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Old Jun 6, 2006, 12:36 PM   #41
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NHL wrote:
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A 'grain' is analog - you can have as many level as you want (This quantization varies depending on the # of bit from the A/D)
-> Remember you used to be able to "push" by varying the process time... (or temperature)!
I don't understand the chemistry behind it, and I always assumed film was analog.

But, Michael Reichmann is saying otherwise:

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Grain particles are binary. An individual film grain can only be either black or not-black, on or off, exposed or not exposed. Sort of a binary device. A photo site (pixel), on the other hand, has a range of thousands of brightness levels, because it's an analog device. (Curious isn't it, that at this level film is binary and digital is analog?)
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What this means is that it takes a clump of between 30-40 grains of film to represent a full tonal range, (similar in concept to the dithering done by inkjet printers to produce continious tones), while on a sensor each individual pixel can reproduce from hundreds to thousands of tonal levels.
[align=left]
http://www.luminous-landscape.com/essays/clumps.shtml

[/align] So, if he's right, the chemistry is just turning on/off more or fewer grains based on exposure and processing.

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Old Jun 6, 2006, 4:01 PM   #42
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A couple of other things occur to me:

1. Perhaps the reason no-one really noticed the deficiencies of the wide-angle L lenses before was that overall image quality from 35mm was not such that there were very many landscape photographers using it. In general they were using medium format. Now that overall image quality (being a combination of noise and resolution) has the 12-17Mp cameras competing with medium format film more photographers who were previously shooting medium format are now finding that the Canon wide-angle lenses aren't up to the job.

2. From an 8Mp camera you get 8 million interpolated pixels. How many real pixels? Well that all depends on how good the interpolation algorithm is. Somewhere short of 100%, but exactly how far short is critical to image quality. And how well a particular algorithm works is at least partly related to the subject matter.

So we have the claim being made that film is very good at showing up resolution on charts and general colour resolution will in fact be lower, whereas digital isn't giving the full number of true pixels you might expect, there are errors in there. So it may be that depending on the subject one is better than the other.

Overall image quality is of course the combination of resolution and noise.

But also it seems very clear that i.t.o. overall image quality the 6-10Mp cameras are essentially as good (in general) as 35mm and that the 12-20Mp are as good (in general) as medium format film. And now the claims that the new MFD 39Mp backs are about as good as 5"x4" film.

I think there are plenty of links that I find credible to support the above claims. Not that I operate in the expensive realm at this point, but I do see a 5D on my horizon.


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Old Jun 6, 2006, 9:47 PM   #43
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JimC

I'm quite neutral in all this and not try to prove anyone right or wrong...

Just the article is over simplistic - an emulsion layer is quite thick, up to 10 microns sometime, so it's not just one grain in thickness unlike a CCD or CMOS sensor. A color film has a minimum of three layers (very much like a Foveon sensor), with some color film from Kodak going as thick as 12 layers!

I'm already a 'digital' convert... But sometime I'm still quite amazed at how theses CCD's or digital processors are still made - The chemical photographic way:

http://pages.unibas.ch/phys-meso/Edu...thography.html
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Old Jun 7, 2006, 9:32 AM   #44
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Peripatetic, can you refer me to a source for your image quality info? I have not seen a statement that a 16MP 24x36 sensor had resolution comparable to medium format film. All I've ever seen suggested that the Canon 1DsMkII was close to 35mm film but not quite there yet.

style="BACKGROUND-COLOR: #000000"The guy that started this thread has probably given up now that it has been officially hijacked from his search for a general purpose zoom under $500.
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Old Jun 7, 2006, 9:56 AM   #45
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Here is an old article comparing a 3MP Canon EOS-D30 to Fuji Provia 100F:

http://www.luminous-landscape.com/re..._vs_film.shtml

Here is another old article comparing a 6MP Canon EOS-D60 to Medium Format (645):

http://www.luminous-landscape.com/re.../d60/d60.shtml

Of course, you'll also find articles claiming that a much higher pixel count is needed, and that the test results are skewed because of limitations of the scanning and printing process.


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Old Jun 7, 2006, 10:02 AM   #46
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wburychka wrote:
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The guy that started this thread has probably given up now that it has been officially hijacked from his search for a general purpose zoom under $500.
You're right (and I should know better since I'm a moderator).

So, I'll close this thread so that the original posters don't keep getting notified about new posts to a thread that's taken a different direction.

If anyone wants to continue the film versus digital discussion, just start a new thread.

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Old Jun 9, 2006, 10:55 AM   #47
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This thread is now open for posts again. But, please keep responses in this thread limited to the original poster's concerns (general purpose zoom lens under $500).

A new thread was started by peripatetic to continue the film versus digital discussion (so let's use it for that purpose):

http://www.stevesforums.com/forums/v...mp;forum_id=65

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