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Ray
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« Reply #100 on: February 28, 2007, 06:26:32 PM »
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In his experiments Roger did expose the medium to saturation, effectively exposing to the right. His saturation exposure for the negative film was +1 EV, which is less than I would have imagined, but that is what he got with the Kodak Gold 200. That film is no longer made, but in the data sheets for Kodak's newest Portra professional films, I note that the characteristic curve is linear up to a DMax of about 2.0 for green light; there is no shoulder.

When I used to scan film, I always preferred transparency film (Velvia, Provia, Kodachrome) to negative film, since I always found the grain to be excessive with negative film.

Bill
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Of course, this is why it's very difficult to make general statements about film. You usually have to be specific. Which film? They've all got different characteristics. The situation is also complicated by the type of developer used.

Can we just say, Roger Clark has tested the DR of Royal Gold 200 and found it to be rather underwhelming. A test of one film type should not be cause for a general statement. My statement was of a general nature based on experience with a number of low ISO negative film types, usually ISO 100 but also Royal Gold 25 until it was discontinued. I've still got some rolls of Royal Gold 25 in the fridge, which I'm reluctant to throw away.

I'll also repeat, I was never able to get good detail in deep shadows (from color negative) without performing dual scans. I notice that Roger mentioned he would visually inspect the negative before scanning and that the scan would contain slightly more detail than he could see on the negative. I'd question this procedure.
« Last Edit: February 28, 2007, 06:42:34 PM by Ray » Logged
Ray
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« Reply #101 on: February 28, 2007, 09:41:52 PM »
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Just to hammer the point home, I'll give some examples of my experiences which lead me to believe that color negative has no worse DR than a DSLR and possibly better in real, practical terms. Unfortunately, I have not compared the identical scenes, so I admit my methodology is flawed in this respect.

The following shot was taken with Kodak ISO 100 film. It was so long ago I can't remember if I used a tripod or relied upon IS. The general lack of 'tack sharpness' would suggest I didn't use a tripod.

[attachment=1948:attachment]

If I'd taken this shot with a 5D, I would expect to see unacceptable noise in the dark foreground when adjusting the images as follows.

[attachment=1949:attachment]

A few days after buying my 5D and 24-105mm lens as a package, I discovered on the net there was a known flare problem with the lens. The following shot was an attempt to discover the flare problem. I didn't succeed and have since never come across any flare problem that doesn't look like normal flare from any lens.

However, what I did discover in this experiment was a disappointing shadow performance of the 5D at ISO 100. At some point, the image becomes very degraded in a manner which I haven't seen with color negative film.

Below is the 5D shot I'm referring to. Conversion was minus 1.5EC to recover blown highlights. That wasn't possible. The brightest spots are completely blown. There's nothing blown in the negative scan. There's nothing that's 255,255, 255. There's nothing that has even a single 255, and there's nothing that has a 233, 233, 233, or 244, 244, 244, or 254, 254, 254 etc. I take that as meaning; no blown highlights in the negative scan.

The following shot was converted with shadows at zero, EC at minus 1.5 and contrast at minus 50.

[attachment=1950:attachment]

The adjusted image is going to leave some substantail areas dark, not only for esthetic reasons but also because shadow detail is crap.

[attachment=1951:attachment]

What's detail like in that dark band of foliage stretching across the middle right? Not too good.

[attachment=1952:attachment]

To summarise.

1. The scenes are different although similar in light intensities. Definitely a flaw in methodology there.

2. However, the film scan has no blown highlights. The 5D shot does, despite a minus 1.5EC correction.

PS. Forgot to mention. If anyone's interested, the film scan shot is of Cunningham's gap, not far from my studio, SE Queensland, Australia. The inferno on the right is probably where I'll go when I die. (Just joking! I kid myself I'm destined for heaven   ).
« Last Edit: February 28, 2007, 09:48:51 PM by Ray » Logged
Kirk Gittings
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« Reply #102 on: February 28, 2007, 10:01:52 PM »
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FWIW

I'm not at all sure about theoretical aspects of this, but the last few years before switching to digital, I shot LF color negatives extensively (scanned thousands of them) in my business for clients that just wanted files. I prefered them because they clearly had a greater usable DR than any of the transparency films out there, though they were more work. I use Fuji films almost exclusively, NPS then 160 ProS and Provia and Velvia for magazines.

