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Author Topic: The Optimum Digital Exposure  (Read 64457 times)

Guillermo Luijk

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Re: Re: Re: Re: Re: Re: Re: Re: Re: Re: Re:
« Reply #100 on: October 31, 2014, 07:47:17 am »

I may have misinterpreted your " Imagine you have one empty stop for a certain situation;" premise.

I think you did. That premise is the key in the situation described: usage of ISO to ETTR when aperture/shutter don't suffice.

bjanes

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Re: Re: Re: The Optimum Digital Exposure
« Reply #101 on: October 31, 2014, 08:02:47 am »

You confuse 'more data' with 'more information' which is the important thing in practice. The advantage of ETTR is not having more data but having more information through SNR improvement. A good example of more data but no more information (no SNR improvement) is pushing ISO on an underexposed shot on a Sony sensor. Or in nearly any sensor beyond ISO1600, because you get more RAW levels but the same SNR so there is no practical advantage.

Emil explains this fantastically in the article that produced your headache. A simple test to illustrate:



Image on the left has 4 times more data but the same information and robustness against postprocessing. The reason is noise dithering, the same process that takes place in RAW files.

Guillermo,

An excellent demonstration of how noise dithering can mitigate posterization when a reduced number of levels is available. Even without noise, fewer levels are needed than generally recognized, and the number of needed levels is predicted by the Weber-Fechner law. A good explanation is given by Norman Koren.

The brightest f/stop of a 14 bit digital file contains half of the 16384 levels or 8192. However, only 70 levels are needed to prevent visible posterizaiton. Since 8192 levels are not needed for any practical purpose, some of them could be discarded and this is what Nikon does when recording visually loss less raw files, as Emil explains in his treatise.

Bill
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jjj

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Re: The Optimum Digital Exposure
« Reply #102 on: October 31, 2014, 08:05:29 am »

Indeed, when did excessive noise ever interfere with our ability to make significant tonal adjustments ...,  Oh wait, it does (which explains many of those noise ridden 'creative' images/masterpieces). Maybe that's why ACR has a masking option in its Detail/sharpening panel, hmm.
I used to use Kodak recording film [1000 ISO and not known for it's lack of grain] and then pushed it in Acuspeed, a developer good at increasing film speed [3200ISO in this case] but not without increasing film grain. The reason being was that to my mind the end result looked good, because of the grain or what would now be called noise.

Something I've noticed over the years that those who obsess over technical stuff and sneer at 'creative' work tend to produce images that are certainly correctly exposed as well as being nice and sharp, but that's about it regarding the content of the image. I don't know if you are typical of such folk or the first exception to the rule, because you have no links to your work.
Here's a photo for your viewing pleasure,. It's grainy/noisey, the subject isn't even sharp and yet lots people seem to like it.



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jjj

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Re: The Optimum Digital Exposure
« Reply #103 on: October 31, 2014, 08:11:36 am »

You should know by now, Jeremy, that all appearances such as 'good-looking', 'ugly', 'beautiful', and so on, exist only in the mind of the beholder.

Technically better is unequivocally technically better, provided the science is sound.
But as the end result is usually  to produce images for people's viewing pleasure and not to simply duplicate reality, technically better may be irrelevant, which was my point. The whole reason why say film images looked good was because they were an interpretation of reality. The medium's limitations is what usually made photos look good.
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Ray

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Re: The Optimum Digital Exposure
« Reply #104 on: October 31, 2014, 08:52:39 am »

It's grainy/noisey, the subject isn't even sharp and yet lots people seem to like it.





The moment has been captured so well that lots of people like it despite the fact it's grainy, noisy and lacking sharpness.  ;)
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Ray

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Re: Re: Re: Re: Re: Re: Re:
« Reply #105 on: October 31, 2014, 08:58:31 am »

Ray,

I think that is not quite correct regarding the histogram to the right. Let's assume that you are shooting with a so called ISOless camera like the D800 in dim light. You would select an aperture small enough for adequate depth of field and a high enough shutter speed to freeze action. Once you have selected the exposure as determined by f/stop and shutter speed, you could take the shot at base ISO. In this case, the histogram will be far to the left. You then increase "exposure" in the raw converter. Its called exposure in ACR or LR, but it is really increasing the gain. Or you could increase the ISO on the camera to move the histogram to the right and take the shot with the same shutter speed and f/stop. The final result would be the same, except that with the higher ISO you have less highlight headroom.

