Big Sensors versus Small Sensors

[Ray]

It's always seemed a bit absurd to me the way battle lines are drawn between MFDB and 35mm format when any discussion about comparative image quality is started.


It should be apparent to everyone who's been interested in photography for any significant period of time, that there's a strong connection between sensor size and image quality. Generally, the bigger the sensor, the better the image quality, at least in some major respects in not in all respects.

No-one could sensibly argue that a P&S camera produces image quality equal to that from an APS-C format. No-one could sensibly argue that an APS-C format produces image quality on a par with full frame 35mm, and likewise, no-one can sensibly argue that full frame 35mm produces image quality on a par with a DB which has two or more times the sensor area of 35mm.

If a sensor collects double the amount of light because it has double the area of another sensor, one would expect approximately a 1 stop increase in DR. If it has 4x the area, one could expect a 2 stop increase in DR, 8x the area 3 stops, 16x the area 4 stops and so on.

That progression of course assumes that all other factors contributing to DR are on an equal technological footing, and they rarely are. CMOS sensors are different to CCD sensors. My impression is that the photon-collecting diode on the CMOS sensor is smaller than the equivalent diode on a CCD sensor of equal pixel pitch.

That fact alone might explain why a DB, with double the sensor area of 35mm format, might have more than a one stop DR advantage. If each photon-collecting photodiode on the CCD pixel (of equal pitch) is double the area of the equivalent photodiode on a CMOS pixel, one might expect a 2 stop DR advantage, at base ISO.

However, the reason the photodiode on the CMOS pixel is smaller is in order to accommodate other processing devices on the sensor which improve signal-to-noise before the signal is digitised. I would gess that this is why, at the pixel level, a D3X has substantially higher DR than a P65+.

The D3X pixel is exactly the same size as that of the P65+. It's a testament to the technological prowess of Nikon and Sony that they've succeeded in gaining greater DR from a photodiode which is probably smaller than the photodiode on a much more expensive DB of equal pixel pitch.

However, the P65+ has many more pixels than the D3X. Comparing images of equal size, the increased DR of the D3X is marginal. Only 2/3rds of a stop at an 8"x12' print size.

But there's a question here which I've never seen addressed. When downsizing both images to an 8x12' size, as DXO does, one is throwing away image information from both cameras, in the example of the D3X and P65+, but one is throwing away more information from the P65+ image.

If one were to interpolate the D3X image to the same file size as the P65+ and then compare DR, what would be the result?

If one defines DR as the amount of meaningful image information in the deep shadows of an ETTR exposure, then it stands to reason that the P65+, with its significantly higher pixel count, might have a higher DR than the interpolated D3X image. At a guess, instead of 2/3rds of a stop lower DR (than the D3X) it might have 2/3rds of a stop higher DR. What do you think?

[Rory]

Ray

I don't think there were battle lines drawn - at least by those questioning the DR statements.  However, there were some pretty extra-ordinary statements made by Mark and Michael - two very well respected photographers.  As a consequence they were asked for evidence, which Michael suggests he and Mark are working on.  

With regard to your discussion on bigger sensors being better than smaller ones - that may well be true for overall image quality, but my understanding is it has nothing to do with dynamic range, which is a function of the individual sensor "pixels" - and is generally a function of the capture area and the on-chip processing of the individual sensors.

I own a D700 right now, and in an informal test shooting inside and outside through a window, I was able to hold detail through between 8-9 stops.  I think the D700 is a little better than average for DSLRS, so Michael and Mark's 6-7 stops of "usable DR" for DSLRs is probably not far off the mark (sorry Mark, that just flowed off my keyboard).  The question is whether the MF can get 13 stops usable DR - something I seriously doubt until I see it.

In the end we all benefit from these debates and the internet keeps everyone honest.

Cheers
Rory

[ErikKaffehr]

Hi,

I'm not really sure about this. Photographers see differences and those differences may be hard to explain. It may be that sometimes the talk is about microcontrast sometimes about tonality and now DR.

It is a bit unfortunate that DR is an engineering having an exact definition. So we start to talk about a usable DR, how do we define that.

The cameras are differently used.

- Mark has his P65 on an Alpa using a laser rangefinder quite often.

