto B2, another 60,000 photons fall onto B3, and only 20,000 pixels
fall onto Pixel B4.

We see that the A Pixel records 200,000 pixels, but the 4-pack of B
pixels only record 160,000 photons, since two of the pixels are
oversaturated. Thus, the single A pixel records the DR more
accurately than the 4-pack of B pixels.

Ah, but for this situation you are running your sensors right at the clipping limit for the highlights in the image and this isn't where noise limits the effective DR. Yes, some of your higher resolution photosites are clipping where the large photosite was just at the clipping limit of photosite, but those remaining finer photosites gave you more highlight detail for the finer photosite pitch than the large one.

From a noise analysis, let's say that the large 'A' photosites have a black readout noise of 10 electrons or a best case DR limit for full signal as compared to minimum noise of 200000:10 or about 20000:1 and the smaller 'B' photosites have a black readout noise of 5 electrons or a best case DR limit of 10,000:1, as might typically be the case with today's large sensors (larger sensors have more readout noise in electrons but better best case DR limits due to more electrons). At saturation, the statistical noise due to photon/electron variation is proportional to the square root of the number of electrons or about 447:1 and 224:1 for the larger/smaller photosites respectively, which as you can see swamps the readout noise, but that's not how we determine DR, else the best current 35 mm. DSLR's would only have a DR of about 8 stops. If we were to judge the DR from the highlight noise, we would need truly humungous sensors in order to be able to get anything approaching a 10 to 12 stop DR with much image quality. In actual fact, our eyes don't sense the noise level (or detail level) in highlights as much as we do in shadows due to the human visual systems logarithmic tone response.

We determine DR by when we stop being able to detect steps in tonality at the dark end no matter how much we boost exposure, and that is limited by readout noise. This is quite clear in the raw Imatest charts as provided by Jay Turberville. Thus DR is determined by the noise floor which is the readout noise and would be over 14 stops and over 13 stops for the large and small 'A' and 'B' sized photosites in your example, respectively, at a fairly poor image quality acceptance level.

joe mama said:
Hence, a larger pixels will have more DR than smaller pixels, but
that DR will come at the expense of detail. As long as individual
pixels stay away from the saturation points, having smaller pixels
incurs no penalty. But as soon as "enough" of the smaller pixels
become overstaurated, there will be a noticable hit in DR.

Joe, we agree in principle here, except that DR is not determined at the highlight clipping end of the luminance scale but rather at the dark end of the scale. Since we agree that the noise floor for the large photosites is pretty much the same as the noise for the small photosites downsampled to the large photosite resolution which noise floor represents a particular luminance level, also agreeing that the clipping limit for the large photosites represents the same luminance limit for the smaller photosites, the only DR we have lost is above that upper clipping limit. DR is still the upper clipping limit over the noise floor limit and that is the same for the large photosites as for downsampled smaller photosites.

The DR "lost" in clipping the smaller photosites which are capable of picking up the finer detail in tone variation was never really there in the first place for the larger photosites.

Regards, GordonBGood

joe mama · Feb 22, 2008

GordonBGood said:
Ah, but for this situation you are running your sensors right at the
clipping limit for the highlights in the image and this isn't where
noise limits the effective DR. Yes, some of your higher resolution
photosites are clipping where the large photosite was just at the
clipping limit of photosite, but those remaining finer photosites
gave you more highlight detail for the finer photosite pitch than the
large one.

That's a good point. : )

GordonBGood said:
From a noise analysis, let's say that the large 'A' photosites have a
black readout noise of 10 electrons or a best case DR limit for full
signal as compared to minimum noise of 200000:10 or about 20000:1
and the smaller 'B' photosites have a black readout noise of 5
electrons or a best case DR limit of 10,000:1, as might typically be
the case with today's large sensors (larger sensors have more readout
noise in electrons but better best case DR limits due to more
electrons).

