Film versus DSLR dynamic range

Started Jul 24, 2007 | Discussions thread
Jay Turberville Forum Pro • Posts: 12,917
Re: And...

Probably because it is darned poor evidence.

...WHERE is yours?

I offered images of step wedges. But that's really beside the point. Whether or not I have offered any evidence has no bearing on the point that your flame image is not a good demonstration of any particular dynamic range capability.

Let me know if you accept.

I'll be happy to send you
raw files of step wedges and you can develope them and show us how
there are usable tones beyond 9 or so stops. Every time I go there,
the noise gets pretty intense.

...I DID NOT ask for Stouffer wedges (I already got them, , long time ago

I know you didn't. But it naturally follows from your claims that a proper workflow should easily bring 10 stops of DR out of these images. I'm just giving you a chance to prove your point. You, of course, are free to accept the opportunity or decline it.

We are working under Dave's "REAL WORLD" images principle, and I have
asked him to step-up to the plate and send me FILM IMAGES, so I can
scan them and process them, using my skills and tools, and post the
results, here.

The problem with "real world images" is that they have to be metered carefully beforehand if they are going to be used to prove a certain level of DR. That's the problem with your candle image. We have no idea what the brightness values were. So we don't know what dynamic range was captured. And I really don't care what you think "we" are working under. And I'm working under any reasonable approach that can demonstrate actual dynamic range. That can be a "real world" image or any number of reasonable test images or exposure sequences.

P.S.: Cut the B.S. and grab your cam, fire your candle, on a
low-light area, set the cam to ISO400 and shoot HANDHELD. Come back
here, and let's see your "genius" at work...

There's no B.S. to cut. Your evidence just isn't very good is all.

Why handheld? That has nothing to do with dynamic range. Why ISO 400? How is that relevant? The point isn't comparing your camera with mine or to some other camera. The point is whether or not Roger Clark's dynamic range numbers have practical application or not. If you can supply some reasonably good source of info that documents the range of light values that we'd expect from a candle, then I might shoot one since that might make the test releveant. But if we don't have some good information on the brightness levels of the subject, then I don't see how taking a picture of it makes a case for a certain amount of dynamic range. Realizing the problems with shooting something like a candle flame doesn't take genius. It's just obvious.

Anyway, the image below demonstrates my point. It is a pair of nice boring pictures of a Stouffers step wedge. For those who don't know, each step represents a 1/3 stop exposure difference. Two strips are shown. Each is from the same raw file. The bottom one is a a "normal" developement that shows slightly more than 8 stops worth of steps and hence slightly mroe than 8 stops of DR. The darker tones don't show much visible noise. This is the 8 stops or so of DR that I say is comfortably achieved by most DSLRs.

The wedge above that one has been processed to bring the values beyond 8 stops into a useful range. On this image, you can make out steps that go as far as the 11th stop. But there is a lot of noise present in these last two stops. So the range of 11 stops is there, but the question that each photographer has to answer for themself is how useful those last extra stops of DR are? For me, they aren't usually very useful. I'm pretty comfortable pushing into 9 stops, and maybe even 10 in an pinch. - depending on final enlargement size and subject matter. I have no hesitation saying that this camera (E-330) easily has 8 stops of DR. But even though I can measure more, those extra stops don't represent a lot of useful image detail.

Now a camera with a larger pixel pitch and and hence typically greater well capacity will go into the the last three stops of DR more comfortably. But that isn't true of the vast majority of DSLRS. And further, Roger Clark says that even a 7Mp 1/1.8" sensor has 11 stops of DR. And while that that may be true technically, it isn't a good practical preditor of what you can expect when you take pictures. The usable DR is a few stops less. And the typical 6-10Mp sensor on an APS-C or 4/3" camera has a similar problem, just to a lesser degree.

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