There has been a lot of discussion on sharpness, diffraction and other pros and cons of DX vs FX.
However for the type of photography I do (and it seems most on Wetpixel) either format will work well with regards to sharpness if I make the right choices with lenses, domeports and f-stops.
For me, using digital, the limitations of digital until now have been the 'digital look' of images particularly in the specular highlight areas transitioning to highlights with detail, and of course noise in the underexposed shadows.
For me personally this issue takes precedence over sharpness, distraction issues etc.
Newer cameras appear to be much better in this regard (at the high end) and from the limited number of prints I have seen, the best prints I have seen are from a 39MP Hasselblad, followed by the new Canon 1DSMKIII (very close to Hasselblad), then the Nikon D3. (The Nikon wins in the low end noise end).
My question to the gurus who understand sensor technology is whether there are inherent benefits of larger sensors in these areas, particularly highlight areas?
In my quest to obtain higher and higher dynamic range images, in camera, is FX or DX likely to make a difference, or is it other design aspects of the sensor, camera firmware (EXSPEED, D-Lighting) etc that are more important?
Here I add an image I took this weekend at sunrise. I did manage to get an image that I like, but still with deficiencies and only with quite a lot of work in Photoshop. Of course underwater, sunballs are the main issue.

Great subject.
To me the dynamic range is the main drawback of my camera, the current one (D200) and the one before especially (D70), for long time I didn't upgrade the D70 since I didn't sow so much different in that area.

I think it's easier to say what doesn't contribute to improved dynamic range. Anything that happens after the capture can only degrade dynamic range (ignoring image combining of course) so things like EXPEED and D-Lighting aren't going to help. You have to have high resolution converters and low noise circuitry. Those are areas of active development.

Dynamic range is a per-pixel issue so it isn't sensor size that matters, it's the size of each pixel. A 12MP FX camera like the D3 or 5D has a clear advantage over a D300 while higher resolution full frame cameras may not. Not all sensors are created equal, though. If experts are to be believed, we should not expect dramatic advances in the performance of the pixels themselves as they are already quite advanced. Each generation has shown improvement though.

Dynamic range and ISO capability are frequently considered interchangeable but they aren't exactly the same. Nikon has made advances in their ISO capability through improved microlens arrays. That doesn't help with dynamic range but it does result in a base ISO of 200 (which can potential hurt us with sunballs!).

Having larger photosites is an enabler of greater dynamic range but it does not guarantee it. Other factors must also be in place. Medium format digital has had a reputation for better dynamic range for a long time. Those products have included higher resolution A-D converters but also it is claimed that the design of the bodies and lenses contribute. The pixel sizes themselves used to be larger but that is no longer the case with the highest resolution MF products today. I wouldn't be certain that a Hassy 39 or 50 has better dynamic range than a 1Ds3 but I don't know.

All digital works linearly which is distinctly different from how film works. It isn't so much that digital lacks dynamic range, it's that things that film handles gracefully can be very problematic for digital. I also think RAW converters aren't always as good as they should be. Anytime someone gains benefit from doing multiple RAW conversions of a single image and then combining them what they are really doing is working around shortcomings of the converter. I would not be surprised to see converters continue to advance.

Yes, this is the problem. We all got used to hilm which suffers from high intensity reciprocity law failure. Which in effect means that it produces a spurious result in sunbursts and other extreme highlights. We all got used to the effect and decided we liked it. Now we have digital systems which actually record more accurately and we don't like the result so much!

I use HDR (High Dynamic Range) techniques a fair bit on land - increasing dynamic range by using software such as Photomatix to produce 32bit and higher files from different exposures - but this can only really be used on static subjects with a tripod mounted camera for best results, and even so any movement results in ghosting and there are other strange effects. Sometimes it can be a very effective tool but for obvious reasons its problematic underwater!

Although its probably a contraversial comment, I'd say that cameras like the original Canon 1DS, and Nikon's D3 and D700 probably represent a good compromise between Mpixels and sensor size. I personally would have preferred to see Canon upgrade the sensor in the 1DS without boosting MPixels but unfortunately the world is fixated on MPixels! Now if Nikon will only build an ultrafast 20 or 24.......