Hmm. For the same efficiency of sensor, would not the A pixel have a read noise of 20 electrons if the read noise were 5 electrons for the B pixel? If so, then is the scenario you present above more a "real world" scenario than a case of "equal efficiency"?

GordonBGood said:
At saturation, the statistical noise due to photon/electron variation is
proportional to the square root of the number of electrons or about 447:1
and 224:1 for the larger/smaller photosites respectively, which as you can
see swamps the readout noise, but that's not how we determine DR, else
the best current 35 mm. DSLR's would only have a DR of about 8 stops.
If we were to judge the DR from the highlight noise, we would need truly
humungous sensors in order to be able to get anything approaching a 10 to
12 stop DR with much image quality. In actual fact, our eyes don't
sense the noise level (or detail level) in highlights as much as we
do in shadows due to the human visual systems logarithmic tone
response.

Interesting!

GordonBGood said:
We determine DR by when we stop being able to detect steps in
tonality at the dark end no matter how much we boost exposure, and
that is limited by readout noise. This is quite clear in the raw Imatest
charts as provided by Jay Turberville. Thus DR is determined by the noise
floor which is the readout noise and would be over 14 stops and over 13
stops for the large and small 'A' and 'B' sized photosites in your example,
respectively, at a fairly poor image quality acceptance level.

Just to be clear on that point: we are defining DR as DR = ln (F/R) / ln 2 where F is the maximum fill capacity of the pixel in electrons and R is the read noise in electrons, right? So, if having the same efficiency meant the same read noise, and fill capacity is proportional to pixel area, then the DR would be the same regardless of pixel count. What am I missing? Is it how I define "efficiency"?

GordonBGood said:
GordonBGood said:

Hence, a larger pixel will have more DR than smaller pixels, but
that DR will come at the expense of detail. As long as individual
pixels stay away from the saturation points, having smaller pixels
incurs no penalty. But as soon as "enough" of the smaller pixels
become overstaurated, there will be a noticable hit in DR.

Click to expand...

GordonBGood said:
Joe, we agree in principle here, except that DR is not determined at
the highlight clipping end of the luminance scale but rather at the
dark end of the scale.

From the DR formula I gave (if correct), it would seem that DR is determined at both the dark and the clipping end of the scale.

GordonBGood said:
Since we agree that the noise floor for the large photosites is pretty much
the same as the noise for the small photosites downsampled to the large
photosite resolution which noise floor represents a particular luminance level,

Could you expand on that a bit more, please?

GordonBGood said:
also agreeing that the clipping limit for the large photosites represents the
same luminance limit for the smaller photosites, the only DR we have lost is
above that upper clipping limit.

Yes.

GordonBGood said:
DR is still the upper clipping limit over the noise floor limit and that is the
same for the large photosites as for downsampled smaller photosites.

Yeah, that's the part I'm missing. How exactly do you compute the DR (and noise) for the downsampled image?

GordonBGood said:
The DR "lost" in clipping the smaller photosites which are capable of
picking up the finer detail in tone variation was never really there
in the first place for the larger photosites.

Yes. I get that. Thanks for the great explanation! I look forward to your explanation in the details I'm missing.

--
--joe

http://www.josephjamesphotography.com
http://www.pbase.com/joemama/

Jay Turberville · Feb 22, 2008

misha marinsky3 said:
The thing about pixel peeping is this: in the days of film, we did
not do the equivalent. We just looked at prints, held a viewing
distance - and everyone was satisfied with the results.

Or used an 8x or 10x loupe to look at negatives and transparencies. I've scanned some older Kodachromes, and when looking at the scans at 100% pixels, I've noticed things like chromatic aberrations that I never noticed with a loupe or with prints.

misha marinsky3 said:
I exclusively shot Tri-X, developed in Diafine, and enlarged on Kodak
Polycontrast.

I shot a lot of films, including TechPan developed for continuous tone.