While transparencies scanned easier ,ie is it was easier to extract what was in the transparency vs. extracting the full potential of a neg. There are still issues of adequate profiles for color negatives because of the mask. All scanners are calibrated with transparencies (IT8) and the supplied profiles were always more accurate and consistent with transparencies as a result. Negative profiles always had to be tweaked much more than Trans. Negatives had more dynamic range potential but it was allot of work to extract it. Through experience we worked out how to do that. One of the big issues with CN was exposure. CN profiles are very exposure dependent. Meaning that if you tended to shoot a 160 film at 100 as I do, you virtually had to reinvent the canned profiles. Having said all that from a business point of view color negs were still more cost effective, because of saved film and processing costs, because we virtually did not have to bracket exposures with CN. Sharpening is more of an issue with CN as UM tends to sharpen and acentuate the grain-not an issue with trans., but as we were shooting 4x5 it did not matter much. The guru of scanning color negatives is Danny BurkDan Burk a Lf landscape photographer who is a big advocate of CN.
« Last Edit: February 28, 2007, 10:15:45 PM by Kirk Gittings » Logged

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« Reply #103 on: March 01, 2007, 01:24:42 AM »
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If I'd taken this shot with a 5D, I would expect to see unacceptable noise in the dark foreground when adjusting the images as follows.


A few days after buying my 5D and 24-105mm lens as a package, I discovered on the net there was a known flare problem with the lens. The following shot was an attempt to discover the flare problem. I didn't succeed and have since never come across any flare problem that doesn't look like normal flare from any lens.

However, what I did discover in this experiment was a disappointing shadow performance of the 5D at ISO 100. At some point, the image becomes very degraded in a manner which I haven't seen with color negative film.


The adjusted image is going to leave some substantail areas dark, not only for esthetic reasons but also because shadow detail is crap.


[a href=\"index.php?act=findpost&pid=103926\"][{POST_SNAPBACK}][/a]

This reminds me of problems I have with my Canon 5D and I must say this is one reason why I looked hard at MFD, but the weight/cost issue is a problem for my kind of work.

I also encountered that the 5D has sometimes problems with for example a sky with sunset where it can happen that the sky gets a staircase effect, not a smooth gradiation (yes I use Raw with DXO and tiff 16 Bit).
And yes the shadows can be crap, but I tend to open up the shadows of a digital file more, than the shadows of a scan, so maybe this is not a fair comparison.

Is this just the Canon 5D or a general digital problem ? Any solutions ?

Christian
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Ray
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« Reply #104 on: March 01, 2007, 02:33:31 AM »
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This reminds me of problems I have with my Canon 5D and I must say this is one reason why I looked hard at MFD, but the weight/cost issue is a problem for my kind of work.

I also encountered that the 5D has sometimes problems with for example a sky with sunset where it can happen that the sky gets a staircase effect, not a smooth gradiation (yes I use Raw with DXO and tiff 16 Bit).
And yes the shadows can be crap, but I tend to open up the shadows of a digital file more, than the shadows of a scan, so maybe this is not a fair comparison.

Is this just the Canon 5D or a general digital problem ? Any solutions ?

Christian
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Never come across the staircase effect. Are you shooting RAW and converting into 16 bit ProPhoto?

The shadows can also be ugly with the 1Ds. If I'd given just half a stop less exposure to my above 5D example to reduce clipping of the highlights, the deep shadows would have been horrendous instead of plain awful.

Negative film has a broad shoulder. There's no sudden clipping as one overexposes. Likewise with the shadows. There seems to be a fairly even degradation of image quality where definition gradually becomes more and more obscured by grain. I guess this is why one can claim a 15 stop dynamic range for negative film. There's still some detail to be gleaned at each end of the spectrum.
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Ray
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« Reply #105 on: March 01, 2007, 03:02:06 AM »
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Perhaps we should be talking about this in the past tense. Negative film used to have a broad shoulder.  
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« Reply #106 on: March 01, 2007, 03:38:39 AM »
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My statement was of a general nature based on experience with a number of low ISO negative film types, usually ISO 100 but also Royal Gold 25 until it was discontinued. I've still got some rolls of Royal Gold 25 in the fridge, which I'm reluctant to throw away.
A friend of mine adored the clean images he got with Royal Gold 25, and was pissed when it was discontinued.

However, he's (so far) satisfied with the image quality of his 1D MkII, so he apparently wasn't enjoying Royal Gold 25 for its dynamic range as much as the generally clean images.
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« Reply #107 on: March 01, 2007, 05:11:24 AM »
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A friend of mine adored the clean images he got with Royal Gold 25, and was pissed when it was discontinued.