I have been wading through some of the tedious testing methods for digital sensor testing like MFT and LW/PH etc, but have not found anything that pertains to dynamic range. If, a major component of dynamic range capabilities of a sensor is pixel size, is it likely that a camera like the 5D, D3, D700 may have better dynamic range than say a DS1MkIII or a future 24MP D3x. (Given similar A/D conversion technology).
If I were choosing a camera and lets say I was clear that my resolution needs were taken care of with a 12MP camera, should I consider that a higher MP camera may actually be detrimental to me if dynamic range was my priority?
Are there any objective measures of dynamic range to compare cameras?

Aren't Dynamic Range and Tonal Range two different things?

Craig pretty much nailed it. Pixel size matters, but only if all other things are equal, which they never are.

We keep talking about dynamic range and how different digital is from film. Again Craig stated why there is a difference, but we seem to forget that the dynamic range of the film depends on which film we are talking about. Sometimes people gripe about the lack of dynamic range of their digital camera compared to say, hmmm.....Velvia. Gee, I don't exactly remember a 12 stop range with Velvia.

The key is that the same range appears to be different. It's similar to the difference between noise and grain. I would tolerate more grain than noise. Noise just looks worse to me than grain. Luminance noise makes me gag.



I don't believe there a standard protocol for measuring dynamic range. I don't think it would necessarily help. I think there is more to it than that.



Great question. I would guess the answer would be - possibly or depends. I may have to defer to the Magic Eight Ball for this one though.

I too use HDR quite often on land, with some good results. I've only attempted underwater HDR once. The problem with using it underwater is that it is hand held (I suppose you could use a tripod, but I just can't be bothered) and shooting in quick sequence means that strobes can't be used (recycle time too slow as frame rate is about 9 frames a second). Here is the result.

I think Clark has a lot of interesting and very technical information on the subject: http://www.clarkvision.com/imagedetail/index.html

There is an objective engineering standard for dynamic range but it doesn't correspond to how photographers work. Photographers are familiar with zones where each zone is differentiated by a stop but the darkest zone must have a range of tones in it. How much range is subject to interpretation and that's why there is disagreement on how much "dynamic range" a digital camera offers. Is 12 stops of dynamic range equivalent to 6 zones, 8 zones, 10 zones? It depends. There's a big "language barrier" here.


As George said, it depends. A large pixel site like a 5D or D3/D700 has may be capable of more dynamic range than the rest of the processing chain can handle. In that case, the only real advantage they deliver is full dynamic range from base ISO to higher ISOs up to a point. The dynamic range of the system depends on pixel sites plus all analog stages up to the digital conversion. It also depends on how much contrast the optical section is capable of delivering to the sensor.

I would say, though, that it's conceivable that if/when Nikon delivers a 24MP body that the D3/D700 may be a better camera for sunballs. We will have to see.

I read recently on dpreview where Thom Hogan felt that a 20% increase in linear resolution is the minimum meaningful step that can be seen in the result. Given that arbitrary but reasonable definition, a 24MP camera will be two increments improved over a D3 (and the 1Ds, 1Ds2, and 1Ds3 are each separated by an increment). Paul argues that the 1Ds offers satisfactory resolution for him and that is where Nikon is with their three top DSLRs today. Would two increments of resolution improvement be worth degraded high contrast performance underwater? I think that may depend on what we shoot.

I think this is an interesting image Warren; how 'real' is this image? Is the speckled highlight in the foreground real or artifact of the HDR process? There does appear to be some noise in the shadows and background which is a common problem in HDR images.
Interestingly, I think HDR images could probably still work underwater even with strobe - if the strobe fired once providing the foreground exposure and then the bracketed shots provided the HDR for the background without the strobe.

What you are seeing in the foreground is not artifacting. The speckling is as a result of the zebra mussel infestation in the great lakes. The floor of the lakes are littered with zebra mussels and in some areas, there are white speckles from the reminants of zebra mussel shells when they are eaten by the gobies (another invasive species). There is a bit of noise in the shadows as I had to bump up the ISO (I can't remember how far, but probably in the 3200 range I suspect).

I may give the strobe suggestion a try at some point, next time I am out.