- MFDBs are used at low ISO - DSLRs are often used at relatively high ISO

- Personally I think lenses matter. DSLR lenses use to be complex designs. No one buys a 28/2.8 lens for a DSLR (well except Lloyd Chambers ;-) large aperture lenses contain a lot of extra glass. MFDBs used to have more conservative design and may be better finished.

My guess is that the DxO tests describe the sensors pretty well.

Comparing DSLRs and MFDBs is not that easy. Taking two different systems to the field is not very practical. For controlled conditions you would probably need a studio setup. With a well controlled studio setup you probably get into similar conditions DxO is using. Now, DxO is measuring on "raw-data". Photographers would typically use raw-converters and that induces a difference.

Images from Phase One backs contain a lot (around one megabyte?) of proprietary calibration information for each individual back, as explained in one of the LLVJ DVDs (I try to find out which). The phase converter can use this information to it's advantage.

Best regards
Erik

It's always seemed a bit absurd to me the way battle lines are drawn between MFDB and 35mm format when any discussion about comparative image quality is started.


It should be apparent to everyone who's been interested in photography for any significant period of time, that there's a strong connection between sensor size and image quality. Generally, the bigger the sensor, the better the image quality, at least in some major respects in not in all respects.

No-one could sensibly argue that a P&S camera produces image quality equal to that from an APS-C format. No-one could sensibly argue that an APS-C format produces image quality on a par with full frame 35mm, and likewise, no-one can sensibly argue that full frame 35mm produces image quality on a par with a DB which has two or more times the sensor area of 35mm.

If a sensor collects double the amount of light because it has double the area of another sensor, one would expect approximately a 1 stop increase in DR. If it has 4x the area, one could expect a 2 stop increase in DR, 8x the area 3 stops, 16x the area 4 stops and so on.

That progression of course assumes that all other factors contributing to DR are on an equal technological footing, and they rarely are. CMOS sensors are different to CCD sensors. My impression is that the photon-collecting diode on the CMOS sensor is smaller than the equivalent diode on a CCD sensor of equal pixel pitch.

That fact alone might explain why a DB, with double the sensor area of 35mm format, might have more than a one stop DR advantage. If each photon-collecting photodiode on the CCD pixel (of equal pitch) is double the area of the equivalent photodiode on a CMOS pixel, one might expect a 2 stop DR advantage, at base ISO.

However, the reason the photodiode on the CMOS pixel is smaller is in order to accommodate other processing devices on the sensor which improve signal-to-noise before the signal is digitised. I would gess that this is why, at the pixel level, a D3X has substantially higher DR than a P65+.

The D3X pixel is exactly the same size as that of the P65+. It's a testament to the technological prowess of Nikon and Sony that they've succeeded in gaining greater DR from a photodiode which is probably smaller than the photodiode on a much more expensive DB of equal pixel pitch.

However, the P65+ has many more pixels than the D3X. Comparing images of equal size, the increased DR of the D3X is marginal. Only 2/3rds of a stop at an 8"x12' print size.

But there's a question here which I've never seen addressed. When downsizing both images to an 8x12' size, as DXO does, one is throwing away image information from both cameras, in the example of the D3X and P65+, but one is throwing away more information from the P65+ image.

If one were to interpolate the D3X image to the same file size as the P65+ and then compare DR, what would be the result?

If one defines DR as the amount of meaningful image information in the deep shadows of an ETTR exposure, then it stands to reason that the P65+, with its significantly higher pixel count, might have a higher DR than the interpolated D3X image. At a guess, instead of 2/3rds of a stop lower DR (than the D3X) it might have 2/3rds of a stop higher DR. What do you think?

[deejjjaaaa]

No one buys a 28/2.8 lens for a DSLR

you are very wrong... you probably need for example to check dslr forums where people sell/buy used glass... you will be very suprised, unless that suggestion of yours was really a joke akin to "6 stops of DR"

[JeffKohn]

- Personally I think lenses matter. DSLR lenses use to be complex designs. No one buys a 28/2.8 lens for a DSLR (well except Lloyd Chambers ;-) large aperture lenses contain a lot of extra glass. MFDBs used to have more conservative design and may be better finished.