However, he's (so far) satisfied with the image quality of his 1D MkII, so he apparently wasn't enjoying Royal Gold 25 for its dynamic range as much as the generally clean images.
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Royal Gold 25 was my favourite film before I bought my first DSLR, the D60. I was also dismayed when the film was discontinued, so I bought a few rolls whlist I could still get them. That's why I've still got a few in the fridge.

I was not only impressed with the fine grain, but there was a quality about the color, hue and saturation that pleased me greatly. If I was into conspiracy theories, I would even suggest that Kodak discontinued this film in order to remove competition to its digital cameras.
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Ray
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« Reply #108 on: March 01, 2007, 06:27:46 AM »
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For some strange reason, Ektar 25, the slide film with presumably even finer grain than Royal Gold 25, was discontinued first. A short time after Kodak issued a sampler Photo CD disc with some Ektar 25 shots, I noticed at an exhibition in Brisbane a Kodak 6mp DSLR (Nikon body) for the trivial sum of A$40,000.

Of course, being a rational sort of person, my mind automatically stripped off a zero and I remember walking around looking at the rest of the exhibits thinking I might soon be able to afford one of those cameras.

The fact is, when some years later I saw sample images on Kodak's web site from their latest 6mp DSLR, they didn't seem (in my opinion) anywhere near the quality of these 18mb scans (now over 15 years old) on their sampler Photo CD disc.

Here's one which I like in particular. Taken by Bob Clemens, unfortunately.

[attachment=1954:attachment]

The texture of the skin is quite remarkable as can be seen in this 100% crop.

[attachment=1955:attachment]

Not bad for an 18mb scan, eh!?
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« Reply #109 on: March 01, 2007, 10:51:42 AM »
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You've missed the point, CatOne. I'm not recommending a return to color negative film. I'm just replying to Bill's refutation of my statement that I believed current DSLRs have around the same DR capability as color negative film. Bill, quoting his favourite authority, Roger Clark, claims this is not so.

It's not entirely a dead issue. There appear to be still some photographers shooting film because they believe, rightly or wrongly, that negative film gives them wider latitude and DR (according to a google search).
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Perhaps it's not entirely a dead issue, but those photographers who shoot negative film because digital doesn't have the same DR must enjoy the sand in their ears when they remove their head from the sand.

Practically, the solutions for shots that require 15 stops (lo, let's say 20 stops) of DR are rather straightforward, including:

* Don't take the shot in the first place... it may be uninteresting
* Use a ND grad filter, if you have one, to compress dynamic range
* Take the shot twice with digital, and composite it (as you showed in your example above)

#3 takes someone with working knowledge of Photoshop about 2 minutes to do, to get a fine result (one that looks substantially more realistic than your composites from the hotel room).  To say that film with its wider shoulder gives a better DR is really a silly argument, because you are artificially constraining what's allowed simply to make film "win" the judgement.  The outcome is predicating the test and the "rules" to justify a certain conclusion.

Plus, if the 1D III (that is what this thread is about, after all), truly does have 1 or 2 stops  more DR than the 5D then perhaps the shadow details would be better.  Still, in a shot with > 8 stops of DR, if you're going to pull the shadows from zone 2 to zone 4, I'd argue the results would be better with a composite.
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« Reply #110 on: March 01, 2007, 10:53:05 AM »
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...

Not bad for an 18mb scan, eh!?
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I'd argue it could use some color work, or perhaps the converse is that I don't like the palette that films of 2 decades ago provided, as I assume that's the color they intended it to be  
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bjanes
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« Reply #111 on: March 01, 2007, 11:23:54 AM »
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Of course, this is why it's very difficult to make general statements about film. You usually have to be specific. Which film? They've all got different characteristics. The situation is also complicated by the type of developer used.

Can we just say, Roger Clark has tested the DR of Royal Gold 200 and found it to be rather underwhelming. A test of one film type should not be cause for a general statement. My statement was of a general nature based on experience with a number of low ISO negative film types, usually ISO 100 but also Royal Gold 25 until it was discontinued. I've still got some rolls of Royal Gold 25 in the fridge, which I'm reluctant to throw away.

I'll also repeat, I was never able to get good detail in deep shadows (from color negative) without performing dual scans. I notice that Roger mentioned he would visually inspect the negative before scanning and that the scan would contain slightly more detail than he could see on the negative. I'd question this procedure.
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Roger's scanning methods are not well documented, but he did specify that they were 12 bit. The dynamic range noise floor for Kodak Gold was high due to grain. The DR noise floor for Royal Gold 25 could conceivably be better, but we have no data.

