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Author Topic: Is This The End Game?  (Read 14816 times)
Jonathan Wienke
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« Reply #20 on: July 18, 2005, 12:48:54 AM »
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It's a well known fact that, with a good prime lens, a sturdy tripod, flawless technique and the right type of film developed in the appropriate developer to bring out the greatest detail, it's possible to record detail up to 100 lp/mm on 35mm film.

How does this compare with the 45-55 lp/mm limit of the 1Ds?
The catch is that this is only achievable for high contrast subjects like B&W resolution test charts and the like. Real-world subjects require much more film area for the grain patterns to average out to a given color, in much the same way that inkjet printers can achieve extremely high resolution (say 1440 DPI for most Epsons) for text and other high-contrast subject matter, but due to the dithering required to generate arbitrary colors in the midtones, they can't do much better than a 300DPI continuous-tone LightJet for most real-world images. That is ultimately the flaw in Clark's math; the dithering introduced by film's grain structure significantly reduces the effective usable lp/mm for any subject matter that is not high-contrast black & white, typically by a factor of 3 to 5. In contrast, this limitation does not apply to digital capture, except for Bayer-type cameras and highly saturated colors (color interpolation algorithms do not work well when you have adjacent pixels clipped to minimum and maximum values).

If you're shooting high-contrast B&W test charts, Clark's assertions are fairly accurate. But when shooting anything else, their validity is completely compromised.
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Ray
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« Reply #21 on: July 19, 2005, 01:03:51 AM »
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And where were all you res buffs when Kodak discontinued Ektar 25? IMHO that's the only color fim that approached the creamy skies of digital, and it also resolved close to 200 lp/mm, reputedly the highest-resolution color film ever mass-produced. Yet, today, I still prefer a 1Ds print to an Ektar 25 print. I suspect that's because the old lenses were simply not as sharp as the current lenses.
Hey! I wonder if this is a conspiracy. (Okay! Only joking. I'm not into conspiracy much - but it does exist, of course.)

Before I went digital, I was very impressed with Royal Gold 25 color negative as well as Technical Pan B&W. I've still got a few of both film types in the fridge, now well past their use by date.

Kodak have discontinued both of these films. It seems to me just a little bit odd that in the march towards full digitalisation, Kodak was quick to discontinue the films that could best compete with their DSLR cameras.

Of course, there's no arguing with a statement along the lines, "These films were not popular and therefore not economic to produce".
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Jonathan Wienke
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« Reply #22 on: July 19, 2005, 08:54:52 PM »
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I thought it had been well established that 9 million Foveon photosites are equal to 6 million Bayer type photosites, ie. the 3 megapixel SD9/10 produces an image quality roughly equal to a D60 or 10D, including resolution.
As RAW converters' Bayer interpolations routines improve, the quality difference is shrinking, and other tools and techniques are closing other aspects of the gap. For example, Focus Magic does a truly excellent job of undoing the slight blurring caused by the AA filter without reintroducing moire or other artifacts. The gap is shrinking, but it will never quite disappear.
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ijrwest
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« Reply #23 on: July 21, 2005, 03:12:53 PM »
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You are on the right track by looking at comparisons with a 'true' image produced by downsampling. That's what I was talking about earlier.

But I don't think using jpeg file sizes is a valid way of comparing the images. You are measuring the amount of information, but you are not measuring whether it is 'true' information.

If you sharpen an image then jpeg doesn't compress it so much and (as you say) you have more information. But the sharpened image isn't necessarily closer to the truth. That's because you may end up making something sharp in the image that was actually not sharp in the real world; and also because you sharpen the noise which makes the image noisier.

Iain West
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BJL
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« Reply #24 on: August 30, 2005, 06:37:38 PM »
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As long as dynamic range is not objectionably compromised by doing so
As I understand it, the problem is 'read out' noise.
I am not at all sure, but I believe that you are partly right; total "dark noise" is dominated by read out noise rather than sensor dark current noise, except in fairly long exposure times where dark frame subtraction becomes useful for cancelling part of the dark current noise.