Bill

Hi Bill,
To have a truly ISO-less camera with a wide dynamic range, would be a tremendous feature. However, the D800 and D800E are not really ISO-less, as you mentioned to me over a year ago.

If one underexposes by 6 stops at ISO 100, with the D800E, the DR will be reduced by 6 stops (or 6 EV), which would be equivalent to an ISO 6400 shot with an ISO-less camera, after exposure compensation in ACR.

However, according to DXOMark, if one uses the ISO 6400 setting with the D800E, and the same exposure as a 6 stop underexposure at ISO 100, the exposure will be an ETTR and the DR will be only 5.1 EV lower, instead of 6 EV lower. One gains a significant benefit of 0.9 EV in dynamic range by choosing to use an ETTR exposure at ISO 6400 instead of underexposing 6 stops at ISO 100.

This advantage is not as great as it would be with Canon DSLRs, but is still an advantage.
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Bart_van_der_Wolf

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Re: The Optimum Digital Exposure
« Reply #106 on: October 31, 2014, 09:11:26 am »

The reason being was that to my mind the end result looked good, because of the grain or what would now be called noise.

Which would be a nice thread topic by itself, Jeremy. Personally, I loath noise when there are better options available to drive the creative intent of an image home. When I look at the real world, I rarely see noise ... Adding noise, by choice of capture modality (if there is a choice to begin with, which I doubt in the case of HCB), can have it's use (e.g. by underlining the grungy feel of an image), but successful use is more exception than rule (more often it is a sign of sloppy technique, and a distraction).

Quote
Something I've noticed over the years that those who obsess over technical stuff and sneer at 'creative' work tend to produce images that are certainly correctly exposed as well as being nice and sharp, but that's about it regarding the content of the image.

That's funny, I just got of the phone with a fellow photographer who mentioned his astonishment about a recent museum exhibition he visited, showing (amongst others) both an original excellent platinum print of an image, and the same thing blown-up to cover a wall, but with purple streaky banding in the shadows, clearly poorly executed technique, no real excuse can be made, especially for a photography museum. Sloppy technique seems to spread, and is rarely used as an intentional creative element.

Quote
I don't know if you are typical of such folk or the first exception to the rule, because you have no links to your work.


Rest assured, I don't aspire to be like any other person. I hope I'm in some sense unique, or at least know my craft skills and my limitations, whatever they are. I also strive to improve my skills to avoid them becoming a distraction.

Quote
Here's a photo for your viewing pleasure,. It's grainy/noisey, the subject isn't even sharp and yet lots people seem to like it.

Are you suggesting it was an intentional creative choice of Henri to have it be noisy, or could the lack of available alternative materials be a part of it? If I'm not mistaken, Henri is also known to have sucked at printing his photo's which is why he let someone else do it for him. He knew his limitations, and didn't (ab)use them as a creative label. He knew he wanted to get the timing of events right. The image is sharp, but there was motion blur which was effective (recognition of the subject would also not have helped), although I do not know how intentional it was recorded by choosing a different shutterspeed.

There's a difference between a successful image despite of technical shortcomings, and one because of the shortcomings ...

Cheers,
Bart
« Last Edit: October 31, 2014, 09:14:03 am by BartvanderWolf »
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bjanes

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Re: Re: Re: Re: Re: Re: Re:
« Reply #107 on: October 31, 2014, 09:31:20 am »

However, according to DXOMark, if one uses the ISO 6400 setting with the D800E, and the same exposure as a 6 stop underexposure at ISO 100, the exposure will be an ETTR and the DR will be only 5.1 EV lower, instead of 6 EV lower. One gains a significant benefit of 0.9 EV in dynamic range by choosing to use an ETTR exposure at ISO 6400 instead of underexposing 6 stops at ISO 100.

This advantage is not as great as it would be with Canon DSLRs, but is still an advantage.