We gan get some information from the characteristic curve of the referenced films. I will consider only the green response.

Royal Gold 25
[attachment=1958:attachment]

The log exposure range is -1.84 to +1.6, for a total range of 3.44 logs. The luminance ratio would be 10^3.44 or 2754:1, or about 11.4 f/stops. Therefore, the maximal DR of this film is 2754:1, not considering noise, which would lower the effective DR. Of course, you could claim that Kodak could have extended the exposure scale to capture DR not shown in the characteristic curve. However, manufacturers do not typically understate the merits of their product, and the limits of the toe and shoulder are apparent in the published curve.

Gold 200
[attachment=1959:attachment]

The log exposure range is -2.9 to +0.8, for a total range of 3.7 logs or 5011:1, 12.3 f/stops not taking noise into consideration. This DR is actually better than Royal Gold 25, but would be degraded by noise in practice.

According to Roger's [a href=\"http://www.clarkvision.com/imagedetail/evaluation-1d2/index.html]Table 1a[/url], the DR of the Canon D1 M1 is 3190:1, with the noise floor 1 SD above the read noise. Looking at Roger's Figure 10, we see that the noise of the Canon 1D M2 is much better in the shadows of the film. You can say Roger's noise figures for the film are way off, but from the characteristic curve of the film, the DR can be no greater than 5011:1. Also note that Roger's response curve is similar to that shown in the Kodak data sheet.

I don't think the DR of Royal Gold 25 is quite up to your fond memories of it.

Bill
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bjanes
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« Reply #112 on: March 01, 2007, 11:36:53 AM »
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Just to hammer the point home, I'll give some examples of my experiences which lead me to believe that color negative has no worse DR than a DSLR and possibly better in real, practical terms. Unfortunately, I have not compared the identical scenes, so I admit my methodology is flawed in this respect.
[a href=\"index.php?act=findpost&pid=103926\"][{POST_SNAPBACK}][/a]

I suspect that the dynamic range of the scene in your 5D photo was most likely considerably higher than that of your film shot, and you have identified the flaw in your comparison.

Actually, the shadow noise characteristics of the 5D are far superior to film as brought out previously in this thread.

Bill
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bjanes
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« Reply #113 on: March 01, 2007, 11:40:10 AM »
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I'd argue it could use some color work, or perhaps the converse is that I don't like the palette that films of 2 decades ago provided, as I assume that's the color they intended it to be 
[a href=\"index.php?act=findpost&pid=104007\"][{POST_SNAPBACK}][/a]

As I recall, that PhotoCD image was used by Bruce Fraser in one of his books to illustrate how to remove a blue cast in the skin tones.  

Bill
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bjanes
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« Reply #114 on: March 01, 2007, 12:44:32 PM »
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Having attempted a google search on the dynamic range of color negative film, I'm beginning to have doubts if any DSLR can match the DR of color film.

There's a dynamic range test of Fuji Real 100 by someone at the University of Melbourne who gives it a theoretical DR of 15 stops. There's always going to be a subjective element as to just how useful the information might be in a particular stop at the extremes of the range. Some sources quote a theoretical DR of 20 stops for (presumably the best) color films. Digital sensors also have a theoretical DR, sometimes quoted by the manufacturer, but I've never seen figures as high as 15 stops.

The link to this experiment is http://www.path.unimelb.edu.au/~bernardk/t...hdri/index.html
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The experiment is interesting, but I think that a flaw in the author's method is that he is detecting very small changes in the response in the shoulder of the curve by averaging hundreds of pixels in his large tone patches in order to detect a significant change in pixel value.

For a high resolution picture, we are interested in changes of density over a much smaller interval (as "my  favorite author" pointed out in his post). I would be interested in some real high resolution images from this shoulder area to see if this "dynamic range" is useful. Roger's analysis of the film was mainly concerned with shadow noise limiting the effective DR floor. He did state that if he measured the signal over a large area of the target so that many film grains could be averaged, the DR floor could be extended, but that small detail would be lost in the noise.

Bill
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bjanes
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« Reply #115 on: March 01, 2007, 02:43:29 PM »
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For some strange reason, Ektar 25, the slide film with presumably even finer grain than Royal Gold 25, was discontinued first. A short time after Kodak issued a sampler Photo CD disc with some Ektar 25 shots, I noticed at an exhibition in Brisbane a Kodak 6mp DSLR (Nikon body) for the trivial sum of A$40,000.