I don't think you can generalize like this. Assuming the comparison is between best-of-breed lenses for each system, I find it highly unlikely there's a significant difference in the "dynamic range" of the lenses. Today's best lenses have aspherical and low-dispersion elements, as well as extremely advanced coatings to reduce flare and ghosting.  

There are complex lens designs in both formats. While a particular lens might have flare issues when shooting straight into the sun, more often than not this can be avoided, in which case I don't think the lens is going to be a limiting factor in dynamic range.

As for what DSLR users do or do not use, I think you'll find that many folks trying to get the most out of their high-res DSLR's are using primes. I know I shoot most of my landscapes with a 5-prime kit, of which only one of the lenses is faster than f/2.8 (and I'm quite confident the Zeiss 100 Makro-Planar has plenty of contrast despite its f/2 aperture).

[michael]

In case anyone hasn't seen it, the following was added to the review yesterday...

Paragraph Removed – Editor

The struck-out paragraph below was part of the original article. It caused quite a bit of controversy on this site's forum and elsewhere. I initially added a comment to the bottom of the article, but that wasn't sufficient. Too many people's favourite ox had already been gored.

Please consider the paragraph below to be removed. There's no point in actually removing it, because once on the net, things last forever, and undoubtedly some zealots would consider it a coverup if we did so.



The reason that Mark and I have decided to remove it is not because we don't agree with its basic sentiment, but because it is serving as a distraction for the main point of the review, which is a comparison between two different medium format backs.

There is wide agreement among photographers that use or have used both formats that MF has an advantage of several F/stops in DR versus the small cameras. The precise number will vary depending on the specific camera and back being compared as well as the comparison methodology, but the difference is quite noticeable in actual images. From 30 feet away? Maybe not. Let's just chalk that phrase up as a bit of editorial hyperbole rather than something intended to be taken literally.

The issue of the differences between medium format and 35mm is a fascinating one though, and Mark and I intend on pursuing it in greater depth in the days ahead, and with more rigour than with a throw-away line or two.

[barryfitzgerald]

Just wandering a little, very interesting to see Pentax back in the medium format business. 40mp 645D.
Price wise looks very competitive to rivals. I'm sure we'll see more on this one in due time.

[GianlucaLastoria]

You had to remove that comment, since it was at least contradictory with the article comparing the printout of a Canon G10 (not a 1Ds Mark-whatever) and a MF, where you stated that 40% of the people were not able to tell correctly which print was from which camera....

http://www.luminous-landscape.com/reviews/kidding.shtml

[ErikKaffehr]

Hi,

Sorry for that.

Let's put it this way. It seems hard to come up with any explanation that MFDBs would have more than one stop of advantage in DR. This may even be less, because DSLRs are using micro lenses. Photographers still see differences interpreted as DR. Not all light passing trough the lens is actually building image some part is scattered and shows up as flare. Figures I have seen may be around one percent. Now, one percent of flare would limit DR to about seven stops. Would flare amount to 0.1% about 10 stops of DR would be possible. Now, this percentage is of course dependent on how flare is calculated. It is a percentage of what?!

MFDB lenses used to be quite conservative designs. Normal lenses at around f/2.8 can be built with a small number of elements, a typical double Gauss normal lens usually has 6 elements in five groups. The lens elements are normally pretty small and fixed, they don't move around. Older lenses used to have metal tubing, well blackened and with internal baffles to keep the light from hitting the walls of the internal tubing. Modern lenses have more elements and may of them may moving around for zoom or internal focus. The elements may also be larger or more curved which may make them harder to fit inside the tubing.

Aspheric lenses don't reduce flare, but can improve on spherical aberration and fine detail contrast.

The Carl Zeiss 100/2 Macro Planar is one the finest lenses. Bernard Languillier, a frequent poster on this forum is using that lens. But that's certainly not the lens most people would use. Most people would use a Canon 24-70/2.8, a Canon 24/1.4L or the corresponding Nikon lenses. I use a Sony 24-70/2.8, mostly. I also have Sigma 12-24/4.5-5.6, Minolta 20/2.8, Minolta 50/1.4, Minolta 80-200/2.8 APO, Sony 70-300/4.5-5.6, Minolta 300/4 APO and 400/4.5 APO. I don't have a Zeiss 85/1.4 or a 135/1.8, sure they are great lenses. But I really want to have the flexibility of the zooms and fast autofocus.

