Gear Talk > Technical Support
Dynamic Range War
unfocused:
Okay, I've noticed a lot of discussion (to put it politely) in other threads about the "dynamic range" of the new 5D III sensor. I'm hoping someone can enlighten me a bit and explain why or if I should care.
I'm not clear what exactly people mean by dynamic range. It seems like at least two definitions are possible.
1) Are you referring to the ability of the sensor to record detail in a scene that has a wide range of light. For example, are we talking about the ability to capture detail in a brightly lit canyon, where the light ranges from near total sunlight to near black. So that, a sensor that has a dynamic range of say "9" would be able to record detail for up to four stops from the midpoint in either direction?
2) Or, are you referring to the ability of the sensor to record discernible differences in light. For example, a range of "9" would mean that on a scale from black to white, there would be nine clear steps visible?
It's been many years since I read the Zone System (and frankly, I found the books excruciatingly boring), but as I recall Adams' basic premise was that film was capable of recording far greater dynamic range than could be reproduced by photographic paper (much less commercial printing). By manipulating exposure and development of the film, he sought to compress the dynamic range recorded by the film, so that it could be aligned with what the final print could reproduce. The general concept, as I recall, was to expose to retain some detail in the shadows and then develop to retain detail in the highlights.
My understanding is that photographic prints even today have less possible range than sensors and computer monitors less than prints. (Although the back lighting of monitors gives the appearance of greater saturation and richness in colors)
So, if I am wrong about this, can someone explain it in understandable terms. And, if I am right, then why should I care at all about dynamic range so long as the final medium is always going to be more limited than the medium used to capture the image in the first place?
dtaylor:
--- Quote from: unfocused on March 09, 2012, 10:53:00 AM ---1) Are you referring to the ability of the sensor to record detail in a scene that has a wide range of light. For example, are we talking about the ability to capture detail in a brightly lit canyon, where the light ranges from near total sunlight to near black. So that, a sensor that has a dynamic range of say "9" would be able to record detail for up to four stops from the midpoint in either direction?
--- End quote ---
This is what people mean when they say dynamic range. Though the mid point, i.e. the point where a gray tone is rendered middle gray, is not necessarily in the middle of the range. Digital sensors typically have more shadow range than highlight range, and print film typically has the opposite.
--- Quote ---My understanding is that photographic prints even today have less possible range than sensors and computer monitors less than prints. (Although the back lighting of monitors gives the appearance of greater saturation and richness in colors)
--- End quote ---
Monitors have more DR than prints. Some may even exceed sensors.
--- Quote ---And, if I am right, then why should I care at all about dynamic range so long as the final medium is always going to be more limited than the medium used to capture the image in the first place?
--- End quote ---
Because you can compress the captured range into a range that will fit on paper, and your viewer can see the shadow and highlight detail you saw at the scene. More DR also covers more exposure errors.
On that note...I don't know why anybody is talking about 5D3 DR yet. To my knowledge there are no published transmission step wedge tests of the 5D3. DPR is the site which usually does this first. You can safely ignore any and all claims based on noise measurements (i.e. DxO and personal estimates made from available RAW files). Trying to compute DR from the noise floor does NOT result in an accurate measurement of sensor DR in the real world.
awinphoto:
Hey unfocused... your definitions are both correct to a discernible degree... Yes, the downfall in photography, DR range was/is printing... film had a few more stops than photographic paper back in the day... I think film, especially negative film, had closer to 9 stops give or take (slide film had anywhere from 11-13 if i'm not mistaken but it's been quite a few years). Photographic paper at the time had like 5-6 stops of DR, so the zone method was created to leverage the developing process, exposure process, and printing to get the most maximum range out of papers limitations. It was an entire class in itself... a lot of math and testing and experimenting.
Now with digital, we are once again limited by CMYK and printing... The RGB color gamut is vastly wider than CMYK and commercial printing has not been able to catch up and there is really nothing you can do about it without adding spot colors and such... Modern epson and HP printers have even added Red inks and Orange inks and i think even blue, not to mention light cyan, light magenta, etc... all trying to get the widest gamut possible. Commercial printers have yet to catch on to do something similar without really adding to the cost of production.
Now regarding dynamic range, it is the level of stops and subtitles that you see throughout the entire range of the print... DR is best seen as an S curve... most cameras can get most of the middle ranges but struggle getting the information in the extreme highlights and shadows in which the DR range gets elongated and such. The 5d2, for example had a DR, depending on the testing source, of around 11-12 stops of DR. I would guesstimate most consumer digital cameras out there on the market today should capture around 9-10 stops of DR easily if not more. Now the question remains, if nikon/canon/sony/phase one, etc develop a sensor that could capture 13,14,15 stops of DR, most of it, as mentioned above would be in the subtleties in the highlights and shadows, but whether any would show up in print is another thing. Of course with the increasing development of digital frames, projectors, HD monitors, etc... you can make a good presentation, but for professional photographers delivering paper prints to clients, until not only cameras but printers/ink/output/cmyk development continues as well, it really is a futile argument.
Edit... epson a few years ago came out with the R2800 which was supposed to give more DR by having multiple black/gray inks to give more definitions in subtle tones, as well as give cleaner B&W prints without any color tinting that was prevalent in standard B&W inkjet printing... While successful, It also struggled in the color part because where they added in blacks and gray inks, they took away in color inks to compensate... now they have the R2880 and the R3000 which is trying to blend the technologies... It's still a work in progress however these printer companies update their printers almost less frequently than the 1d series does and commercial printing really hasn't changed a whole lot in the last half decade.
Larry:
--- Quote from: unfocused on March 09, 2012, 10:53:00 AM ---if I am right, then why should I care at all about dynamic range so long as the final medium is always going to be more limited than the medium used to capture the image in the first place?
--- End quote ---
Despite whatever limitations of the final medium, if there are discernible differences in the print that result from DR differences in the sensors, most of us would care.
The old, out of tune piano with some sticking keys will never deliver the whole tune, but 10 fingers will still do a better job than 5 ;-)
epsiloneri:
Dynamic range is the ratio between the brightest signal you can reliably detect, to the faintest signal you can reliably detect. This is close to your definition 1. Your definition 2 is closer to the numerical dynamic range, but is not necessarily related to the photographic dynamic range (because with DR = brightest/darkest the number of steps in between don't matter).
BTW, the human eye has a DR of about 30 stops (though not simultaneously). It's fortunate reproductions don't have that kind of DR, as it would easily be quite uncomfortable to watch. Just imagine actually being blinded by a photograph of the Sun...
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