phase versus hassleblad

[BernardLanguillier]

Hamamatsu, Nikon, etc... all agree on this definition

"The dynamic range value, however, corresponds to the limiting situation in which the full well capacity of a sensor element is reached, and is defined as follows:
Dynamic Range = Full Well Capacity (electrons) / Read Noise (electrons)"

A difference of 6 stops is.... hmmmm.... quite significant, and you don't have many factors to play with.

...Not to mention that, since the photosites of the D3x and the P65+, have the same size, there are also very few theoretical reason why the P65+ should have any advantage of DR.

One could mention CCD vs CMOS, but if anything the CMOS sensor is said to be less noisy, which has a great impact on DR from its very definition. The rest belongs to technology, and my bet if on Sony/Nikon vs Kodak or Dalsa. There is overall a very good correlation between R&D investments and the quality of the resulting technology...

So all things considered, it would in fact be surprising if the P65+ had better DR than that of, say, the D3x.

Regarding perceptions, the widespread impression that backs have more DR is the consequence of the system calibration in favour of under-exposure away from the ideal exposure to the right. The histogram of most backs shows values that are under-exposed relative to the actual values, which gives the false impression that highlights can be recovered better. It should be obvious for anybody familiar with DR measurements that shadow noise is the deciding factor in both theoretical and real world DR.



Cheers,
Bernard

[BernardLanguillier]

No, I did not perform any tests.  Since there was universal agreement, I took them at their word.

Mark,

Then, may I suggest that you remove asap these comments from an otherwise interesting piece to which they very clearly don't belong?

There are reasons why some people decide to shoot with a MFDB. In the end the only justification for the price of these backs is the fact that some photographers are willing to pay that much money. Some of these reasons are totally justified (look, lenses, system, resolution of a single capture), the reality of others is a lot less clear, starting with DR.

I don't see why you feel the need to damage your reputation to comment on this last point without theoretical analysis nor actual measured evidence.

As far as the comments from the people having seen your print, I would leave it to them to write their own piece on the topic. I really hope you realize that there is only a weak relationship between the look of a print and the DR of the device used to capture the initial image. Their comments only speak about you abilities as a printer.

Final comment from me on this.

Cheers,
Bernard

[BernardLanguillier]

Yes, indeed. You could post a reference to the DXO site or post your own data, but it would be a waste of time since it would be ignored be the elitists on this forum who substitute "expert consensus" for data and scientific analysis.

I don't know whether they are elitists or whether that is a problem in itself. Many of them are very good photographers, which is the most important thing. I would agree that they are elitists in the regard and consider this as a very good thing.

Now, some once justified urban myths live long. Many people still think that Canon camera have the best high ISO in the market, or that Ansel Adams images have the highest resolution of any landscape image ever shot,...

Another thing is that the MFDB is enough of a club that the influence of the vendors is strong. I don't expect Phaseone and Hassy to deliver objective information about their products relative to the competition but there is a natural trend to believe things that are repeated ad nauseum by overal good people you know.

Finally, backs have enough objective differentiators not to have to over sell DR... but the problem is that most photographers actually don't need the resolution,... and in the end the belief that DR is superior remains an important factor in the decision. Once purchased, the slight under-exposure of the backs calibration provides good apparent highlight recovery (close to negatives than to slides) and most photographers actually like that since it is safer for them, so this valiates their initial belief.

So all in all, the belief about the superiority of the back for DR is comfortable for both the vendors and the buyers. It is here to stay.  

Cheers,
Bernard

[Josh-H]

DXOmark lists Canon 1Ds MkIII you have tested to have quarter of a stop less dynamic range as Phase P65 Plus. While there are certainly different ways to measure and interpret the results, going from 1/4 to 6 EV difference in DR with any interpretation would be shocking.

I was going to make this point myself but in the end decided not to - simply because I actually don't have any direct experience with the P65+ (I do have extensive experience with the 1DSMK3). Therefore I leave it to others (such as Mark) who have used both cameras to confirm or deny accordingly.

