ruthenium
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 Re: Utility of dynamic range beyond a certain point | |
snapsy wrote:
ruthenium wrote:
chiron wrote:
sbay wrote:
chiron wrote:
Yet, obviously, many paintings are spectacularly beautiful without doing anything like HDR and with a more limited dynamic and contrast range. That might teach us something about how much dynamic range we actually need to make a beautiful photograph.
When you say dynamic range, are you talking about the dynamic range of the painting itself? or the scene that the painter captured?
A plein air painter will paint an outdoor scene and have to deal with the exact same dynamic range challenges that a photographer would have to handle. Except the painter relies on their eyes to "capture" the information in the scene and then translate it to the more limited dynamic range of the canvas. A photographer would have to rely on the sensor to do the same, and then during editing map it to the more limited dynamic range of the monitor, or paper.
For paper, people normally talk about contrast range. A matt paper might have a contrast ratio (darkest black to brightest white) of 100:1 and a glossy paper might have a ratio of 200:1. I guess that's roughly to 7 to 8 stops.
I suspect paintings have greater contrast ratio than prints because they can use a wider variety of pigments. Apparently there are specialty paints, like Vanta Black, that can absorb 99.965% of light. I think that works out to a 3000:1 contrast ratio (11.5 stops). But even using something like Vanta Black, they are still mapping the scene they see with their eyes (maybe 15stops?) into the much reduced range of the canvas and paint. So I guess you could say they are still doing "HDR" except manually.
I am definitely talking about the dynamic or tonal range of the painting itself. Here's what Claude 4.8 came up with, which is somewhat different from your figures and closer to my experience of viewing images (and I think closer to Dan's points). But I appreciate what you are saying and I know that I may be not understanding your points clearly.
From Claude 4.8:
I asked: "Do oil paintings have anything equivalent to dynamic range in photography?
--Claude answered:--
"Yes, though the equivalent is more constrained and works differently.
"The closest concept is tonal range or the value scale an oil painting can render. A photograph captured digitally might encode 10–14 stops of dynamic range, but any reflective print—oil paintings included—is bounded by the physics of pigment and surface. The brightest possible value is the reflectance of the lightest paint (titanium white, lead white) and the darkest is whatever the darkest pigment absorbs short of perfect blackness. In practice this gives a contrast ratio of roughly 30:1 to 50:1 for most paint surfaces—comparable to a matte photographic print, and dramatically less than what a backlit screen or the original scene offers. So oil paint has a "dynamic range," but it's a narrow one, and the painter's entire craft of value management is essentially the problem of compressing a high-range world into that limited band."
--End of Claude--
What is interesting about painting's more limited dynamic-tonal and contrast range is how painters use it to create beautiful light and images. For example, Vermeer's rendering of light is exceptionally beautiful, yet the dynamic range in his images is very limited.
I think this is clear now that what interests you (and I share this interest) is different from the dynamic range of a camera.
You are interested in how one can create a visual illusion while using pigments which reflectance "gives a contrast ratio of roughly 30:1 to 50:1 for most paint surfaces". I believe that the key to the understanding of this illusion is in the nature of human (and animal and bird) vision. Our eyes can only tell if one patch is lighter or darker than another. We are relatively indifferent (to a degree) to the exact amount of light reflected from each patch. Thus, as long as a reproduction (painting or photo) respects the tonal differences in a scene, this scene should create an illusion of being realistic, even when the tonal differences can be highly compressed.
The dynamic range of a camera is about the amount of light (photons) that can be captured, relative to the intrinsic camera noise. Although both the light and the noise are "two sides of the same coin", there is little we can do about the noise (except manipulating it digitally, or cooling the camera sensor). Thus, the principal way to improve the dynamic range is by developing sensors that can capture more light - that have a greater "full well capacity".
To answer the question on whether more dynamic range can be useful to a photographer, one should ask the direct question on whether this photographer should benefit from the ability to capture more light. Note that this is different from asking whether this photographer might be interested in deep shadow recovery.
In simplified terms, add a stop of DR, and your camera would double the number of photons it can capture. More DR means that one can capture more bright scenes without losing details in the highlights.
Is this always necessary? - obviously not, only when one has bright light in a scene.
Is this always feasible in practice? - no, for the simple reason that the increased exposure necessitates progressively lower ISO. The usual implementation of ISO in a camera is through the shutter speed or the aperture. A really low ISO may mean a really slow SS that is impractical if there is some movement that the photographer intends to capture.
It needs to be added that the subject of dynamic range of a camera sensor can be confused or conflated with the dynamic range (bit depth) of the analogue-to-digital converter in the camera. I think it is the later that is more important for shadow recovery than the former.
Hmm, in my last reply I shared a PTOP link I generated showing the a7rVI's PDR advantage is from its lower read noise. I also previously described how DR/PDR is a full-range measurement and that shadows vs highlights is only a metering/exposure construct, so not sure what to make of your latest reply.
I believe you presumed that that post was about the A7RVI, while the post didn't mention this particular camera at all (I think this was Dave's problem with the post as well).
Regarding the A7RVI, I am aware of what you refer to, as I noted in post #4 on p.2 of this thread: "the PDR 12.55 of the A7RVI... is larger than that for A7RV (11.69), yet this is not achieved by capturing more light with the A7RVI. To the best of my understanding, this better PDR of A7RVI is the result of applying selectively a lower gain toward the "shadow signal" from the sensor."
When dealing with the general (disconnected from the specifics of the A7RVI) question on whether a larger dynamic range is useful, my view is that it is useful, when it is achieved by increasing the ability of a camera to capture more light. Thus, the post that you refere to in "not sure what to make of your latest reply" was expressing my liking of the ability to capture more light with the extended dynamic range (such as that of the GFX100S II, for example).
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