--
Jay Turberville
http://www.jayandwanda.com

GordonBGood · Feb 23, 2008

Comments as interspersed:

joe mama said:
joe mama said:

From a noise analysis, let's say that the large 'A' photosites have a
black readout noise of 10 electrons or a best case DR limit for full
signal as compared to minimum noise of 200000:10 or about 20000:1
and the smaller 'B' photosites have a black readout noise of 5
electrons or a best case DR limit of 10,000:1, as might typically be
the case with today's large sensors (larger sensors have more readout
noise in electrons but better best case DR limits due to more
electrons).

Click to expand...

Hmm. For the same efficiency of sensor, would not the A pixel have a
read noise of 20 electrons if the read noise were 5 electrons for the
B pixel? If so, then is the scenario you present above more a "real
world" scenario than a case of "equal efficiency"?

No, the electron noise seems not to increase as the area of the sensor but rather as the root of the area; I don't have any exact theories as to why. This mean that the readout noise in converture level units (ADU's) appears to decrease as the square of the increased area multiplier as the total number of electrons increases directly with area.

joe mama said:
joe mama said:

We determine DR by when we stop being able to detect steps in
tonality at the dark end no matter how much we boost exposure, and
that is limited by readout noise. This is quite clear in the raw Imatest
charts as provided by Jay Turberville. Thus DR is determined by the noise
floor which is the readout noise and would be over 14 stops and over 13
stops for the large and small 'A' and 'B' sized photosites in your example,
respectively, at a fairly poor image quality acceptance level.

Click to expand...

Just to be clear on that point: we are defining DR as DR = ln (F/R)
/ ln 2 where F is the maximum fill capacity of the pixel in electrons
and R is the read noise in electrons, right? So, if having the
same efficiency meant the same read noise, and fill capacity is
proportional to pixel area, then the DR would be the same regardless
of pixel count. What am I missing? Is it how I define "efficiency"?

Yes, your efficiency definition doesn't include the following: It appears (there is likely a theory, but I only know this from pragmatic measurement) that readout noise as a percentage of full scale drops as the square root of the area increase. Thus bigger photosites have a true DR advantage (ie a extra factor of two or one stop in your example, and it is precisely this same one stop improvement one gets by down-res'ing down-sampling the finer photosite pitch to the larger one.

joe mama said:
joe mama said:

joe mama said:

Hence, a larger pixel will have more DR than smaller pixels, but
that DR will come at the expense of detail. As long as individual
pixels stay away from the saturation points, having smaller pixels
incurs no penalty. But as soon as "enough" of the smaller pixels
become overstaurated, there will be a noticable hit in DR.

Click to expand...

Click to expand...

joe mama said:

Joe, we agree in principle here, except that DR is not determined at
the highlight clipping end of the luminance scale but rather at the
dark end of the scale.

Click to expand...

From the DR formula I gave (if correct), it would seem that DR is
determined at both the dark and the clipping end of the scale.

Your formula is correct, but as the clipping limit when converted to EV levels is a constant for a given ISO sensitivity and given sensor technology, it is the 'R' level that changes with changing photosite pitch.

joe mama said:
joe mama said:

Since we agree that the noise floor for the large photosites is pretty much
the same as the noise for the small photosites downsampled to the large
photosite resolution which noise floor represents a particular luminance level,

Click to expand...

Could you expand on that a bit more, please?

Downsampling reduces the noise as the square root of the ratio of downsampling so that a 4:1 downsampling as in your sample reduces the floor readout noise by a factor of two. This is also about the ratio of the readout noise is real larger photosites as compared to the smaller real photosites (for unkown reasons, but by measurement).

joe mama said:
joe mama said:

also agreeing that the clipping limit for the large photosites represents the
same luminance limit for the smaller photosites, the only DR we have lost is
above that upper clipping limit.

Click to expand...

Yes.

joe mama said:

DR is still the upper clipping limit over the noise floor limit and that is the
same for the large photosites as for downsampled smaller photosites.

Click to expand...

Yeah, that's the part I'm missing. How exactly do you compute the DR
(and noise) for the downsampled image?