Experience has shown me however that the 1DSMK3 has significantly better DR than film (and I used to shoot film) so I raise an eyebrow at the comment that film has better DR than a DSLR (because it doesn't in my experience).

As to the D3X - having compared files from my friend's D3X to my 1DSMK3 we both agree that the D3X has the edge in DR. That puts it somewhere well above film and somewhere between the 1DSMK3 and the P65+ in DR in my book (the reference to the P65+ being purely based on DXO (as noted above I have no experience with it).

All of this is pretty much academic arm chair pissing contest stuff really. What really counts is getting the shot with the tool you have at hand. And all of these tools will do a great job in the hands of a skilled operator so I personally see little point in getting to hot under the collar about an individuals opinion and expression of that opinion.

Overall I thought Marks article was informative, well written and interesting (even if I don't agree with everything he wrote)  - thank you Mark.

[Mark D Segal]

...Not to mention that, since the photosites of the D3x and the P65+, have the same size, there are also very few theoretical reason why the P65+ should have any advantage of DR.

.......................


Cheers,
Bernard

Bernard, I also have a professional deformation that tends to put faith in numbers - more than is often deserved actually - and in this case, I can tell you frankly the numbers don't tell the whole story. Phase-1 actually designs their own sensors. They've been in this business for many years and they have some of the brightest, mostg experienced people on the planet doing it. Dalsa manufactures the P40+ and P65+ under their supervision. There is much more to sensor design - both physically and firmware - than the pixel pitch would reveal. We had a very interesting seminar on that at the PODAS Death Valley workshop from Klaus Molgaard, their chief technologist. That was back in November amongst a lot of other stuff so I forget the details by now, but one always carries away certain basic messages from such sessions and I remember being impressed at the time that one needs to know a lot more about this than we can srumise from published specs.

I don't know whether you own an MF system, but I bought one mainly on the strength of the performance in deep shadow areas and the stunning resolution with the barest minimum of sharpening. As you undoubtedly know it takes patience to use it properly, but it returns more than I can expect from my Canon 1Ds Mk3. I went into an exploration of the MF environment very agnostic about whether the difference in IQ would be worth investing in, and in the final analysis I decided if I wanted the ultimate in image quality that a camera system could deliver, this is it - even for 13*19 inch prints. I took special care to evaluate my decision in that context, because I seldom print larger than that.

[feppe]

All of this is pretty much academic arm chair pissing contest stuff really. What really counts is getting the shot with the tool you have at hand. And all of these tools will do a great job in the hands of a skilled operator so I personally see little point in getting to hot under the collar about an individuals opinion and expression of that opinion.

And that's why I rarely comment on technical posts or articles as people usually argue about arcane minutiae with absolutely no impact on real-life IQ.

The resulting discussions too often end up looking like high-end audiophiles discussing the merits of soaking your SPDIF contacts in goat-urine for less warble. This is especially true with MFDBs with their "microcontrast" and "tonality" which nobody seems to be able to quantify, or even agree on their definition. These terms and other claims are often thrown around to prove MFDB superiority, accompanied with a jedi-handwave.

But this front-page article claims one can "see the difference [between dSLR and MFDB DR] from 30 feet away in a small print" based on anecdotal evidence, and slashes several stops of dynamic range from dSLRs based on statements from "experts." Oh, and calls AA filter a "blurring filter." It's one thing to write a non-technical article, and another to make brow-raising quantitative statements unsupported by any semblance of the scientific method.

[Mark D Segal]

Another thing is that the MFDB is enough of a club that the influence of the vendors is strong. I don't expect Phaseone and Hassy to deliver objective information about their products relative to the competition but there is a natural trend to believe things that are repeated ad nauseum by overal good people you know.

Finally, backs have enough objective differentiators not to have to over sell DR... but the problem is that most photographers actually don't need the resolution,...