All you need to do is get a Fuji S5 (I got a new one last week for 475€ as a bargain backup for the D200) and get 11 EV steps. To give you a painful comparation, Canon 5D has 8.5, Canon 40D, Sony A700 and Nikon D3 have 9 (maybe 9.5 at the most for nikon D3 but stretching it a lot) ....

Unfortunately the tests shown here on WP a while back, do not seem to show any benefit of the S5 over D200 at least underwater with sunballs, so whether these specs really translated to any practical advantage is unclear.
http://wetpixel.com/i.php/full/from-the-fo...sunburst-tests/

I remember those tests and I just went again through them again and there is a factor that should be taken into account and is the lack of use of Fuji´s software (it did not exist at that time) that now allows to treat the 6 "bright" mpx and the 6 "shadow" mpx (PS did not make any distinction) which is like taking a HDR image with one shot.

From (in spanish):

http://www.guillermoluijk.com/article/superccd/index.htm

This the image taken by the type S (bright) mpx:


This is the one taken by the type R (shadow):


And this is the picture obtained when processing the image:



In the end, I do not know if it will be useful underwater but, I will give it a try as soon as I am able to get my camera (it was delivered to my parents house in Santander, in the north coast of Spain and I don´t know when I´ll go there). Anyway, for 475€, brand new, is a good camera (the shop sold 20 in one morning).

Is this of any help in your comparisons?

http://www.diwa-labs.com/wip4/test_result.epl

Thanks, this and Craig's references were very helpful. These tests would seem to confirm that when comparing cameras like the D3, 5D and 1DSMkIII, there would appear to be no advantage of the 1DSMK111 unless high resolution was a priority and that for equivalent low end ISO settings the D3 and 5D performance is at least as good as the 1DSMkIII in dynamic range and noise, color fidelity etc and then actually outperform the MkIII once one gets to 1600 ISO and beyond.
So for my maximum usual print size of 17x24 I probably would see little advantage to a FF camera beyond 12 MP or so with present sensor technologies.
I think a great point Clark makes in Craig's reference, is that unless we can change the laws of physics, bigger pixels will mean less noise and better dynamic range (everything else being equal), irrespective of changes in sensor technology.

Yesterday I used the fuji underwater for the first time and I have to say that sunbursts are very good, better than with the D300 if you ask me (and it was my first day with the camera). Straight from the raw (converted to tiff with HU-3 without touching anything):



I am just starting to use it but I really like the colours it delivers (reds and blues).

Bigger pixels are always going to win in the DR and noise comparisons. But it's a trade-off. Sometimes you need the extra pixels (safari, whales, etc) and sometimes you need the image quality. That's why I have a 5D and a 1DsIII

Cheers
James

Thanks for that; so this is the Fuji S5 correct? I have a new training regimen for you; now not only do you have to swim laps with the cameras, but you have to dive take a picture with the S5, surface, replace the s5 with d300, dive, take identical picture with d300, then repeat until you have completed macro, WA and sunballs etc.
This is a guaranteed world champion program, and we get to see the comparisons.

I can dive both at the same time so I don´t have to surface but, would that be cheating?


A couple more shots of the fuji:

the latest leaf camera back has 12 stops. in a recent test i read, can find it now though, the reviewer demonstrated that the d3 had 10 stops when shot in raw, 7-8 in jpg.

I believe two things are important in answering those questions. First, all sensors work the same way. It's possible to imagine a sensor that is inherently nonlinear but we haven't seen one yet. Fuji's design is interesting but it's still a linear sensor; there's just two of them at the same time. Second, there's a technical limit to how much dynamic range modern DSLRs can deliver and it seems to be around 12 stops. Many of us thought that the transition to 14 bits would fix that but so far that hasn't been the case. It's possible that 12 stops can be exceeded but we're not seeing it in 35mm DSLRs because of other constraints, most likely minimum speed requirements. Regardless of the technical reasons, it appears that there's a ceiling on DNR so the goal becomes making sure we bump into it.

With those two technical limitations on the current state of the art, we can say that we need a photosite large enough to hit the performance ceiling at the ISO speed we need and still give us the exposure options to capture sunballs correctly. FX versus DX becomes a resolution argument at that point. Until manufacturers overcome the 12 stop limit, larger photosites and bigger sensors aren't going to help. I would happily accept a 1 fps limit on a hi-res body to get more DNR. That's what MF cameras do.