However, it is not true that read-out noise is independent of pixel size: smaller photosites with smaller maximum electron counts seem to have less electrons of read-out noise; I suppose that smaller components with less thermal noise generation can be used in the read-out process. At a guess though, the read noise reduces more slowly than the maximum well capacity, so S/N ratio gets a bit worse with smaller photosites.

Digicam photosites as small as 2.5 microns are far from overwhelmed by read-out noise, so DSLR photosites can be shrunk a lot before being too small to be useful on that count. I expect lens resolution limits will bite first.

Read-out noise does set both upper and lower limits on frame read-out rates, so that extremely high pixel counts could be stranded "between the devil and the deep blue sea". Read too many pixels per second and the noise gets worse, but if read-out takes too long, noise also increases. (Maybe dark current keeps accumulating so long as the "signal" stays in the electron wells of the sensor.)

But there are possibly ways to improve this situation, such as the four channel system used in the Sony sensor of the Nikon D2X, which ensures that at least part of the read-out process only has to go one quarter as fast. Maybe this can be extended to ever more parallel read-out channels.
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Jack Flesher
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« Reply #25 on: July 16, 2005, 11:02:58 AM »
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All I can say is that now I really want one.

Let's see...  An H1, five lenses and the P45...  Can I get $50,000 for my left kidney?

,
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Paulo Bizarro
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« Reply #26 on: July 17, 2005, 12:45:32 AM »
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Yesterday I have dropped by the local lab to collect my latest "hang from the wall" framed photo. It is a panorama made up of 6 photos shot with the Powershot Pro1, and stiched with the Canon software. Quite simple.

The final assemblage is 85 cm long and 20 cm wide. It looks great on my wall. I think the end game depends a lot on what you want/require, either comercially (if you make a living out of photography), artistically (if you shoot for fine art), or just for the #### of it.

The end game is the print.
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lepingzha
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« Reply #27 on: July 17, 2005, 03:13:08 PM »
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The differential factors are:

1. Subjects. In studio digital is fine. With a lot of low
  contrast foliage in landscapes digital simply breaks
  down by their low-pass filtering and noise reduction
  (especially with Canon).

2. Printing size. At 13x19 there is little difference to
  95% of viewers (although not me), but at 30x40
  those of digital origin are full of artifacts whilethose
  from 4x5 film originals can still beexamed with a
  magnifying glass for details from the long tile of
  the film's extended MTF curve.

For those who debunk ClarkVision's science, why do
they take a look of the comparison images Clark
dutyfully provided? Pictures says more than the
math.  One more study with image comparison
can be found at:

http://www.kenrockwell.com/tech/filmdig.htm

Even in Michael's 1Ds vs. Pentax 67II examples,
where he said the digital has more resolution, anyone
with an unimpired eyesight can see the scanned
chrome provide much more details where the digital
is all artifacts along the high contrast edges of the
buildings and windows (notice the horizontal line at
the 2/3 window height from the bottom completely
missing in the digital captured?)  To me it shows
that the P67 chrome showed at least 3x more
resolution obviously in Michael's very own
comparison.  His arguments that "the 1Ds frame
above appears to have lower resolution because
it is a MUCH bigger enlargement" is simply a way
of stating "the digital file can NOT be enlarged as
big or all you see are the artifacts".

Noise is another matter.  Many $20K audiophile CD
players add noise for more natural sounding.  Someone
added little noise to a D2x file in a DPreview discussion
a while ago to make it much better looking.  Too little
noise in landscape and nature photography creates a
sense of steadiness, unnatural and lack of depth or
dimensionality.  Again it is subject dependent.  I pity
those who never experienced the detailed LP sound
off a good system.  The human ears are not linear
Fourier analysers, so that although the pure 80k tone
can not be heard directly it can contribute to make the
sound (air pressure) wavefrount much sharper, to
enhance the impact from a hit of the drum or bass
string even the harmonic's amplitude is very low.