Cheers,
Bernard

Bernard, please, let us set aside polemics and deal with facts. I don't know what club you're talking about or should I be paranoid because I'm not a member;   now, while the Phase-1 people are very decent folks to do business with, I'd be insulted if I believed you thought they can sell me a bill of goods which defies my own vision. And you know, sometimes, although I hate to hear myself say this, there can be truth in advertising. Why shouldn't they be expected to deliver objective information about their own products? They're selling into a niche of people who aren't easily deceived by propaganda. Your comment seems to be taking the vendors as fundamentally dishonest and their customers for idiots. I can't imagine you really believe this. Now, when you say that most photographers don't need the resolution - again quite a statement - I wouldn't hazard a guess about what most photogrpahers need because I don't wear their shoes or occupy their mindsets. But I hope I know my own head. Do I "need" all that resolution? Maybe yes, maybe no, it depends, and for when I think I do, it sure is "nice to have".

[Wayne Fox]

...Not to mention that, since the photosites of the D3x and the P65+, have the same size, there are also very few theoretical reason why the P65+ should have any advantage of DR.

Maybe not quite that simple, since the actual light sensitive area on each of the photo sites is quite a bit different. I believe only 10% of the surface of each CMOS site is light sensitive, whereas around 30% of each site on a CCD is light sensitive.

[deejjjaaaa]

Maybe not quite that simple, since the actual light sensitive area on each of the photo sites is quite a bit different. I believe only 10% of the surface of each CMOS site is light sensitive, whereas around 30% of each site on a CCD is light sensitive.

aren't they putting microlens (even in gapless design) on top of the surface to direct the light to those "actual light sensitive areas", are they ?

[Ray]

I went into an exploration of the MF environment very agnostic about whether the difference in IQ would be worth investing in, and in the final analysis I decided if I wanted the ultimate in image quality that a camera system could deliver, this is it - even for 13*19 inch prints. I took special care to evaluate my decision in that context, because I seldom print larger than that.

Mark, Mark, Mark,

You seldom print larger than 13"x19" yet you've invested in an MFDB system??? What are we to think?

Are you the ultimate pixel-peeper?  

Here's what Mark Dubovoy wrote about pixel peepers, to quote:

Beware Pixel Peepers! A typical P65+ file in TIFF format is 386 Megabytes. Hasselblad H3D II files are slightly over 300 Megabytes each. It is totally impractical to present multiple images of this size on line. Furthermore, to even begin to evaluate the color in one of these images requires a perfectly profiled and calibrated professional graphics grade display (no, your mighty 30-inch Apple or NEC or other “standard” computer displays are not even remotely up to the task). The images vastly exceed the color gamut of most monitors. Also, remember that a computer monitor is inherently a low resolution device. Even the best HD monitor has a resolution that pales in comparison to an inkjet printer. Add to that the fact that the images presented in the article are either screen shots or JPEGs in a much reduced color space (sRGB) and the conclusion is that if you try to “pixel peep” you are wasting your time and you are likely to reach meaningless conclusions.

Now to contrast this statement, I would like to describe my own experiences as regards pixel-peeping.

As one gets older, one tends to become more long-sighted. That is, reading requires spectacles, but the full moon on a clear night might still appear detailed.

So it was with me. About 16 years ago, reading became a bit of a strain, and the optician prescribed spectacles with a +1x magnification.

16 years later, those same spectacles required for ease of reading are now perfect for long distances, such as trees on the horizon or the moon on a clear night.

I don't need the spectacles to get around, drive a car etc. If I wasn't into Photography and wasn't concerned about resolution, I just wouldn't bother. But I know through experimentation, if I want to appreciate the maximum detail of a distant scene, I need spectacles with a +1x magnification.

If I want to pixel-peep two images on my monitor at 100%, or 200% or even 400%, I need spectacles with a +2.5 to +3x magnification.

If I want to see the maximum detail in a high quality HD source on my 65" plasma TV, I need spectacles of +1.25x magnification, and I need to sit no further than 2.4 metres (or 7ft 10in) from the screen.

