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PostPosted: Fri Oct 10, 2008 10:21 pm 
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Oh boy(s), I'm tired with all the same bickering again and again about an issue that is so super easy to understand. Let's see what Otto asked:
"How is this (i.e. pixel-density=PD) supposed to give one an idea of the quality of these pixels and corresponding images created?"
As some here pointed out correctly:
(1) Higher PD gives you higher resolution
(2) Lower PD gives you higher dynamic range and higher sensitivity*

So it's always a compromise between resolution and DR/sensitivity/noise. As such PD is not a key performance indicator in itself. Only bringing the sensor size into the equation do you get those two most important factors that determine the IQ of a sensor (read again*):
- number of pixels
- size of pixels
Now there is a plethora of different combinations of sensor size with PD that all result in different sensors having their specific benefits and short comings. Discussing this is like discussing the different possibilities to combine different sizes of car bodies with more or less powerful engines: You get what you assemble. Simple as that!

And don't let some company fool you into thinking that the next sensor generation will change anything in this game. As soon (or as long) as the latest sensor/chip/micro-lens technology is applied to all sensors all combinations of sensor-size and PD will have the same relative performance against oneanother with respect to resolution and DR/noise as before. But in absolute terms the new sensor technologies improve the performance.

So the following statements will always hold true:
- if you need the highest resolution go for a sensor with the highest PD
- if you need the highest DR / lowest noise go for a sensor with the lowest PD
- if you need high resolution with high DR / low noise go for the largest sensor you can afford.

There are so many choices, you just need to know what you want...

------
* assuming sensor technology is of the same comparable level.

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 Post subject: "standards?"
PostPosted: Fri Oct 10, 2008 10:41 pm 
Quite so pg,
as the LENS so often makes or breaks a camera deal.
"Professional Lens Quality aside",
I am wondering if "Industry" might actually
self-regulate to a point of saying, this camera belongs to
A/B/C/D
class for example, related to just how large a print beyond which
the image is no longer recommended.
Perhaps, sizes like 5x7, 10 x8,
A4, A3 and so on.
So often we are not talking about professional lenses and print size/quality but more in the area of say a fixed lens consumer
travel/tourist camera. That is, EVERYTHING other than a Pro Cam.
So would it be too much to ask if instead of
highly debatable Pixel Density numbers, we can have
actually recognizable and acceptable Print Boundaries/Categories.
Eg:
A travel camera (say a compact) might be really fine up to
22"x14" and no more in which case,
the consumer ought to know this.
It's like a car licenced to carry x number of passengers.
Simple and effective because we all know what
category the car falls under.
Presently, Industry has a vested interest in keeping the consumer
very confused and I believe they're using the Supermarket
technique of overwhelming the shopper with
more products than he could poke a stick at, which has the effect of
keeping him in the supermarket longer and therefore more likely that he will find/buy something he "desires" whether he needs it or not.
Pros generally know what they are doing, but I am talking about the
mums and dads who splash their cash thinking
this camera is better because they've been led to think
35mp/sq. cm is WAY better than 5mp/sq.cm!!!!
That's probably 90+% of customers!
However, I don't think the manufacturers will even take notice of this approach because it's not in their interest. It's up to Editors/Reviewers and Consumers to come up with some sense would you agree?
BTW I like your summing up Thomas.
Otto


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 Post subject:
PostPosted: Sat Oct 11, 2008 8:44 am 
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Fortunately we're talking about hard physical facts that are not debatable:
- Sensor size: measurable!
- Pixel density: measurable!
- S/N ratio / dynamic range: measurable!
- amp noise: measurable!
- photon well capacity: measurable!
- sharpness of lens: measurable!
The only thing that adds a layer of complexity here is the many combinations of those factors. But again: nothing to debate, just cold, hard, physical facts.
What the marketing department of any camera manufacturer makes out of these facts is sometimes debatable and certainly not always educating customers :(

And I wish the debate would always concentrate on the facts (and some example images :wink: ) :idea:

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Last edited by Thomas on Tue Oct 14, 2008 10:12 pm, edited 1 time in total.

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 Post subject: facts
PostPosted: Sat Oct 11, 2008 11:24 am 
First, facts are just academics in a vacuum unless represented in an actual camera. Second, I spent a lot on my cameras, including the LX3. Third, I posted a number of really complex images on the LL forum, easy to get to. There's no debate in those images, but, a little teeth-gnashing perhaps. And I like my LX3, but we should look at those images a little closer, since I think the combination of factors makes the overall picture much more complex than what a lot of the debate suggests.