Leping Zha, Ph.D.
www.lepingzha.com
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Jonathan Wienke
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« Reply #28 on: July 18, 2005, 10:28:53 AM »
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This is a myth perpetrated by the Foveon crowd. A Bayer array does NOT lower resolution a factor 3x, EXCEPT if you are imaging in primary blue or primary red. With any normal, mixed color subject or lighting there is remarkably little loss of resolution.
That matches my experience also; the only time Bayer-pattern sensors aren't perfectly capable of resolving single-pixel detail is when the colors involved are so saturated that you have adjacent pixels clipping to minimum and maximum values simultaneously. This image has plenty of single-pixel sized detail, and is a 100% crop from a portrait shot with the 1Ds:



Look particularly at the pores on the back of her left hand, the threads in her blouse, and her eyebrows and eyelashes. This image has had my normal midtone sharpening performed on it, as well as a Focus Magic pass at radius 2, strength 75%. The Focus Magic pass does an excellent job of reversing the effects of the anti-aliasing filter and really bringing out the detail without introducing artifacts.
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dwdallam
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« Reply #29 on: July 18, 2005, 03:11:32 AM »
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All I can say is that now I really want one.

Let's see...  An H1, five lenses and the P45...  Can I get $50,000 for my left kidney?

,
I'd rather wait a couple years, save the kidney, and get it for 10K. Prices are dropping fast on high end digitals it looks like. Well, maybe not that high end, so you got me there. But at least for the DSLRs of the professional qualities that were 6K two years ago.
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lepingzha
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« Reply #30 on: July 18, 2005, 07:58:42 PM »
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I quit, since:

1. Nobody sees the artifacts everywhere along the
    edges and over the hairs.  Charles Cramer and
    Bill Atkinson, two of my mentors in digital printing,
    never use sharpening radius over 0.4, while the
    image was doen at least with 1.0.   If everybody
    says this is a good image of course you all have
    your rights to enjoy your good taste and there
    are problems in my eyes which make them to see
    those thin lines in the window in the Michael's
    film scan that the digital completely missed.

2. Remember this is in a landscape discussion group
    not supposed to deal with studio shoots like this,
    which favors digital capture from the start.

3. The Bayer based digital pixel values are NEVER
    true representation of the lights the sensors see.
    They are merely mathematical estimats, or well
    conditioned guesses, depending on the algorithm
    in the raw convertor.

Thanks to all involved,
Leping Zha, Ph.D. in Physics
www.lepingzha.com
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Ray
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« Reply #31 on: July 18, 2005, 10:07:19 PM »
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All Jonathan's image tells me is that one has enormous post-capture latitude with image processing to make them look as "film-like" or "digital-like" as one wants
Quite so. Now all I ask of technological development in the near future is that they provide me with an affordable desk top scanner with the performance of a $50,000, 10,000 dpi drum scanner, an ICE program that removes scratches from Kodachrome and sliver based B&W negatives without reducing fine detail in any shape or form, and the same thing for grain reduction technology.

Now that's not too much to ask for, is it?  Cheesy
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Jonathan Wienke
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« Reply #32 on: July 19, 2005, 02:01:15 AM »
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I only mentioned that to my eyes the added noise made
the image look more natural. This has nothing to do
with the general quality of DPreview forum discussions,
to anyone with a sound sense of logic. At least nothing
was labeled "bull" in the DPreview forum...
If you truly think that one must add noise to an image (or an audio recording) to make it "natural" then your idea of "natural" deviates from the commonly accepted norm. When I'm listening to someone playing a harp, I don't hear white noise, so I see no reason to add it to aan audio recording to make it more "natural". When I'm looking at a landscape scene, I don't see film grain patterns or sensor noise artifacts, therefore adding or celebrating such things in recorded images has nothing to do with "natural". At best it's disguising the presence of one type of artifact by adding a less objectionable form of artifact to cover up the first artifact, but such an act cannot possibly make the result more "natural", it can only make the image deviate even further from the original scene than before.