As above, the readout noise, if random with a standard distribution, will be reduced by the square root of the increase in area of the new combined photosites as compared to the orginal photosites; therefore, the DR will increase as the square root of the increased photosite area coverage. As in your sample the DR of the larger photosites or of the smaller photosites down-sampled to the larger photosite pitch will be increased by a factor of two.

joe mama said:
joe mama said:

The DR "lost" in clipping the smaller photosites which are capable of
picking up the finer detail in tone variation was never really there
in the first place for the larger photosites.

Click to expand...

Yes. I get that. Thanks for the great explanation! I look forward
to your explanation in the details I'm missing.

You're welcome, GordonBGood

Maddiestoys · Feb 23, 2008

I know the G9 is still a compact camera - I realize it is not a DSLR, and would not produce images as crisp as a DSLR. But am I likely to see a noticeable improvement over the 850 at a sporting event - or would I need to step up further to a DSLR to get a decent shot even for 4 x 6 prints?

Thanks

Maddie

Jay Turberville · Feb 23, 2008

Maddiestoys said:
I know the G9 is still a compact camera - I realize it is not a DSLR,
and would not produce images as crisp as a DSLR. But am I likely to
see a noticeable improvement over the 850 at a sporting event - or
would I need to step up further to a DSLR to get a decent shot even
for 4 x 6 prints?

"Crispness" may or may not be worse. The reason to consider the DSLR for sporting events is largely one of camera response and low light capabilities.

A DSLR with a decent fast lens will almost surely give better image quality in low light. It will write files to the memory card faster and will have faster autofocus and improved shutter response in most cases. Overall, it is generally a better choice for shooting sports, especially indoor sports.

--
Jay Turberville
http://www.jayandwanda.com

Maddiestoys · Feb 23, 2008

Sorry I was not clear- I am mostly having difficulty in day light- I'm shooting football and baseball outdoors, but stll have quite a bit of difficulty getting images without blur.

Is this more likely due to human error?

Would I get a better shot with the G9- or is the only chance for a reasonable shot to step all the way up to a DSLR?

Thank you so much (baseball season is just around the corner)

Maddie

Jay Turberville · Feb 23, 2008

Maddiestoys said:
Sorry I was not clear- I am mostly having difficulty in day light-
I'm shooting football and baseball outdoors, but stll have quite a
bit of difficulty getting images without blur.

Is this more likely due to human error?

Without some example images, I have no way of knowing. It could be poor focus, the use of the wrong camera settings, or poor technique. For daylight images, I wouldn't expect that you'd have a lot of blur.

Post an example and maybe we can figure it out.

--
Jay Turberville
http://www.jayandwanda.com

joe mama · Feb 23, 2008

GordonBGood said:
GordonBGood said:

Yes. I get that. Thanks for the great explanation! I look forward
to your explanation in the details I'm missing.

Click to expand...

GordonBGood said:
You're welcome, GordonBGood

You're two for two! I much appreciate the response -- extremely enlightening.

--
--joe

http://www.josephjamesphotography.com
http://www.pbase.com/joemama/

Maddiestoys · Feb 23, 2008

Unfortunately- through the magic of digital photography- the worst shots have been deleated.

I do have some pretty bad shots I could show you - but I don't know how to post pictures.

I usually keep the camera on auto for outdoor shots. I do not know what settings would be best for outdoor action shots. For indoor/poor lighting I have the best luck with manual, with the flash turned off.

Outdoor still images are usually pleasing to me, but the football shots are rarely clear. Baseball is not as problematic - a shot of a batter is not very difficult to get because the subject is not running. Even baserunners are still until the pitch, and I know exactly where the subject is headed. Football is much more of a challenge for me.

There is no "sports" selection in the predesigned scene modes, but maybe I could improve my chances at better images if I knew the proper settings.

Jay Turberville · Feb 23, 2008

... I'm not willing to give a general photography class via forum discussions. So in short, I can't answer your question.