Of course, being a rational sort of person, my mind automatically stripped off a zero and I remember walking around looking at the rest of the exhibits thinking I might soon be able to afford one of those cameras.

The fact is, when some years later I saw sample images on Kodak's web site from their latest 6mp DSLR, they didn't seem (in my opinion) anywhere near the quality of these 18mb scans (now over 15 years old) on their sampler Photo CD disc.

Here's one which I like in particular. Taken by Bob Clemens, unfortunately.

The texture of the skin is quite remarkable as can be seen in this 100% crop.

Not bad for an 18mb scan, eh!?
[{POST_SNAPBACK}][/a]

Ray,

In my Google search I came across this [a href=\"http://www.debevec.org/Research/HDR/debevec-siggraph97.pdf]paper[/url] (figure Cool which contains an illustration of the Stanford University Memorial Chapel from a PhotoCD disc of a print film shot (film unstated) that has a very high dynamic range. I think I will have to rethink my previous posts, but I thought I would let you know about this.

By the way, what is wrong with Bob Clemens?

Bill
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Ray
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« Reply #116 on: March 02, 2007, 08:42:23 AM »
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Practically, the solutions for shots that require 15 stops (lo, let's say 20 stops) of DR are rather straightforward, including:

* Don't take the shot in the first place... it may be uninteresting
* Use a ND grad filter, if you have one, to compress dynamic range
* Take the shot twice with digital, and composite it (as you showed in your example above)
[a href=\"index.php?act=findpost&pid=104006\"][{POST_SNAPBACK}][/a]


CatOne,
You don't have to convince me of the benefits of shooting digital. I'm aware of the basic techniques and possibilities of blending images to increase dynamic range, even though I might not be as clever as you in knocking up a perfect blend in 2 minutes of Photoshop work.  

However, I'm not aware of any technique of getting acceptably good registration of hand-held bracketed shots. The automatic alignment feature in Photoshop's 'merge to HDR' seems less effective than manually repositioning the layers.

There are many situations when using a tripod is not practical. You might need to take a shot in a hurry and don't have time to set up the tripod. You might be in a situation where you are simply not carrying a tripod for whatever reason, or you might be in a situation where tripods are banned (as well as use of flash) as in many old churches and museums in Italy. Split ND filters are of limited use. They generally require something like a horizontal sky line stretching across the image or similar division.

However good the DR of modern DSLRs is, at base ISO it doesn't seem to have increased much during the past few years. The improvement seems to have been directed mainly at high ISO performance. If the 1D3 can manage a real additional stop of dynamic range at ISO 100, that'll be just great.
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« Reply #117 on: March 02, 2007, 09:32:07 AM »
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However good the DR of modern DSLRs is, at base ISO it doesn't seem to have increased much during the past few years. The improvement seems to have been directed mainly at high ISO performance. If the 1D3 can manage a real additional stop of dynamic range at ISO 100, that'll be just great.
[a href=\"index.php?act=findpost&pid=104202\"][{POST_SNAPBACK}][/a]

I wouldn't put too much hope in that.  The blackframe read noise of a mkIII 14-bit RAW at ISO 100 is 4.88 ADU.  Translated to 12-bit, that's 1.22, a modest gain over the ~1.26 of the mkII (and perhaps just a camera-specific thing; the gain could vary a little from copy to copy).  The mkII data goes up to about 3711 on the clipped specimens I've seen, and the blackpoint is 128, so there are about 3583 12-bit levels.  The mkIII RAWs I have clip at about 15280 and have a blackpoint of 1024, so they have about 14,256 14-bit levels, or about 3,564 12-bit levels.  Since ISO 100 doesn't even use close to full well, it should be linear right up to clipping, with no hidden extra highlights.

Now, that's DR by the more liberal definition of max_signal:noise_floor.  In the brighter shadows and midtones, if the camera is capturing more photons at the same absolute exposure, then you may very well see a slight improvement there, but note that it would take a collection of *4x* as many photons to halve shot noise at any arbitrary tonal level.  4x as many as the mkII would most likely be more than 100% of the photons available.

I am a skeptic by nature, and that is why I don't jump up and down over company announcements.  They rarely materialize in the way they are announced.  The increased DR that Canon talks about may be nothing more than "better" JPEG NR at high ISOs, conservative metering (leaving nmore headroom, but giving more noise), or the 14-bit data (which is working with too much noise to be of full value).

