Luminous Landscape misinformation
Posted: Fri Feb 11, 2011 1:22 pm
Sent to Michael Reichmann:
Referring to this page on your site:
http://www.luminous-landscape.com/essays/clumps.shtml
you make several misstatements of fact. I have corrected them (in bold)
Just as the aircraft designer simply looked at the bee's lift to weight ratio and said that they obviously can't fly, the self-professed photographic experts shoots a high resolution target and then proudly declares that film outresolves digital, and they have the shots to prove it.
Because it's true!
What's wrong with this picture? (Pun intended).
Here's what's wrong. A very fine-grain film has grain particles that are about 2 microns in size. A typical DSLR has individual pixels that are about 6 microns in size. Ergo, film should outresolve digital. Right?
Correct. Not to mention that the pixels are a group, that it takes several cells to create an image, with green, blue and red recorded in different locations.
Not so fast! Here's the catch that many testers trip over. Grain particles are binary.
Bullshit! A grain that receives more light develops to a larger size. Grains that are struck by less light darken only slightly, and the rest of the crystal is dissolved in the fixer.
An individual film grain can only be either black or not-black, on or off, exposed or not exposed. Sort of a binary device.
Again, false. See above.
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?)
Nonsense. No difference.
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.
Again, false. See above.
So now we photograph a resolution chart, which is high resolution black and white. There's a line, or there isn't a line. This gives film an advantage because each grain can record whether or not it sees something. Ergo, high resolution film is going to measure as having higher resolution than digital.
Because it is.
But unless your idea of a good time is photographing black and white resolution charts, and instead you'd rather photograph your cat, your children, a sunset, or a flower, film's theoretical advantage simply goes away in a puff of smoke.
False.
This is why the so-called web forum experts can convince some photographers that bumble bees can't fly... errr... I mean, film can outresolve digital.
The next time someone writes this nonsense, tell them they're wrong because of "vortex shedding".
Thought you'd like to know.
Know what? Digital images tend to look 'crisper' but have less actual detail. This is because the silver crystals are sensitive to light from all directions, 360 degrees. There is a scattering of light as it strikes the emulsion, and this is called irradiation. So, light bouncing around inside the film causes crystals to 'see' light from neighboring areas and record it, causing a slightly 'fuzzy' look. Sensor cells on a digital camera face forward and are less affected by light striking adjacent areas, but the gaps between the cells are much larger, so the detail is simply not recorded.
Referring to this page on your site:
http://www.luminous-landscape.com/essays/clumps.shtml
you make several misstatements of fact. I have corrected them (in bold)
Just as the aircraft designer simply looked at the bee's lift to weight ratio and said that they obviously can't fly, the self-professed photographic experts shoots a high resolution target and then proudly declares that film outresolves digital, and they have the shots to prove it.
Because it's true!
What's wrong with this picture? (Pun intended).
Here's what's wrong. A very fine-grain film has grain particles that are about 2 microns in size. A typical DSLR has individual pixels that are about 6 microns in size. Ergo, film should outresolve digital. Right?
Correct. Not to mention that the pixels are a group, that it takes several cells to create an image, with green, blue and red recorded in different locations.
Not so fast! Here's the catch that many testers trip over. Grain particles are binary.
Bullshit! A grain that receives more light develops to a larger size. Grains that are struck by less light darken only slightly, and the rest of the crystal is dissolved in the fixer.
An individual film grain can only be either black or not-black, on or off, exposed or not exposed. Sort of a binary device.
Again, false. See above.
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?)
Nonsense. No difference.
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.
Again, false. See above.
So now we photograph a resolution chart, which is high resolution black and white. There's a line, or there isn't a line. This gives film an advantage because each grain can record whether or not it sees something. Ergo, high resolution film is going to measure as having higher resolution than digital.
Because it is.
But unless your idea of a good time is photographing black and white resolution charts, and instead you'd rather photograph your cat, your children, a sunset, or a flower, film's theoretical advantage simply goes away in a puff of smoke.
False.
This is why the so-called web forum experts can convince some photographers that bumble bees can't fly... errr... I mean, film can outresolve digital.
The next time someone writes this nonsense, tell them they're wrong because of "vortex shedding".
Thought you'd like to know.
Know what? Digital images tend to look 'crisper' but have less actual detail. This is because the silver crystals are sensitive to light from all directions, 360 degrees. There is a scattering of light as it strikes the emulsion, and this is called irradiation. So, light bouncing around inside the film causes crystals to 'see' light from neighboring areas and record it, causing a slightly 'fuzzy' look. Sensor cells on a digital camera face forward and are less affected by light striking adjacent areas, but the gaps between the cells are much larger, so the detail is simply not recorded.