I will say this, you need to figure out why your shots are blurred to come to a good conlusion about how to fix it.

But if you aren't going to do that, I'd suggest a DSLR that has in-camera stabilization. Set the ISO to 200 or 400 and shoot away in program auto mode with IS turned on. You'll probably do OK.

--
Jay Turberville
http://www.jayandwanda.com

Maddiestoys · Feb 23, 2008

Thanks so much for all of your help

...perhaps a photography class is in order to help me with my issues- and I will be able to figure out if the problem is the settings, or my error, or I just need to move up to a DSLR

Thanks again-

Maddie

Jay Turberville · Feb 23, 2008

Maddiestoys said:
or I just need to move up to a DSLR

I don't necessarily consider DSLRs a "move up." I think compacts and DSLRs both have their places. Sports is generally a better place for DSLRs.

Maddiestoys said:
Thanks again-

Best of luck.

--
Jay Turberville
http://www.jayandwanda.com

richard stone · Feb 24, 2008

Maddiestoys said:
Thanks so much for all of your help

...perhaps a photography class is in order to help me with my issues-
and I will be able to figure out if the problem is the settings, or
my error, or I just need to move up to a DSLR

Thanks again-

Maddie

You know, there are lots of photography books that address almost every photographic issue, and digital "issues" are not that different from film, so even older books on technique are still quite relevant.

Secondly, we each have to find our own style and interests, so getting "help" from utter and complete strangers on the net is not much good, unless you really like what you see and want to do the same thing for the purpose of practice.

Actually, I think some of the older 5mp digicams still work really well, and it's almost easier, as you seem to have noticed, to do without some of the "features" on some of the newer cameras, although the red-eye issue is a big one.

DSLR's can produce much better images than digicams. It's not even close. But they are also a lot bigger and much less likely to be there when you want one. For sports the modern DSLR's can be excellent. Instant AF and instant exposure when you push the shutter button.

Finally, what really determines the quality of your images is what you put into them, what you see and want to express, and your purpose in taking the image. Not the camera. Not the sharpness of the image. You could have a lot more talent taking pictures and your images could be a lot better than the people you are discussing this with, a lot of whom tend to be "gearheads" and more interested in the cameras as tools and photography as technique than beautiful images or images that have a purpose.

Want to visit a site with some great images? Try rangefinderforum.com It's a whole different look.

Richard

--
My small gallery: http://www.pbase.com/richard44/inbox

Jay Turberville · Feb 24, 2008

richard stone said:
DSLR's can produce much better images than digicams. It's not even
close.

Actually, the better compacts in good daylight come very close. And if the DSLR doesn't use an excellent lens, sometimes do clearly better.

richard stone said:
For sports the modern DSLR's can be
excellent. Instant AF and instant exposure when you push the shutter
button.

Well, not instant, but yes generally faster. The pro cameras are sometimes a lot faster.

--
Jay Turberville
http://www.jayandwanda.com

Maddiestoys · Feb 24, 2008

richard stone said:
Maddiestoys said:

Thanks so much for all of your help

...perhaps a photography class is in order to help me with my issues-
and I will be able to figure out if the problem is the settings, or
my error, or I just need to move up to a DSLR

Thanks again-

Maddie

Click to expand...

You know, there are lots of photography books that address almost
every photographic issue, and digital "issues" are not that different
from film, so even older books on technique are still quite relevant.

I agree- I have been trying to do some reading in order to find out how to properly set the camera manually, when "auto" seems to be failing me. Hopfully the reasearch will help.

richard stone said:
Secondly, we each have to find our own style and interests, so
getting "help" from utter and complete strangers on the net is not
much good, unless you really like what you see and want to do the
same thing for the purpose of practice.

Still- I appreciate the time people give to share their experiences with me- then its up to me to sort out what might be useful.

richard stone said:
Actually, I think some of the older 5mp digicams still work really
well, and it's almost easier, as you seem to have noticed, to do
without some of the "features" on some of the newer cameras, although
the red-eye issue is a big one.