Finally, Eric's sunball RAW conversions demonstrate that raw converters have an effect on the quality of output we get from those types of shots. Ideally, we should overexpose nothing and capture the full range of the scene but that's nowhere near realistic. Until the time when we can, raw converters make a difference.

It's an interesting thread but I'm a bit confused. The common agreement seems to be that size matters and bigger pixels result in better dynamic range.
However, I've just checked the new review of a900 on dpreview and this camera seems to have a better DR than the a700 that have less pixels (and obviously having bigger photosites):
http://www.dpreview.com/reviews/sonydslra900/page24.asp

What's your opinion?

And/or a lens argument

The a700 has a cropped sensor, whereas the a900 is full frame, so in fact the pixels on the a700 are not necessarily larger or as much larger as you would expect. I'm not sure what the actual pixel sizes are on each camera, and can't find a reference to this in Sony's literature.
Obviously there may be other factors such as advances in manufacturing processes from the a700 to a900 that can affect pixel size for a given pixel number and sensor area, such as decreasing the space between pixels allowing more space on the sensor for either more or larger pixels - this is what Canon has apparently done with their new sensors as promoted for the 50D and there are other factors that can be improved like the A/D technology which is a feature of the new a900 sensor.
The basic rule still applies though when comparing sensors that are identical in every other aspect besides pixel size.

The pixels on an A700 are smaller than an A900.

Dpreview does most of its dynamic range testing using JPGs and that doesn't tell you much about a camera's theoretical capabilities. Regarding their A900 raw test, their result of 12.6 stops is theoretically impossible to achieve with a 12 bit camera. You would think that such a result would tip the reviewers off that something is wrong with their testing methodology. Don't trust dpreview's dynamic range testing.

Sorry for my mistyping. I meant nikon d700 and not the a700. I hope my previous post makes sense in this way.

You suggested not to trust diwa-labs either.

Looking at the graphs they display for DR, it is hard to exactly draw the same conclusions that they do. The D700 also has the identical sensor to the D3 yet they show it to have less DR on their step wedge interpretation. I think the points made by Craig probably account for all of this and JPEG comparison of DR is probably invalid.

Yes I did. For good reason, too. My comments there were valid. They are here, too.

Just because someone puts up data and pretty pictures doesn't mean they are right particularly in the internet age. In diwa labs's case, and in dpreview's in this instance, it's clear they have methodology problems. The first thing they teach incoming freshmen in Engineering 101 is how to do basic sanity checks. Both of these testers have failed at that.

The fact is that 12 bit sensors cannot deliver 12.6 stops of dynamic range. I realize it. The dpreview tester apparently does not. Choose to believe who you want.

Spot on Craig. Unfortunately the internet is as good a place to spread misinformation as solid fact.

Having just been dealing with a large number of image files from differing cameras and different photographers but of similar subject matter, I can quite happily state that I can see differences (IMHO) in many aspects of the images. Whether these differences could be narrowed by adjustment of settings and careful post processing is another matter but to me there ARE differences and this to me is the reality of using different systems. Theoretical DR is one thing but actual may well be quite another.

Neither dpreview nor diwa. My only and last hope is Ken Rockwell :-)
Joke aside, I'm critical with these reviews but also with other statments written here. In the internet age you can find anything to prove that you are right. In this test, the nikon d700 is slightly better than the a900:
http://www.imaging-resource.com/PRODS/AA900/AA900IMATEST.HTM

Can I trust this? But it`s still not a huge difference. There are also lots of discussion on the forum of dpreview on this topic.

Why do you think, that 12 bit sensors has a 12 stop DR ceiling? Can you explain me!

I didn't see anything wrong with the Imaging Resource review. He doesn't know that 1/3 stop step charts don't produce 4 significant digits though. Once you realize that, seeing 12.1 stops out of a 12 bit camera isn't concerning, it's just an error of precision (and artifacts of software). The reviewer also expressed disbelief that the S3 could rate lower than other cameras. That suggests that he hasn't completely thought through what he is testing.