Best regards
Erik

I don't think you can generalize like this. Assuming the comparison is between best-of-breed lenses for each system, I find it highly unlikely there's a significant difference in the "dynamic range" of the lenses. Today's best lenses have aspherical and low-dispersion elements, as well as extremely advanced coatings to reduce flare and ghosting.  

There are complex lens designs in both formats. While a particular lens might have flare issues when shooting straight into the sun, more often than not this can be avoided, in which case I don't think the lens is going to be a limiting factor in dynamic range.

As for what DSLR users do or do not use, I think you'll find that many folks trying to get the most out of their high-res DSLR's are using primes. I know I shoot most of my landscapes with a 5-prime kit, of which only one of the lenses is faster than f/2.8 (and I'm quite confident the Zeiss 100 Makro-Planar has plenty of contrast despite its f/2 aperture).

[douglasf13]

Hi,

Sorry for that.

Let's put it this way. It seems hard to come up with any explanation that MFDBs would have more than one stop of advantage in DR. This may even be less, because DSLRs are using micro lenses. Photographers still see differences interpreted as DR. Not all light passing trough the lens is actually building image some part is scattered and shows up as flare. Figures I have seen may be around one percent. Now, one percent of flare would limit DR to about seven stops. Would flare amount to 0.1% about 10 stops of DR would be possible. Now, this percentage is of course dependent on how flare is calculated. It is a percentage of what?!

MFDB lenses used to be quite conservative designs. Normal lenses at around f/2.8 can be built with a small number of elements, a typical double Gauss norma lens usually has 6 elements in five groups. The lens elements are normally pretty small and fixed, they don't move around. Older lenses used to have metal tubing, well blackened and with internal baffles to keep the light from hitting the walls of the internal tubing. Modern lenses have more elements and may of them may moving around for zoom or internal focus. The elements may also be larger or more curved which may make them harder to fit inside the tubing.

Aspheric lenses don't reduce flare, but can improve on spherical aberration and fine detail contrast.

The Carl Zeiss 100/2 Macro Planar is one the finest lenses. Bernard Languillier, a frequent poster on this forum is using that lens. But that's certainly not the lens most people would use. Most people would use a Canon 24-70/2.8, a Canon 24/1.4L or the corresponding Nikon lenses. I use a Sony 24-70/2.8, mostly. I also have Sigma 12-24/4.5-5.6, Minolta 20/2.8, Minolta 50/1.4, Minolta 80-200/2.8 APO, Sony 70-300/4.5-5.6, Minolta 300/4 APO and 400/4.5 APO. I don't have a Zeiss 85/1.4 or a 135/1.8, sure they are great lenses. But I really want to have the flexibility of the zooms and fast autofocus.

Best regards
Erik

 You have touched on an often overlooked and critical point about DR.  DR is often lens, not sensor, limited.  Like you say, it's all about internal reflections and flare.  Simple prime lenses with few elements/groups and good internal baffling generally allow more DR than a complicated zoom with a UV filter on it.

[ErikKaffehr]

Hi,

I made some similar experiments with APS-C and full format 135 DSLRs. Sometimes the difference may be hard to see in prints. Depends much on detail size.

I touch on the issue in this article: http://echophoto.dnsalias.net/ekr/index.ph...xels-do-we-need

This page has some interesting links: http://echophoto.dnsalias.net/ekr/index.ph...vs-mfdb-vs-film

Best regards
Erik

You had to remove that comment, since it was at least contradictory with the article comparing the printout of a Canon G10 (not a 1Ds Mark-whatever) and a MF, where you stated that 40% of the people were not able to tell correctly which print was from which camera....

http://www.luminous-landscape.com/reviews/kidding.shtml

[John Camp]

Michael and Mark say they are going to do more work and come back to this topic, and I hope they do, and get it done before the new round of Canon and Nikon and the new Pentax MF high-res cameras are released...