I mention this just to demonstrate that I have no reason to believe that my eyesight is deficient when using the appropriate specatcles.

If one examines Mark Dubovoy's statement about pixel peeping more carefully, he seems to be implying that the print from the MFDB file is so significantly better than any crop at any enlargement viewed on the monitor, that pixel peeping is not relevant, partly because an inkjet printer has higher resolution than a monitor, and also because some printers have a slightly wider color gamut than even a good monitor.

I don't find these reasons at all credible in light of my own experiences. If the print is better than the view on the monitor (in terms of resolution at the appropriate magnification on the monitor), or in terms of color gamut which the monitor cannot display, then such differences are of a pixel-peeping magnitude.

Furthermore, Mark Segal, any 'additional' qualities you see in your 13"x19" print from an MFDB file (as opposed to a 35mm file), viewed from the distance you would read a book, will disappear from even a slightly greater distance, like 600mm, never mind 2.4 metres.

[Schewe]

No, I did not perform any tests.  Since there was universal agreement, I took them at their word.

Mark, Mark, Mark...

Surely you must realize by this time that NOTHING any English speaking representative of Nikon or Canon is in the least bit useful (nor factual). It's not that that wouldn't WANT to tell the truth...it's just that nobody from Canon nor Nikon USA would possibly know the truth.

You really, seriously need to step away from the "7 stop range" you are attributing to DSLR cameras and revise it upwards...

I haven't done the "technical tests" (as though that somehow means something to the aesthetics of an image) but I would guess that DSLRs are in the range of 9-10 stops at their natural ISO (not pushed to higher ISOs).

Depending on your definition of usable range, DSLRs might go over 10 stops...but I doubt anybody who has used a medium format back would doubt the range to be in the 12-14 stop range (depending on your definition of usable range vs noise).

Aside from the off the cuff comments at the end of the article, I'm glad you did it...interesting and useful!

Thanks...

[ErikKaffehr]

Hi,

Just a few remarks. To begin with, it is really the question of dynamic range. There is a technical definition and by that definition the leading DSLRs are in excess of 12 stops and so they are easily in the same range as MFDBs. I would also say that this has been thoroughly investigated by DxO mark. Having double the amount of pixels would add 0.5 stop if all other factors were kept constant. This is essentially quite consistent with the DxO-findings which peg the Phase One P65 plus at 11.5 stops on screen but 13 stops in print (normalized to 8 MPixels). The Nikon 3DX comes in at 14/13.

The second issue is the DR of film, I have mostly used Velvia and could see no detail 2 stops over nominal exposure and very little at 2 stops under nominal. I normally would expose Velvia at +1.5 stops for white snow, for instance.  No way I'd consider Velvia to have a dynamic range close to a DSLR! The discussion Mark had with the DSLR vendors may have stemmed from the vendors talking about JPEG. JPEG has by definition a dynamic range of 8 stops, but those 8 stops are in gamma compensated space. I don't know what this means in practice.

The last point is that prints really don't have a DR in much excess of 7 stops. That's absolutely true and can never be a discussion about. Why? Because max density on paper seems to be around 2.3 and minimum density around 0.1. So max density - min density is about 2.2. A stop is 0.3 density units so paper has a DR of about 7.3 stops. With some papers and BW 7.6 stops may be achievable.

Whenever we utilize DR in excess of 8 stops in print it can only be achieved careful mapping of brightness values to paper densities in order of getting the perception of great dynamic range.

Aside from my observations regarding DR the article was interesting to read. In my view the comparison photos were well designed for the intended purpose, namely to investigate the difference between single shot and multi shot.  

Another observation I may make is that using a white background with a small subject put large demands on the "anti flare" measures in the camera and lens.

Best regards
Erik Kaffehr

I can see that my remarks about Dynamic Range have sparked quite a bit of discussion.  Thank you all.  This is very healthy and quite interesting.  