The 14-bit data may help indirectly, as it will force ACR to work on the RAWs in a deeper space than the 12-bit cameras, which may improve the banding removal.  If the line banding in previous cameras was caused by the ADCs, then perhaps this new line of ADCs will reduce banding.
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Ray
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« Reply #118 on: March 02, 2007, 10:51:09 AM »
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In my Google search I came across this paper (figure Cool which contains an illustration of the Stanford University Memorial Chapel from a PhotoCD disc of a print film shot (film unstated) that has a very high dynamic range. I think I will have to rethink my previous posts, but I thought I would let you know about this.

By the way, what is wrong with Bob Clemens?
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Bill,
Now that's what I'd call a technical article, but I'm not sure I want to go there. Too much mathematics   .

It's not entirely clear to me that the variations on the Chapel are just from one shot. Most of the article seems to be about blending multiple shots. However, that's exactly the situation which a DSLR cannot handle in a single shot; light pouring through a stained glass window in a church. One either sacrifices some highlights for the sake of reasonably clean shadows, or one exposes for the stained glass and accepts overly dark shadows. At least that's my experience.

I spent some time today reviewing such shots from my trip to Italy (where tripods and flash units are mostly banned), and got a few surprises. The high ISO shots seemed to have better shadow detail than the ISO 100 shots, taken in similar situations, but not identical situations, so I'm afraid it's not a scientific comparison. My general approach was, if I could get a reasonably fast shutter speed at ISO 100, I'd use it. If I couldn't, I'd increase ISO. This would tend to imply that the ISO 100 shots would generally be taken in better lighting conditions, so I'm at a loss to explain why shadow detail should be so bad.

Below are a few screen shots of the conversions in ACR, each followed by the processed image which attempts to bring out the shadows. None of the images have had any noise reduction applied apart from sometimes a 'luminance smoothing' of 25 in ACR.

[attachment=1965:attachment]  [attachment=1966:attachment]  [attachment=1967:attachment]  [attachment=1968:attachment]  [attachment=1969:attachment]  [attachment=1970:attachment]

As you can see, I don't think shadows could be much worse than this. It's true that I could have given slightly more exposure to some of these ISO 100 shots, but so I could have with some of the following shots ranging from ISO 800 to 1600.

[attachment=1971:attachment]  [attachment=1972:attachment]  [attachment=1973:attachment]  [attachment=1974:attachment]  [attachment=1975:attachment]  [attachment=1976:attachment]  [attachment=1977:attachment]  [attachment=1978:attachment]

What's wrong with Bob Clemens? I don't know him. It's just unfortunate that it was him behind the camera and not me   .
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« Reply #119 on: March 02, 2007, 12:58:06 PM »
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It's not entirely clear to me that the variations on the Chapel are just from one shot. Most of the article seems to be about blending multiple shots. However, that's exactly the situation which a DSLR cannot handle in a single shot; light pouring through a stained glass window in a church. One either sacrifices some highlights for the sake of reasonably clean shadows, or one exposes for the stained glass and accepts overly dark shadows. At least that's my experience.
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Ray,

On re-reading that article, I think that you are correct. Figure 8a was a straight shot of the chapel, and the remaining illustrations were rendered from the HDR radiance map using blended exposures. The dynamic range of that scene was 100,000:1. Fortunately, there is little need for digital photographers to wade through the math employed in the paper, which is directed largely to undo the non-linearities of film photography.

I agree with your assessment of exposure. There is no way to capture such a scene in one shot with current digital cameras.

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I spent some time today reviewing such shots from my trip to Italy (where tripods and flash units are mostly banned), and got a few surprises. The high ISO shots seemed to have better shadow detail than the ISO 100 shots, taken in similar situations, but not identical situations, so I'm afraid it's not a scientific comparison. My general approach was, if I could get a reasonably fast shutter speed at ISO 100, I'd use it. If I couldn't, I'd increase ISO. This would tend to imply that the ISO 100 shots would generally be taken in better lighting conditions, so I'm at a loss to explain why shadow detail should be so bad.
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Your explanation of the exposure factors seems reasonable, but it might be that the illumination inside the church of the first picture at ISO 100 with particularly bad shadow noise and banding was very low. The only way to know for sure would be to take spot readings from the stained glass window and the interior of the church and determine the contrast ratio.

In post-Christian Italy were there any locals worshiping in those churches or was everyone a tourist?    

Bill
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