These days a "fact" can be established simply by stating it and having it recognized by someone else. We've even seen such tactics used as justification for a nation to go to war. I'm not equating the two, but it's very easy to publish something pretty, get a bunch of parasitic click-thru bloggers to link to it, then the next thing you know it's presented as fact on a Wikipedia page. I see wrong stuff posted on the internet every day now as bloggers don't feel any obligation to pass a sniff test. History is written and rewritten with unprecedented ease these days. Information is easy now so the burden is on us to be sharp.

I'll attempt to describe the 12 bit, 12 stop relationship:

Every stop represents a doubling or halving a light intensity. In the binary number system each digit (bit) represents a doubling or halving of the value of the digit next to it. The sequence 1,2,4,8 represents a doubling of the previous number and in binary that sequence is represented as 1,10,100,1000. As you can see, there's a direct correlation between photographic stops and bits in a digital value.

Let's assume that a digital camera has a 4 bit converter and that exposure is set perfectly to fully saturate highlights. In that case, a highlight pixel will have a value of 1111. Now let's stop down the exposure by one full stop. The resulting digital value will be half, or 0111. Doing it again results in 0011, a 3rd time results in 0001 and a 4th results in a totally black pixel. As you can see, the dynamic range of the camera is 4 stops and that's directly a result of the 4 bit converter. No linear digital system can have dynamic range greater than the number of bits in it's converter. It can have less.

In reality, digital cameras aren't quite perfect so a 12 bit system will have a bit less than 12 stops. If you read Clark he states that 11.6-11.8 is the realistic limit for 12 bits (figure 4 of that article). You would think that 14 bits would up the limit by two stops, and it does, but today's 14 bit converters don't have good enough noise performance at the speeds they run to realize the full gain in dynamic range.

There is also a difference in engineering dynamic range and photographic dynamic range and that confuses matters greatly. Since there is no standard for photographic dynamic range it's hard to compare in those terms, but photographic dynamic range is generally DNR - 3-5 stops. Photographers like to see shading in the lowest stop but they can't agree on how much.

BTW, I have great respect for the work required to perform meaningful testing of today's camera equipment and I believe that sites like dpreview do good work. It's still necessary to understand what they are testing, how to interpret it, and occasionally identify errors. Usually when you see something huge, like the diwa labs result, what is interesting is why the abnormal result occurred, not what the result suggests.

Doh, I think I've got it.



Craig,

Thanks for the very lucid explanation.

Craig,

Many thanks for the explanation!

Marcell

I was under the impression that the bit depth did not actually correlate with the breadth of the dynamic range, but rather the number of gradations within the dynamic range.
In other words one could still have a very broad dynamic range with any given bit depth - i.e. deep black to pure white, the difference with higher bit depth would be the finer density of steps in between and thus yield a smoother ramp from black to white.

Yes, that's a popular claim but it's not true. The number of "gradations" is, itself, dynamic range. If you start with a saturated sensor, then keep halving the exposure until you end up with either pure black or pure noise, you will have measured the dynamic range and adding bits to that will either increase range or increase noise, it will not increase "gradations" because there is no way add bits to a fixed amount of dynamic range. One bit equals one stop forever with linear sensors. Remember, a stop is a doubling/halving of light and a bit is a doubling/halving of value. That correlation cannot be changed; it's a mathematical truth not an engineering design decision. There is no possible flexibility in how that works.

In photographic terms there is a concept of zones. There are a number of zones separated by a single stop but the darkest zone has gradations. If we add bits we are adding gradations to the darkest zone but not necessarily adding zones (since the number of zones is an arbitrary choice) so in that sense you can add bits to improve gradations. The problem with that is there's a variable amount of dynamic range in the darkest zone, it's simply a failure to adequately define dynamic range quantitatively. Zones are related to dynamic range but they aren't the same.

Keep in mind that all this relates to the scene captured by the lens and recorded by the camera, the so-called "scene referred data". It not about the output TIFF or JPG which is (usually) not linearly encoded and is tone mapped. These files are known as "output referred data" and can have any amount of scene-referred dynamic range in them regardless of how the data is encoded. That's another common source of confusion. Let's say you have a JPG that's half white and half black. How much dynamic range does it have? The answer is that the question makes no sense.