So let me explain where I am coming from:  

About a year ago I was very curious about how the dynamic range of DSLR's compared to film. Part of my curiosity came because I had heard a few professional photographers complain that DSLR's could not approach film in this regard. I made a number of calls to Canon, Nikon, Kodak and Fuji.  There was a universal consensus among the technical experts at these companies that top DSLRs delivered roughly 7 F/stops of dynamic range while most transparency film (there are obviously variations) delivered about 8 F/stops of dynamic range.  The point was that they were relatively close. Negative film had somewhat higher dynamic range, according to Fuji about an extra F/stop.

It is important to note that during those discussions dynamic range meant how many F/stops you could capture and still deliver texture and detail.

No, I did not perform any tests.  Since there was universal agreement, I took them at their word.

Now, turning to Medium Format, the factory spec for PhaseOne backs is approximately 13 F/stops. I know from experience shooting with these backs that they do deliver this kind of dynamic range.

This is how I came up with the numbers.

My experience with a Canon 1DsMKIII and my P65+ back certainly bears out a huge difference in dynamic range capabilities. I have never done a side-by-side measurement, but there is definitely a very large difference; 6 F/stops would not surprise me at all.

The reason for my comment of 30 feet is  based on recent anecdotal evidence. About one week before I started writing the article, I went to the camera store and I had with me an 8x10 inch print from an image that I shot using an ALPA camera with the P65+ back.  A couple of photography enthusiasts entered the store, and from about 30 feet away I heard one of them say "WOW, look at the dynamic range in that picture".  Then, they approached me and kept asking how many shots it took, and how I did the HDR processing of the multiple shots, etc.  They were stunned that this came from a single image capture. They also commented that "you could never get that kind of dynamic range out of a single image with a small format DSLR".  There are two salient points here:  First: One of the striking things about high end Medium Format backs is their dynamic range capabilities.  Second: You can detect it from quite far away.  If you do not like 30 feet, then make it 10, or whatever makes you feel good.

I would never state as fact something based on a single instance of anecdotal evidence, but this short piece of anecdotal evidence is typical and constantly repeats itself.  I find that (if the original subject has it), the first thing that strikes the viewer about a Medium Format digital image is the dynamic range.  The second thing is the level of detail retrieval and natural looking sharpness.

Having said all that, I am always interested in new evidence and new data, and if there is proof that some newer small DSLR (I have never used or tested a D3x for example) can match the Medium Format backs in dynamic range, I will be the first one to be ecstatic that the technology is getting better, and I will also stand corrected.  If anyone has the right measurements and/or the proper visual experience, please be so kind as to share it.

To summarize: My visual experience to date, combined with what I have heard from the manufacturers themselves points to a very significant difference in Dynamic Range capabilities between Medium Format and smaller DSLR's.

I hope this is helpful, and again thanks to all of you for the discussion.

Mark Dubovoy

[ErikKaffehr]

Hi,

Mark talks about DR and not resolution. Anyone, except a blind man/woman, could see a difference between black and white at 30 feet.

That said, I don't understand some of Mark's statement regarding DR.

Best regards
Erik

Jeff, the article says 30 FEET, not inches.  Unless someone has superhuman vision, telling any difference between like prints from different cameras at this distance would be amazing.  I don't have any horse in this race other than this statement.  I found the comparison quite interesting to read given these cameras are way beyond both my interest and price range.  What I will do is my own experiment to compare a small print from my Canon S90 and Nikon D300 and see at what point I can tell the difference.  Will report back to all but I don't hold much faith that I can do this at 30 feet.

[bokehcambodia]

Interesting read,
the only things i cough up on are the DR misinformation and that a NEC wide-gamut SpectraView II screen is not good enough for judging, according to his opinion. Only EIZO does the job ?! Anyway, seems Hasselblad and Phase One need to rethink their plastic bodies...