So true- my son is using my ols 4mp s400-and still gets great shots - except for the red eye. I wouldn't give up my in camera red eye correction for ANYTHING!. Post processing is a real problem for me.

richard stone said:
DSLR's can produce much better images than digicams. It's not even
close. But they are also a lot bigger and much less likely to be
there when you want one. For sports the modern DSLR's can be
excellent. Instant AF and instant exposure when you push the shutter
button.

I REALLY don't want a DSLR. I was willing to look into the G9 - if it would make a significant difference in "real world" 4 x 6 prints.

richard stone said:
Finally, what really determines the quality of your images is what
you put into them, what you see and want to express, and your purpose
in taking the image. Not the camera. Not the sharpness of the
image. You could have a lot more talent taking pictures and your
images could be a lot better than the people you are discussing this
with, a lot of whom tend to be "gearheads" and more interested in the
cameras as tools and photography as technique than beautiful images
or images that have a purpose.

I'm quite clear about my puropse in taking images. Quite simply- I am preserving family memories. I enjoy framing- sharing - and scrapbooking my photos. I hold no grand ideas about producing the "be all end all" image. I'm the mom that family and friends look to- when trying to find out who has their camera with them.

The only reason blur has become an issue for me- is because my outdoor action shots are not clear at all, and I was wondering if I should consider a G9. However it seems that working with the settings on my current camera would be a smarter first step.

Regardless- I doubt that I will be investing in a DSLR- if its the only way-its more likely that I will just continue to settle for the posed team photo after the game.

richard stone said:
Want to visit a site with some great images? Try
rangefinderforum.com It's a whole different look.

I'll check it out.

Thanks for all of your help - an a refreshing perspective!

richard stone said:
Richard

Maddie

richard stone said:
--
My small gallery: http://www.pbase.com/richard44/inbox

Koosla · Feb 24, 2008

joe mama said:
joe mama said:

And frankly, I'm not even sure about that. On a "per pixel" basis
where DR is based on a noise limit, yes. But on a per image area
basis that normalizes for final image viewing, I'm not at all sure
that it is correct. Since you are packing more pixels into a give
area of response, you get more signal. And with each somewhat
noisier pixel taking up a smaller area, the aparent noise is lower.
So when final images are compared side-by-side, I'm not at all
convinced that there would be a practical difference.

Click to expand...

That's a good point, but I'm pretty sure I was right (but not 100%
sure). The reason is that if the individual pixel looses information
(oversaturated), there's no way to reconstruct that information from
surrounding pixels.

I'm even less sure (I'd guess about 30% sure... LOL), but unless we're talking severely bad overexposure, there still might be some advantage with increased resolution.

With near-total overexposure, some pixels still retain some information... it might be fuzzy, it might be only in one or two of the channels, but it'd still be there. My point is, with increased resolution (and considering a somewhat larger sensor that might, in effect, make the photodiodes pretty much identical in size), you'd get more pixels representing the same overexposed area, therefore a bit less fuzziness... therefore a bit more DR, at least in practical terms (i.e. recoverable details).

I'm guessing, though, and probably way out of my league

joe mama · Feb 24, 2008

Koosla said:
With near-total overexposure, some pixels still retain some
information... it might be fuzzy, it might be only in one or two of
the channels, but it'd still be there. My point is, with increased
resolution (and considering a somewhat larger sensor that might, in
effect, make the photodiodes pretty much identical in size), you'd
get more pixels representing the same overexposed area, therefore a
bit less fuzziness... therefore a bit more DR, at least in practical
terms (i.e. recoverable details).

Gordon's explanations (a bit further up) are spot-on.

Koosla said:
I'm guessing, though, and probably way out of my league

Did you think my situation was any different? : )

--
--joe

http://www.josephjamesphotography.com
http://www.pbase.com/joemama/

MP and IQ

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