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However for Velvia it is very different.  What
made me speak was nothing but Michael's stretch that
the P45 will beat scanned 8x10 in all cases.  Again this
is a discussion group of landscape photography, and
over 90% of the film based landscape photographer
shoot chromes not negatives.

Velvia is not magic. And Michael said the P45 "will become a object of desire for any photographer looking for what will likely be almost 8X10" sheet film quality", not that the P45 "will beat scanned 8x10 in all cases". Those are two distinctly different things; you're fabricating a strawman argument here.
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BernardLanguillier
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« Reply #33 on: July 19, 2005, 10:29:28 AM »
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How could I not think about it myself...

Cheers,
Bernard
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A few images online here!
Ray
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« Reply #34 on: July 19, 2005, 08:29:53 PM »
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I thought it had been well established that 9 million Foveon photosites are equal to 6 million Bayer type photosites, ie. the 3 megapixel SD9/10 produces an image quality roughly equal to a D60 or 10D, including resolution.

Why do we not yet have a 6 megapixel Foveon based camera which should theoretically equal the performance of a Nikon D2X? I can only presume it's because of some inherent design weakness that's too difficult to overcome, namely noise at high ISOs.

The trend is clearly towards more useable high ISOs, with Canon raising the bar with each new model. Having 2 additional sensor layers that some of the light has to pass through must weaken the signal to some degree.
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Mark D Segal
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« Reply #35 on: July 20, 2005, 08:43:40 AM »
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For sake of better understanding, I decided to revert to the fundamentals underlying the discussion about Foveon versus Bayer striped array, so I went back to Bruce Fraser's "Real World Camera Raw with Adobe Photoshop CS" and re-read chapters 1 and 2, where all this is discussed in some detail. What I retained from this review are the following propositions (liberally interpreted by me):

(1) Each photosite captures one pixel of colorless information, and the more bits per pixel, the more the editing headroom before information gaps become noticeable.
(2) Pixels only deliver resolution when dimensioned, the more the PPI the smaller the pixels and up to a limit the better the apparent image quality.
(3) Pixels are assigned colors by filtering. Foveon differs from stiped Bayer array by layering the color filtering instead of arraying it.
(4) The main difference (3) makes is that Bayer array data needs to be demosaiced in the RAW converter but the Foveon data does not.

What I deduct from the above four points is that (a) methods of assigning color to pixels (items 3 and 4) should not bear any necessary relationship to the factors determining apparent resolving power attributable to the capacity of the sensor (items 1 and 2), and ( by inference from material on page 5 of the same reference, Foveon may have some advantage producing more accurate color rendition (not more resolution) in those cases where the detail is only captured on one pixel in a Bayer striped array filtered to one of the three primaries, making accurate color rendition difficult. The frequency of these situations would seem to be small based on the observation that color rendition from Foveon chips appears no better, and indeed probably not as good as that from today's non-Foveon CMOS sensors on professional DSLRs.
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Mark D Segal (formerly MarkDS)
Author: "Scanning Workflows with SilverFast 8....." http://www.luminous-landscape.com/reviews/film/scanning_workflows_with_silverfast_8.shtml
Ray
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« Reply #36 on: July 20, 2005, 11:47:15 PM »
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This is pixel peeping to the Nth degree. That's fine with me. Just bear in mind that the final results on the print will probably ignore most of the subtleties discussed, and if they don't, our eyes will.
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Jonathan Wienke
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« Reply #37 on: July 21, 2005, 01:04:14 PM »
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It would appear to my un-informed ears that the lossless compressibility of an image is not by itself a proof of the existence of a gap between data and actual information.
You may find these references useful reading:

http://szabo.best.vwh.net/kolmogorov.html
http://hornacek.coa.edu/dave/Tutorial/notes.pdf (applicable section starts at 1.2.6, LOTS of advanced math)
http://photonsstream.net/
http://www.google.com/Top...._Theory

If you read up on information theory, you'll discover that not only is this indeed the case, but it is provable to the point of being axiomatic. Whether it is the result of a degree of uniformity or redundancy in the image data (which is always the case in real-world images) or some other factor is irrelevant. The legitimate presence of patterns or uniform areas in an image still reduces the amount of information required to describe the subject with whatever level of accuracy you choose to specify.