[BernardLanguillier]

Bernard, I also have a professional deformation that tends to put faith in numbers - more than is often deserved actually - and in this case, I can tell you frankly the numbers don't tell the whole story. Phase-1 actually designs their own sensors. They've been in this business for many years and they have some of the brightest, mostg experienced people on the planet doing it. Dalsa manufactures the P40+ and P65+ under their supervision. There is much more to sensor design - both physically and firmware - than the pixel pitch would reveal. We had a very interesting seminar on that at the PODAS Death Valley workshop from Klaus Molgaard, their chief technologist. That was back in November amongst a lot of other stuff so I forget the details by now, but one always carries away certain basic messages from such sessions and I remember being impressed at the time that one needs to know a lot more about this than we can srumise from published specs.

Hum... Mark, have you have heard the equivalent speech done by Sony/Nikon engineers? I believe that they also describe themselves as being the best in the world at what they do. In the end these are just claims.

Figures do tell the whole story, especially when they are measured on an actual device just like DR can be. We are not talking about doggy predictions resulting from a potentially flawed theoretical model, we are talking about hard facts here.

Cheers,
Bernard

[BernardLanguillier]

Bernard, please, let us set aside polemics and deal with facts. I don't know what club you're talking about or should I be paranoid because I'm not a member;   now, while the Phase-1 people are very decent folks to do business with, I'd be insulted if I believed you thought they can sell me a bill of goods which defies my own vision. And you know, sometimes, although I hate to hear myself say this, there can be truth in advertising. Why shouldn't they be expected to deliver objective information about their own products? They're selling into a niche of people who aren't easily deceived by propaganda. Your comment seems to be taking the vendors as fundamentally dishonest and their customers for idiots. I can't imagine you really believe this. Now, when you say that most photographers don't need the resolution - again quite a statement - I wouldn't hazard a guess about what most photogrpahers need because I don't wear their shoes or occupy their mindsets. But I hope I know my own head. Do I "need" all that resolution? Maybe yes, maybe no, it depends, and for when I think I do, it sure is "nice to have".

Well, the value of a direct customer-vendor relationship in B2B business is proven enough to be a fact.

As far as vendors being liars and buyers idiots, these are your own words, I never wrote that nor implied that. There is a long list of possible behaviors between the most honest (and let's be clear stupid) one that would consist in emphasizing the weaknesses of one own's product vs the competition on the one end, and openly lying about both on the other hand.

Unless you have done a thorough measurement of the DR of your back vs that of high end DSLRs it would appear that you have believed the numbers proposed by the vendor of your back at least in absolute terms if not in relative terms compared to your previous camera. If not you may want to either present your test results, or phrase your position as an impression.

Regarding impressions, I am not sure about the 1ds3, but I know that my D3x gives me totally clean shadows at base ISO, with a potential for lifting so high that I have hardly done any HDR in 1.5 years. I don't feel any need whatsoever to do any HDR in outdoor conditions, however harsh the light. The only case where I still do it is in some interior/exterior cases where even the human eye had problems dealing with the contrast in one shot.

So there you go, we have similar impressions with different devices, I suggest we use numbers to make things more objective.

Cheers,
Bernard

[fredjeang]

 There we go. It was a topic about comparing 2 MFD cameras and we are now in the war between 35mm FF cmos and MFD ccd  lovers...
In that non-ending war, everybody becomes an engineer and scientist for a while. We will soon have graphics, mathematical equations and home made thesis. But very little real image comparaison.
And now the snobish factor in order to explain why there are still crazy photographers ready to spend a fortune in MFD while they all should better buy a D3x ?
Are we serious, really??

[ErikKaffehr]

Wayne,

I think you are right on the issue, although the percentages may be a bit higher according to my reading. CMOS sensors normally have microlenses, which compensate for part of the difference between CMOS and CCD. Sony works on a back illuminated sensor where the wiring and logic is behind the actual sensor cells. I got the impression that this arrangement gives about one step in sensitivity.