I am little bit confused. If you have 4 bits, than you have

0000 = 0 pure black
0001 = 1 |
0010 = 2 |
0100 = 4 |
1000 = 8 v
1111 = 15 pure white

Isn't that almost 5 stops from pure black to pure white?

regards
rachid

OK; now I'm confused again. To use the photon in a bucket analogy again. Let's say a large D3 pixel (bucket) vs a smaller Olympus pixel. Take a photograph of a very high contrast scene at a set exposure. Some of the pixels will be full, some in the middle and some almost empty.
The larger pixel will collect more photons from the deep shadows before noise is evident than the smaller pixel, and the larger pixel will be able to collect more photons from the very bright highlights before it overflows and blows so to speak. This will be the case irrespective of bit depth at the moment of exposure. The difference that bit depth will make is the increments within the bucket that can be differentiated. It would seem to me therefore that bit depth is more important to facilitating the larger pixels recording more gradations or shades of grey (each representing a zone or EV value or stop), than it is to the extremes of dynamic range that it can record. In other words a large pixel sensor with low bit processing would still be able to record deep shadows with low noise, and extreme highlights without blowing, but might exhibit more contrast and or banding let's just say with a 4-bit processor vs a 14-bit. And of course the speed of processing / frame rate is improved with higher bit depth.
Or, to continue with this analogy will the 4-bit processor simply position itself toward the mid greys (partially filled pixels) recorded by the sensor and simply ignore the very bright and very dark areas' and then as you add bits more and more shades of grey at either end are added.

To answer that, does the 1 bit case have 1 stop of range or almost 2?

The photographer chooses the "position" of the bits when he chooses exposure so a 4 bit converter can't position itself in the middle, it will always be placed at the "top". Doing otherwise would be kind of like using mismatched ISO processing.

If you assume a 4 bit converter with today's modern DSLR photosites, there would be 6-11 stops of wasted dynamic range that the converter couldn't take advantage of. That would mean that you could increase ISO at least 6 stops from base without increasing noise. We see an example of that in the first generation 5D. Its photosites were capable of well in excess of the 12 bits its converter offered so you could bump the ISO several stops without penalty.

OK; clear. So one final clarification then. A 4 bit convertor would be able to record the increased high end DR of a high end sensor, or possibly the low end if so exposed, but not both.

1 Stop is 1 stop. sure...
But what is 1.9?

Yes.

This is tricky.

The total dynamic range of light is 2^n where n is what we call "stops". The total dynamic range of an integer is 2^m where m is the number of bits in the word. As you can see, the number of bits is directly analogous to the number of stops in an ideal linear system. It can't be any other way. Of course, that doesn't help with the confusion but hopefully it tells you what the answer is when intuition is telling you otherwise. It also doesn't help when there is fractional stops since you can't have fractional bits. It does tell you how many bits are needed for a given sensor capability though.

I'll attempt to describe this another way. I'm not a teacher and my engineering classes are 25+ years old at this point.

Any given intensity of light can be approximated by a sum of light sources of fixed intensities that are properly chosen. Let's say we have 3 different light sources where the first light source, A, is the brightest, the second, B, is precisely half as bright as the first, and the third, C, is half as bright as the second. In this case, we can describe any light source that isn't too bright using one of 8 values:

A B C : 0=off 1=on
=============
0 0 0 - darkest
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1 - brightest

There may be considerable error in our crude representation of light because we have only 3 measurements. That error is called quantization error.

A 3 bit linear A-D converter will generate a value that directly corresponds to the control word that determines which lights are turned on and off above. The reason for that is the converter outputs binary and we carefully chose our light sources to work in powers of two. As I've said before, a 3 bit converter will have 3 stops of range so that's what this system has, yet there is only 2 stops difference between the 3 reference light sources. The reason for that is that we can turn all the lights off or all of them on. That's what you are observing, rachid. All those "extra bits" are producing almost an extra stop; those combined with all zeros yield the last stop that means that 12 bits is 12 stops rather than just 11.

I hope that explanation helps. I've considered these things as one in the same for so long because of my background that I struggle to even explain it.

Hi Craig,
it helped! i understand you and now i have to think about.
I should drink one espresso more. That helps

rachid