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 Post subject:
PostPosted: Sat Oct 11, 2008 11:34 am 
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Dale, don't make us search for the correct/best photo in your collection to prove your points. Just a little link to one exemplary image plus an accompanying statement would do us all a favor!
Just remember we would all be less than satisfied here if the proof is not a 100% crop or full-size image :wink:

Btw. If "facts" = "vacuum" I don't see any sense to continue a debate that should be based on facts not fiction :?

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Last edited by Thomas on Tue Oct 14, 2008 10:14 pm, edited 1 time in total.

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 Post subject:
PostPosted: Sat Oct 11, 2008 11:42 am 
It definitely helps making such short and clear statements. If Dale could do the same with regards to his criticisms concerning the LX3 that might help focus the debate.

Ben
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 Post subject:
PostPosted: Sat Oct 11, 2008 11:45 am 
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I think the main problem in this debate is complexity. In this aspect Dale is perfectly right: The interplay between sensor, lens, AA-filter, amplifiers, D/A converters, and software is hugely complex. But that doesn't help people understand the individual parts of the total equation that determines IQ.

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Last edited by Thomas on Sat Oct 11, 2008 12:10 pm, edited 1 time in total.

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 Post subject: Sample LX3 images
PostPosted: Sat Oct 11, 2008 11:54 am 
Here's some samples. I don't know how long these links will last.

Best-case LX3 photos:
http://luminous-landscape.com/forum/ind ... opic=28514

Low light comparison LX3 to TZ5:
http://luminous-landscape.com/forum/ind ... opic=28200

Daylight comparison of LX3 to TZ5:
http://luminous-landscape.com/forum/ind ... opic=27713


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 Post subject:
PostPosted: Sat Oct 11, 2008 12:40 pm 
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Thanks for the links Dale!
In your 2nd link the left photo seems a little clearer/sharper to me but that might be a result of the lens or focussing or processing or sensor or any combination of those factors.
So it's hard to say who's the culprit.

Btw. If you could leave more of the original EXIF-info in the images that would help. You software or the upload-process seems to strip some of the data away.

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 Post subject: Photos
PostPosted: Sat Oct 11, 2008 1:02 pm 
Thomas wrote:
Thanks for the links Dale!.....
.....In your 2nd link the left photo seems a little clearer/sharper.....
.....If you could leave more of the original EXIF-info in the images that would help.....

Links are difficult since I use a mobile, and have to go aways to get to a desktop. In the 2nd link, the LX3 pic is definitely better, but it's still marginal, and mostly the 10/9 mp factor. I think the 4-image link is the definitive comparison. In any case, I'm still looking for ways to get more use from the LX3, but the opportunities are very limited due to the limited focal range. On the EXIF's etc., if I were doing this more professionally I would change some things, but since the LL guys are so accomodating not complaining about image size, and since I do forum work from a mobile, I don't know when that will happen.


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 Post subject:
PostPosted: Sat Oct 11, 2008 1:14 pm 
Thanks Dalethorn.

I'll take your word for it that there is truly no extra detail revealed beyond the 2400x1800. If so, then to me, the LX3 has records a marginally higher (almost negligible) level of detail then the TZ5.

The most obvious area where the LX3 seems to pull ahead is in the shadows as you yourself said that the extra noise of the TZ5 was noticeable. The LX3 also seems to keep the highlights better in the shot of the gardens. Wasn't that all the bigger sensor was about? It shows better noise control and a larger dynamic range as promised. Perhaps not as much as you or others would have liked but it's there and it's quite obvious.

So it performs better in low light/shadows and has larger dynamic range. It also has a constant f/2.8 and a 24mm lens. You've already stated that you don't agree with the whole idea of wider lenses but so many people have asked for this to be introduced to a compact. They can't all be wrong especially when it comes to stating their wants.

You seem very happy with your TZ5 so good for you but you can't expect all of us to believe the LX3 and it's entire design/engineering direction is wrong just because it doesn't suit your preferences.


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 Post subject: photos
PostPosted: Sat Oct 11, 2008 1:14 pm 
My main point in posting the images was very relevant to pixel density, in that Panasonic made very strong claims about the much less dense LX3 sensor, and those claims were trumpeted long and loud by many forums. Yet, when viewing the results at the pixel level or image level, the difference seemed negligible to me. Now that may be purely a failure of Panasonic, or perhaps (unlikely) that I'm not shooting the type of scenes they had in mind for their design. If anyone else can shoot some scenes with the LX3 and a 1/2.33 sensor camera side-by-side, and post them full size, we might not be able to determine the true difference anyway, unless the overall brightness, contrast, and sharpness are matched very well. What I would really like to see are image comparisons like I did, using the Canon G10 and LX3.