I have a problem with "real world" discussions, however. I'm not a scientist, but I have studied the philosophy of science, and would have interesting and detailed discussions about scientific method with my late wife, who had a PhD in immunology, which is an intricate and complicated and often confusing field of study. Ultimately the problem with "real world" views is that they confuse issues. It's quite possible that Mark's anecdote about seeing differences in a print at thirty feet is entirely accurate -- in that people can see differences - but those differences don't really involve DR, even though people sincerely believe they do. That simply has to do with the way the brain works -- a much large sensor delivers, say, terrific microcontrast and subtle color across a wide dynamic range, and people may assume that the dynamic range is wider that it actually is, because they are being influenced by other factors. Basic color theory texts routinely demonstrate "perceived" differences in DR by placing different colors adjacent to a test color...and the test color's brightest or dullness seems to fluctuate depending upon the adjacent color, although that color does not change at all. Separating out these exterior influences can be nearly impossible in "real world" views.

The other thing that I've learned as a regular reader of Nature, an addition to my relationship with a serious scientist, is that test results and measurements often come out the way the testers wish they would...so it's perfectly possible that serious engineers for MF companies believe their dynamic range is 6-7 stops wider than 35mm-equiv digital, because they *wish* that were true. In my experience, the best results come from sources who don't care about the outcome of the tests...one reason, for example, that I've been more than a bit wary about the Tour de France drug-testing methods involving people like Floyd Landis. I would have been much more confident of the outcome if the tests were done, say, in Japan.

So, I hope if this is further explored, that the testing methods will be as rigorous as possible.

JC

[fredjeang]

Michael and Mark say they are going to do more work and come back to this topic, and I hope they do, and get it done before the new round of Canon and Nikon and the new Pentax MF high-res cameras are released...

I have a problem with "real world" discussions, however. I'm not a scientist, but I have studied the philosophy of science, and would have interesting and detailed discussions about scientific method with my late wife, who had a PhD in immunology, which is an intricate and complicated and often confusing field of study. Ultimately the problem with "real world" views is that they confuse issues. It's quite possible that Mark's anecdote about seeing differences in a print at thirty feet is entirely accurate -- in that people can see differences - but those differences don't really involve DR, even though people sincerely believe they do. That simply has to do with the way the brain works -- a much large sensor delivers, say, terrific microcontrast and subtle color across a wide dynamic range, and people may assume that the dynamic range is wider that it actually is, because they are being influenced by other factors. Basic color theory texts routinely demonstrate "perceived" differences in DR by placing different colors adjacent to a test color...and the test color's brightest or dullness seems to fluctuate depending upon the adjacent color, although that color does not change at all. Separating out these exterior influences can be nearly impossible in "real world" views.

The other thing that I've learned as a regular reader of Nature, an addition to my relationship with a serious scientist, is that test results and measurements often come out the way the testers wish they would...so it's perfectly possible that serious engineers for MF companies believe their dynamic range is 6-7 stops wider than 35mm-equiv digital, because they *wish* that were true. In my experience, the best results come from sources who don't care about the outcome of the tests...one reason, for example, that I've been more than a bit wary about the Tour de France drug-testing methods involving people like Floyd Landis. I would have been much more confident of the outcome if the tests were done, say, in Japan.

So, I hope if this is further explored, that the testing methods will be as rigorous as possible.

JC

Thank you John,
That is indeed an interesting point of view. I read your post with attention and I think you brought a very interesting focus on the matter.
I tend to agree in many of the points you made.

Cheers,

Fred.

[PierreVandevenne]

Microlenses increase QE and are one of the main factors behind the better high ISO peformance of DSLRs. DR is unaffected: the well capacity is unchanged, the well just fills faster, and the read noise remains the same.
Hardware (on chip) binning is a sure method to increase DR. That's what "real" stuff uses when maximizing DR is required (http://www.marresearch.com/products.mx-series.html). Software binning can improve DR somewhat as well (see bottom of this page http://www.theta-system.com/sis.html) but that depends on a few other factors. Since it seems polite to make a difference between engineering QE, DR and photographic "high iso" sensitivity and "photographic" DR, "photographic binning" can play a role as well. If you shoot aunt Eunice with a DSLR and a MFDB and print the portraits at the same size or compare them on the same screen, you've "binned" the MFDB sensor relatively to the DSLR  and probably gained a bit of DR/transition smoothness in the process.