Lossless compression by definition has a 1:1 mapping between input and output; for any output, there is only one possible input. All that is happening during lossless compression is that redundancies in the input data are being restated using the fewest bits possible in the output. The ratio between the number of input bits and output bits (given an efficient compression algorithm) can be used to measure the amount of actual information present in the source data.

If you make a photograph of a section of perfectly smooth green wall that is perfectly evenly illuminated with a camera that has a perfectly noise-free sensor, the resulting RAW file will only contain a very small amount of information, something along the lines of "make a rectangle composed of X by Y pixels with this RGB value in this color space". Given efficient lossless compression encoding algorithms optimized for RAW data, no matter what the resolution of the camera, the RAW data could be losslessly compressed to a few kilobytes. No matter how much data you use to describe that small amount of information, the amount of actual information is constant.

Real-world RAW files are not so easily compressible, as there is a lot more information to deal with. Subjects have detail which requires a minimum amount of information to describe with an acceptable margin of error, lighting is not perfectly uniform, and some bits of information are always wasted describing the details of that frame's sensor noise pattern or film grain. But you can still use lossless compressibility to measure the actual information content of the RAW data, as long as you keep in mind that the compression algorithm cannot distinguish sensor noise from true image detail and so some of the information that survives compression is useless noise.

Now for a practical application of all this theory: I decided to use lossless compressibility to attempt to quantify the amount of actual information in a true RGB image as opposed to a Bayer interpolated one. Here's what I did:

1. I shot two photos of a brick wall with my 1Ds on a tripod wearing the 70-200/2.8L IS, one at 70mm, and the other at 200mm, converting both with matching ACR settings.

2. I made matching crops from the center of the image, and downsized the 200mm crop to match the 70mm crop pixel-for-pixel, using Photoshop CS2 Bicubic. Given that there are over 8 source pixels for each destination pixel in the reduced crop, the Bayer interpolation and anti-aliasing filter effects are pretty well canceled out, and comparing these two crops is about as apples-to-apples a comparison as is possible. Here they are:

Straight Bayer 1Ds 70mm crop:


And the size-reduced, simulated-Foveon 200mm crop:


Except for RAW conversion, and the bicubic resizing of the second crop to size-match the first, no other image edits have been done.

3. I saved both images as losslessly-compressed JPEG200 files. As expected, the simulated-Foveon image is larger; 914KB vs 826KB for the straight Bayer crop. If my methodology is valid, that would indicate that a true RGB sensor such as the Foveon) would capture about 10% more real image information for this particular subject. That seems a bit low looking at the unprocessed files; the uninterpolated RGB image appears to have much more detail than the Bayer interpolated one. Therefore,

4. I applied a Focus Magic sharpening pass to both images to try to make each of them look as good as possible:

Straight Bayer (radius 2, amount 125%):


Simulated-Foveon (radius 1, amount 50%):


The difference has decreased somewhat, though it is still there. The main difference is a somewhat subtle "artifacty" look to the upper-right quadrant of the straight Bayer crop that looks more natural and detailed in the simulated-Foveon crop.
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Jonathan Wienke
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« Reply #38 on: July 21, 2005, 06:51:55 PM »
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OK, perhaps I misunderstood your original point then. I think perhaps we're on the same page, but just saying things in different terms.
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Big Bird
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« Reply #39 on: August 16, 2005, 10:21:57 PM »
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This is an interesting discussion, here are my thoughts. I think in terms of MP, we are near the "end game". Profitability is determined by selling a product to a lot of customers. The average consumer is definitely there, as the average person hardly ever wants a print bigger than a 4x6, let alone needing a 13x19 upwards.
The average consumer will drive this thing, the so-called "advanced amateur"/Professional, will essentially live with the end result. Market position of the companies at the stabilization point is the goal, I think of the manufacturers at this point.

My 2 cents.
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