GH3 = Mega PDR test (all ISOs, new results, D800 lost its crown, The Holy Grail is found............

Started 5 months ago | Discussion thread
Detail Man
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Re: GH3 = Mega PDR test (all ISOs, new results, D800 lost its crown, The Holy Grail is found ...
In reply to Great Bustard, 5 months ago

Great Bustard wrote:

... As we all know, Equivalent photos have the same DOF and shutter speed, which also results in the same total amount of light falling on the sensor. However, the parameter of "same shutter speed" is only relevant in low light.

But, let's consider Equivalent photos (same DOF and shutter speed) nonetheless. The DR is the number of stops from the noise floor to the saturation limit. The saturation will be the same for both since the same total light will fall on the sensor for Equivalent photos, unless we are at base ISO where the larger sensor can use a lower shutter speed than the smaller sensor.

That leaves us with the noise floor. The photon noise will be the same since the total amount of light falling on the sensors is the same for Equivalent photos. Thus, the difference comes down to read noise. However, one of two things will happen as the ISO increases: either the read noise will remain the same (ISOless sensor) or the read noise will lessen (non-ISOless sensors).

So, in no case does Equivalence have any bearing on DR, except inasmuch as it denies the larger sensor camera the opportunity to take advantage of a longer shutter speed, which would put more total light on the sensor resulting in less photon noise (irrelevant for DR, however) but does deny the larger sensor the advantage of its greater saturation capacity for base ISO shooting.

GB, Bill Claff seeems to imply that his PDR specification is normalized in some manner for the camera image-sensor's "circle of confusion". I am not able to find much in the way of further information on his web-site (though I may have missed it, if such is there, I have yet to find it).

His statement (below) seems to imply to me that the data is (presumably, perhaps) normalized based on some standard Full Frame COC diameter then scaled by the image-sensor's specific crop-factor.

That would make more sense that some kind of COC diameter derived from the dimensions of a 2x2 array of photo-sites (which would be a per-pixel-level scaling for per-sensor-level results).

"My definition of Photographic Dynamic Range is a low endpoint with an SNR of 20 when adjusted for the appropriate Circle Of Confusion (COC) for the sensor."

http://home.comcast.net/~NikonD70/GeneralTopics/Sensors_&_Raw/Sensor_Analysis_Primer/Engineering_and_Photographic_Dynamic_Range.htm

Have you any particular thoughts or any speculations as to what may be going on here (and why) ?

Edited 5 months ago by Detail Man
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