Ray,

Thanks for reminding me of that. The D800 is not truly ISO-less. I stand corrected.

Bill
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jjj

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Re: The Optimum Digital Exposure
« Reply #108 on: October 31, 2014, 01:08:48 pm »

Which would be a nice thread topic by itself, Jeremy. Personally, I loath noise when there are better options available to drive the creative intent of an image home. When I look at the real world, I rarely see noise ... Adding noise, by choice of capture modality (if there is a choice to begin with, which I doubt in the case of HCB), can have it's use (e.g. by underlining the grungy feel of an image), but successful use is more exception than rule (more often it is a sign of sloppy technique, and a distraction).
Nearly all photos are rubbish, usually through lack of any photographic skills and I'm not talking technical ability here, particularly as getting a sharp in focus image is so very easy nowadays. Successful imagery is the exception, full stop.
Personally I really like lo-fi imagery, but it is no easier to make look good than technically perfect shots. Possibly harder if anything.
I actually like grain or noise in images, to me it's in fact more real. Why? Because the world is full of texture, unlike than plastic smooth, digital images that have a video quality.
However banding in shadows or colour noise is something I cannot stand. LR/ACR remove colour noise really well leaving just the 'grain' which is fine by me. As for noise removal software, I've never seen any that actually removes noise and retains detail. Usually it simply looks like the image is softer/not sharp. BTW- adding grain to an image is something you can do to increase apparent sharpness/detail at times

Quote
Are you suggesting it was an intentional creative choice of Henri to have it be noisy, or could the lack of available alternative materials be a part of it? If I'm not mistaken, Henri is also known to have sucked at printing his photo's which is why he let someone else do it for him. He knew his limitations, and didn't (ab)use them as a creative label. He knew he wanted to get the timing of events right. The image is sharp, but there was motion blur which was effective (recognition of the subject would also not have helped), although I do not know how intentional it was recorded by choosing a different shutterspeed.
No I'm saying that noise doesn't necessarily matter. What does matter is the content of the photo.

Quote
There's a difference between a successful image despite of technical shortcomings, and one because of the shortcomings ...
As there is between a technically competent image and one that is actually interesting.  :P
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Fine_Art

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Re: The Optimum Digital Exposure
« Reply #109 on: October 31, 2014, 01:12:09 pm »

The moment has been captured so well that lots of people like it despite the fact it's grainy, noisy and lacking sharpness.  ;)

Nailed it.
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NancyP

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Re: The Optimum Digital Exposure
« Reply #110 on: October 31, 2014, 03:19:53 pm »

Tiny point concerning the following exchange:
"There are times, however,  e.g. photographing wild life or 'grabbing the moment' when ETTR is difficult to employ."
This is the beauty the OneZone method #2. You set your exposure for EV +1-1/3 then bracket +/-2/3 of the stop!. If you put these settings in one of your camera presets, when the time comes for "grabbing the moment" you just simply hold your finger on the shutter button (capturing 3 exposures) then go on to the next scene.

I shoot action sequences of wildlife in which I have a second or two of capture time, and I put more priority on catching the most interesting posture, wing position, etc than on perfect ETTR. Basically, I put the camera on continuous high speed drive, hit the shutter when the action commences (bird in flight comes near, heron dives at fish), and capture 2 seconds of action. I wouldn't bracket.
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telyt

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Re: The Optimum Digital Exposure
« Reply #111 on: October 31, 2014, 03:27:10 pm »

Tiny point concerning the following exchange:
I shoot action sequences of wildlife in which I have a second or two of capture time, and I put more priority on catching the most interesting posture, wing position, etc than on perfect ETTR. Basically, I put the camera on continuous high speed drive, hit the shutter when the action commences (bird in flight comes near, heron dives at fish), and capture 2 seconds of action. I wouldn't bracket.

Agreed.  Bracketing increases the chances that the 'right' posture or activity will coincide with the wrong exposure.
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jjj

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Re: The Optimum Digital Exposure
« Reply #112 on: October 31, 2014, 03:32:07 pm »

The moment has been captured so well that lots of people like it despite the fact it's grainy, noisy and lacking sharpness.  ;)
My point entirely.
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jpegman

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Re: The Optimum Digital Exposure
« Reply #113 on: October 31, 2014, 03:36:39 pm »

Agreed.  Bracketing increases the chances that the 'right' posture or activity will coincide with the wrong exposure.