On the other hand, DR is depending on well capacity and readout noise. Well capacity seems to be in the same neighborhood in P65 and and 20-25 MP CMOS according from what I have seen. MFDBs used to have higher readout noise than DSLRs but this may not be the case with the present generation of digital backs.

It's a bit odd to me that native ISO for CMOS tends to be around 200, while MFDB-s are significantly lower. Having about the same well capacity and "quantum efficiency" I would expect that native ISO would be about the same. Interestingly, the Leica S2 has a native ISO of 160 with an option to "pull" to reduce ISO.

One area which has not been discussed but may explain some differences is the efficiency of the color filter grid. If the RGB filters are narrow and have steep gradients saturated colors may be easier to achieve. This would also reduce ISO. On the other hand, in our own vision there is a significant overlap between spectra sensitivity  of the receptors, so it may be easier to reproduce the metameric  behavior of the human vision with more overlapping sensels.

[attachment=20727:ColorResponse.jpg]

Best regards
Erik

Maybe not quite that simple, since the actual light sensitive area on each of the photo sites is quite a bit different. I believe only 10% of the surface of each CMOS site is light sensitive, whereas around 30% of each site on a CCD is light sensitive.

[fredjeang]

My last post was a premonition saying "we will soon have graphics"....
And you just did it Erik.  

Why can't we have once for awhile real pictures comparaisons in real work situations, made in such scientifical way that it will be unquestionable?
Instead of graphics and theories.
That would just put an ultimate light on the endless topic.
Anybody with a D3s and Phase or Hasselblad for doing this ??

Regards,

Fred.

Wayne,

I think you are right on the issue, although the percentages may be a bit higher according to my reading. CMOS sensors normally have microlenses, which compensate for part of the difference between CMOS and CCD. Sony works on a back illuminated sensor where the wiring and logic is behind the actual sensor cells. I got the impression that this arrangement gives about one step in sensitivity.

On the other hand, DR is depending on well capacity and readout noise. Well capacity seems to be in the same neighborhood in P65 and and 20-25 MP CMOS according from what I have seen. MFDBs used to have higher readout noise than DSLRs but this may not be the case with the present generation of digital backs.

It's a bit odd to me that native ISO for CMOS tends to be around 200, while MFDB-s are significantly lower. Having about the same well capacity and "quantum efficiency" I would expect that native ISO would be about the same. Interestingly, the Leica S2 has a native ISO of 160 with an option to "pull" to reduce ISO.

One area which has not been discussed but may explain some differences is the efficiency of the color filter grid. If the RGB filters are narrow and have steep gradients saturated colors may be easier to achieve. This would also reduce ISO. On the other hand, in our own vision there is a significant overlap between spectra sensitivity  of the receptors, so it may be easier to reproduce the metameric  behavior of the human vision with more overlapping sensels.

[attachment=20727:ColorResponse.jpg]

Best regards
Erik

[barryfitzgerald]

Experience has shown me however that the 1DSMK3 has significantly better DR than film (and I used to shoot film) so I raise an eyebrow at the comment that film has better DR than a DSLR (because it doesn't in my experience).

It's not just about the DR number, it's "where the DR is" Regarding negative film, it's got a pretty impressive roll off in the highlights, digital is the reverse..it's mostly all in the shadows. Pulling up hard shadows wise, watching the highlights to avoid clipping..I can get not too far from neg film..but it's not really the same, hues and colours shifting can be an issue. Obviously raw and low ISO are a must.

Films vary in DR too, so a blanket statement cannot hold any water. I've serious doubts any DSLR at any price can match some of the b&w films either, FP4 has a simply massive latitude, over and underexposure wise. The only company to seriously attempt good DR via a sensor is Fuji, shame we don't see more of this.
But more to the point..in many cases having a big highlight latitude is more useful. If we added 2-3 stops more highlight end on most DSLR's, you'd hear next to no complaints about burnt out highlights.
I'm glad were talking about DR though, it's an important point, and often takes a back seat to "resolution"