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 Post subject:
PostPosted: Sat Oct 11, 2008 1:22 pm 
The way I see it, none of Panasonic's compacts have been better than their competition in the area of noise performance for the same sensor size and resolution. There are many other factors to take into consideration that most consumers probably don't know of and only Matsushita's engineers would know but just looking at the them on the screen, there is no Panasonic I would buy for it's sensor alone. Panasonic makes some very good camera's like TZ series (I know people who have this, I like it too) but sensor design just does not seem to be one of their strong points. If the LX3 has failed to impress, I would put it down to this reason.


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 Post subject:
PostPosted: Sat Oct 11, 2008 1:42 pm 
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As to the man factors that influence IQ and whihc is closely related to the main topic of this thread (remember? "Pixel Density"!) are the algorithms that do noise reduction (be them either in camera are in some post-processing software.
Speaking in general here noise reduction algorithms tend to reduce detail. Or to put it in more technical terms: those algorithms try to smooth sample variations in brightness between adjacent pixels (ok that still is a very simple desciption of what is going on, but you capture the gist of it).

Now comes the interesting part but I first have to set up my assumptions:
- consider two identically sized sensors (let's say FF/FX)
- build from the same technology incl. micro lenses etc.
- sensor L is a low-density 9 MPix and sensor H is a high-density 36 MPix sensor
- assume AA-filters are perfectly matched to each sensors resolving power
- assume shooting with a lens that easily outresolves the 36 MPix sensor and is perfectly focussed (don't look sceptical, you can buy one of those!)
- assume just one moment (I'll come to this later) that four photo-sites of sensor H together have the same photon full-well capacity as one photo-site of sensor L.

The big Q is: What will happen, if you pixel-bin every four photo-sites of sensor H together by some clever noise reduction technique?
The resulting shot with sensor H should be of the same resolution, the same noise, the same dynamic range as the the shot with sensor L (not processed with any noise-reduction technique) :shock: :idea:
If this is true the higher PD sensor H is much more flexible than sensor L as you can adjust resolution and noise through (post-)processing of the image to either match output from sensor L or just use the full high-res capabilites of H under ideal/bright conditions.

Well, does this sound familiar? Yes, it's exactly what many p&s cameras do and even the large DSLRs to it: they crank up noise-reduction (and thus lose detail and resolution) at higher ISO. So my train of thought must have some ruth to it.

Unfortunately though my assumption "that four photo-sites of sensor H together have the same photon full-well capacity as one photo-site of sensor L" is not exactly true in real-world chip etching: with the mind-bogglingly small structures on a chip there is a lot of space wasted betwenn the photo-sites. Sensor L would have pixel-spacing of roughly 10 micron, sensor H of 5 micron. Now if you lose a fix 2 micron per photo-site to borders, wiring etc. that would yield a net area of 64 square-micron per photo-site of sensor L and only 9 square-micron for H. Now pixel-binning four cells from H together gives you an effective 36 square-micron photo-site which unfortunately still is only 56% of the area of one photo-site of L. So in this case you lose an effective 1EV against the same-sized sensor with the lower PD :?

Well all is not lost because new manufacturing processes reduce the size of "dead" structures on a chip, try to put the wiring on the backside etc.. So we can assume to get closer to see much smaller losses from pixel binning / noise reduction versus the low pixel density sensors.

So will there be no Nikon D3 (=12MP) vs D3x (think 24-30MP) in the future? Well even in an ideal "borderless" sensor manufacturing process where the loss from binning is negligible one problem remains: You need to process much more pixels from a D3x sensor than from a D3 sensor and that in turn still costs more processor-time and transfer time to memory. As long as those speed-bumps exist there will always be lower density sport-shooter cameras with high fps and higher density landscape-shooter cameras with lower fps!

But if those speed barriers are removed, how knows...

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 Post subject:
PostPosted: Sat Oct 11, 2008 1:47 pm 
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Addendum:
Quote:
...Panasonic made very strong claims...
That's the main fault: marketing departments blowing differences out of proportion and people having difficulty in seeing those differences as clearly as the marketing made them believe :?
Same shame on the lab tests that made me believe that the Tamron 70-200/2.8 is a sharp lens only by manually optimizing the focus on all their test-chart shots :cry:

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