I agree 100% - No one said this is for 100% of your shooting, so if you worry about critical timing then this process is not for you. Fall back on whatever works for your shooting style-requirements.
However, if you want the best quality you can extract from your sensor and you have the time for at least 3 bracketed shots (<1sec on most DSLRS!), then this is one process to apply!
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jjj

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Re: The Optimum Digital Exposure
« Reply #114 on: October 31, 2014, 03:44:48 pm »

I shoot action sequences of wildlife in which I have a second or two of capture time, and I put more priority on catching the most interesting posture, wing position, etc than on perfect ETTR. Basically, I put the camera on continuous high speed drive, hit the shutter when the action commences (bird in flight comes near, heron dives at fish), and capture 2 seconds of action. I wouldn't bracket.
I'd use manual exposure for that sort of thing and set it to ETTR - if that was my preferred method.
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Bart_van_der_Wolf

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Re: The Optimum Digital Exposure
« Reply #115 on: October 31, 2014, 03:53:59 pm »

Quote
There's a difference between a successful image despite of technical shortcomings, and one because of the shortcomings ...

As there is between a technically competent image and one that is actually interesting.  :P

I prefer an image that is both. Are you suggesting they are exclusive qualities?

Cheers,
Bart
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jjj

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Re: The Optimum Digital Exposure
« Reply #116 on: October 31, 2014, 04:01:03 pm »

"As there is between a technically competent image and one that is actually interesting.  :P"

I prefer an image that is both. Are you suggesting they are exclusive qualities?
Not at all.
But I will say that those who obsess over tech stuff do tend to produce competent, but uninteresting photos
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Telecaster

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Re: The Optimum Digital Exposure
« Reply #117 on: October 31, 2014, 04:04:43 pm »

I actually like grain or noise in images, to me it's in fact more real. Why? Because the world is full of texture, unlike than plastic smooth, digital images that have a video quality.
However banding in shadows or colour noise is something I cannot stand. LR/ACR remove colour noise really well leaving just the 'grain' which is fine by me. As for noise removal software, I've never seen any that actually removes noise and retains detail. Usually it simply looks like the image is softer/not sharp. BTW- adding grain to an image is something you can do to increase apparent sharpness/detail at times

Yep, I agree with this. Chroma & patterned luma noise I don't like. Grain-like luma noise not only doesn't bother me, I often accentuate it for effect. Given that photography is for me a creative enterprise, whatever helps me get a look I like or find compelling or even provocative is the optimum thing to do. Attempts to impose any particular ├Žsthetic or approach as the "right" one should be disregarded.

-Dave-
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Bart_van_der_Wolf

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Re: The Optimum Digital Exposure
« Reply #118 on: October 31, 2014, 04:13:31 pm »

Not at all.
But I will say that those who obsess over tech stuff do tend to produce competent, but uninteresting photos

LOL, that's like suggesting that people like Rembrandt van Rijn, or Johannes Vermeer, or even Leonardo DaVinci, to just name a few commonly known ones didn't care (or even obsess) about the process as much as the composition and the politics of those times.

Cheers,
Bart
« Last Edit: October 31, 2014, 04:15:04 pm by BartvanderWolf »
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jjj

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Re: The Optimum Digital Exposure
« Reply #119 on: October 31, 2014, 08:05:44 pm »

LOL, that's like suggesting that people like Rembrandt van Rijn, or Johannes Vermeer, or even Leonardo DaVinci, to just name a few commonly known ones didn't care (or even obsess) about the process as much as the composition and the politics of those times.
No it isn't. People with talent who learn the technicalities of painting are very different from those who obsess of the technicalities of photography. The major difference between photography and painting is that no matter how much you know about technicalities, if you have no innate talent, you very obviously still cannot paint. With photography, if you know the technicalities [which are not exactly tricky] you can produce photos that are correctly exposed, in focus etc, even if you have no eye for composition or any creative ability at all.

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