Anyway, one of the best analysis of the issues involved is Emil's work, which was posted here earlier.

http://theory.uchicago.edu/~ejm/pix/20d/te...oise/index.html

Of course, lenses do play a very significant role: the sensor doesn't sample Aunt Eunice, it samples whatever image the lens provides. Engineering DR remains unaffected, but our perception of the rendered DR versus the actual DR of the scene is what matters most...


PS: I couldn't help thinking that someone who glanced quickly at Emil's article and charts might have had the impression that DSLRs DR was in the 7-8 stops range. ;-)

[Ray]

With regard to your discussion on bigger sensors being better than smaller ones - that may well be true for overall image quality, but my understanding is it has nothing to do with dynamic range, which is a function of the individual sensor "pixels" - and is generally a function of the capture area and the on-chip processing of the individual sensors.

Rory, it seems clear that DR is a function of both individual pixels and over all sensor size. Sorry to keep referring to DXO test results, but there's an interesting and relevant comparison between the 8mp Canon 20D and the recent 5D2 at:  

http://www.dxomark.com/index.php/eng/Image.../(brand2)/Canon

Just as the pixel size of the P65+ is the same as that of the D3X, the pixel size of the 5D2 is the same as that of the 20D, except the 5D2 and 20D employ very similar CMOS technology so the relationship between DR and sensor size is less likely to be affected by other design factors.

What I find interesting is just how close the DR of the 20D pixel is to that of the 5D2 pixel despite the intervening years of technological development. It's almost as though Canon took the old 20D sensor and just multiplied its area by 2.6 to get the full frame 5D2.

The DR of the 5D2 pixel is very marginally better, by about 1/4th of a stop all the way up to ISO 3200 which is the highest ISO setting on the 20D. The slight improvement is possibly due to a further narrowing of the gap between microlenses and perhaps a slight increase in the size of the photon-collecting diode in the 5D2 pixel. However, the tonal range is exactly the same, and very susrprisingly the color sensitivity of the 20D pixel is actually slightly better than that of the 5D2.

Now DXO Mark also provide results at a normalised print size of 8x12" at 300ppi, which so happens to be the exact print size from a 20D at 100%. At that print size, the performance of the 5D2 takes a leap. All the parameters of SNR, DR, tonal range, color sensitivity are significantly better than the 20D. DR is close to one stop better, for example.

One might reasonably deduce that a P65+ would have close to a 1 stop DR advantage over the D3X when the P65+ file is downsized to the same size as the D3X file provided that the technologies employed in both sensors are the same or very similar, which of course they are not.

[Rory]

What I find interesting is just how close the DR of the 20D pixel is to that of the 5D2 pixel despite the intervening years of technological development. It's almost as though Canon took the old 20D sensor and just multiplied its area by 2.6 to get the full frame 5D2.

The DR of the 5D2 pixel is very marginally better, by about 1/4th of a stop all the way up to ISO 3200 which is the highest ISO setting on the 20D. The slight improvement is possibly due to a further narrowing of the gap between microlenses and perhaps a slight increase in the size of the photon-collecting diode in the 5D2 pixel. However, the tonal range is exactly the same, and very susrprisingly the color sensitivity of the 20D pixel is actually slightly better than that of the 5D2.

Now DXO Mark also provide results at a normalised print size of 8x12" at 300ppi, which so happens to be the exact print size from a 20D at 100%. At that print size, the performance of the 5D2 takes a leap. All the parameters of SNR, DR, tonal range, color sensitivity are significantly better than the 20D. DR is close to one stop better, for example.

I see your point Ray.  I presume the interpolation of the larger files reduce noise and therefore increase DR.

[Ray]

The other thing that I've learned as a regular reader of Nature, an addition to my relationship with a serious scientist, is that test results and measurements often come out the way the testers wish they would...so it's perfectly possible that serious engineers for MF companies believe their dynamic range is 6-7 stops wider than 35mm-equiv digital, because they *wish* that were true. In my experience, the best results come from sources who don't care about the outcome of the tests...one reason, for example, that I've been more than a bit wary about the Tour de France drug-testing methods involving people like Floyd Landis. I would have been much more confident of the outcome if the tests were done, say, in Japan.

So, I hope if this is further explored, that the testing methods will be as rigorous as possible.

JC

That's a good point, John, and the reason for the necessity of double-blind testing and the repeatability of testing and experimentation by other parties who may not have the same vested interests and agenda.

There's also the complication of choice of RAW converter, the sorts of processing adjustments used and the fact that one particular brand of raw converter may favour one particular brand of camera. Remember RSP (RawShooter premium) that was taken over by Adobe? It used to be my preferred RAW converter for certain landscapes, especially from the 5D.

I preferred it because it gave me results with just a few adjustments of the sliders, which ACR couldn't provide with the same ease. I once tried to emulate an RSP conversion by making as many adjustments in ACR to get the RAW image looking as close as possible, and then making further adjustments to the converted image in Photoshop. I eventually got the ACR conversion looking very similar to the RSP conversion, but it was a lot of work.

I wouldn't expect owners of expensive MFDB equipment to work too hard to get an image from a much less expensive 35mm camera looking almost as good.  

[BernardLanguillier]

I feel that one key aspect in the perception of DR is the way the raw converters handles local contrast.

We know for a fact that both MFDB and high end DSLR have too much DR for a pleasing rendering without some tweaking. Images look flat when you attempts to map say 11 stops of DR on an 8 bit display.

So you need to work with local contract to generate pleasing results.

We know that the highlight/shadow sliders ot leading raw converters do play with local contrast, to the extend that they sometime generate halos similar to what one gets when using Photomatix.

How much of this is automated when you open a P65+ file in C1 is a topic on which I would be interested in getting more information.

Cheers,
Bernard

[Ronny Nilsen]

The other thing that I've learned as a regular reader of Nature, an addition to my relationship with a serious scientist, is that test results and measurements often come out the way the testers wish they would...so it's perfectly possible that serious engineers for MF companies believe their dynamic range is 6-7 stops wider than 35mm-equiv digital, because they *wish* that were true. In my experience, the best results come from sources who don't care about the outcome of the tests...one reason, for example, that I've been more than a bit wary about the Tour de France drug-testing methods involving people like Floyd Landis. I would have been much more confident of the outcome if the tests were done, say, in Japan.

So, I hope if this is further explored, that the testing methods will be as rigorous as possible.

This is a very good point. Science is full of examples of how even large groups of honest and good scientist can fool them self.

The book "The Undergrowth of Science - delusion, self-deception and human frailty" by Walter Gratzer gives many examples of how scientists, and even nations, have failed in their pursue of science.

Ronny

[Alan Goldhammer]

The other thing that I've learned as a regular reader of Nature, an addition to my relationship with a serious scientist, is that test results and measurements often come out the way the testers wish they would...so it's perfectly possible that serious engineers for MF companies believe their dynamic range is 6-7 stops wider than 35mm-equiv digital, because they *wish* that were true. In my experience, the best results come from sources who don't care about the outcome of the tests...one reason, for example, that I've been more than a bit wary about the Tour de France drug-testing methods involving people like Floyd Landis. I would have been much more confident of the outcome if the tests were done, say, in Japan.

So, I hope if this is further explored, that the testing methods will be as rigorous as possible.

JC

My background is in biochemistry and I've done enough lab work over the years and in my current professional career to understand what is good science and what is not.  My read of the DxO data is that it's an engineering approach and there is very little in terms of subjective endpoints to the research.  this is the real key to looking at any research.  Clearly access to data sets and methodology is important for independent corroboration (this the role of the US Food and Drug Administration in reviewing new pharmaceuticals for approval).  

All this being said, there is some work that we all can do.  If you go back to the closed thread, there were some nice posts about possible experiments that can be done (for example, see the Image66 post at:  http://luminous-landscape.com/forum/index....2074&st=160 ).  One can take any of the popular printer evaluation images and do this type of experiment to see what the useful photographic range of a camera might be.  The classic B&W zone exposure test can also be done using a textured mono-color target and expose throughout the range, though this would of course involve a B&W conversion for evaluation.  One could test a prime lens vs a zoom lens to see if there is a major difference as some have postulated.  We could also build a mini data set for various cameras as well.  Providing the weekend doesn't get rained out here in the mid-Atlantic, I'm going to try both approaches using natural light (I don't have any kind of interior set up that I could use) with my Nikon D300 (and maybe even Canon S90) to see what the ranges are.  Will post protocols and results on my website and make RAW files available as well.

Alan