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Author Topic: Canon 6D Mark II: less DR than any smaller sensor camera, even M4/3  (Read 9750 times)

Slobodan Blagojevic

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BJL

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Re: Canon 6D Mark II: less DR than any smaller sensor camera, even M4/3
« Reply #42 on: July 25, 2017, 09:07:29 PM »

There are some strange extremes here. It seems to me that the 6D Mark II (and probably every recent ILC) has more than enough dynamic range for the great majority of photography, including any image that can be printed "straight" rather than with substantial compression of contrast, so it will probably be fine for many users. And I do not agree that maximum DR is "the most important aspect of image quality". But having more DR than slide film is a very low bar for a US$2000 camera: that medium did at times require using graduated ND filters, and people would clearly want to minimize the need for that hack. It is not as if being the cheapest Canon 35mm format DSLR makes this a camera for nothing more than casual snapshots.
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RichDesmond

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Re: Canon 6D Mark II: less DR than any smaller sensor camera, even M4/3
« Reply #43 on: July 25, 2017, 10:39:52 PM »

It it just me, or has this site moved in the DPReview direction in the last year or so?? Seems like a lot brand bashing going on, for no apparent purpose.
Obsessing over a particular technical spec seems just weird here. Lots of ways to make great photos (perhaps I'll eventually figure one out :)), if the new 6D Mark II doesn't suit you then don't buy it. I'm not going to either, but that doesn't make Canon a bad company, or the people who do buy one ignorant dolts.
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shadowblade

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Re: Canon 6D Mark II: less DR than any smaller sensor camera, even M4/3
« Reply #44 on: July 25, 2017, 11:32:50 PM »

SNR (i.e. DR at base ISO), resolution and strength of the colour filters are the three sensor-based factors that affect technical image quality at any given sensor size. Of these, SNR (plus the read noise contribution to noise) is probably the most important. Resolution matters for large prints and heavy cropping, and absolute colour accuracy matters for specialised things like art reproduction, but SNR matters for almost every application. Not just for high-DR situations, but also for image quality in standard DR situations at high ISO (you lose 1 stop of SNR for every step of ISO gain, although the biggest contribution to Canon's low-ISO DR weakness is read noise, rather than a difference in underlying SNR) and standard DR situations in anything other than white light (individual channels can get pushed or pulled by several stops just for white balance).

That said, the 6D2 was never going to be a ground-breaker, and not a good product by which to judge the state of Canon's technology. It's an entry-level full-frame camera, like the D610 and A7ii, designed to be price-competitive against the higher-tier offerings and for users who want to take nice photos in non-challenging lighting conditions, but who don't come close to pushing technical limits either in ISO, DR or AF. For instance, such a sensor or body would be perfect for a studio photographer with complete control over lighting, who has better things to spend money on than a body with unneeded DR, ISO or AF capability. Better to add a few more lights or accessories in that case, or a faster PP workflow.

The 6D2 sensor would have been designed with these users, and cost savings, in mind. Canon still has older fab plants which can make these sensors, but not the newer ones capable of making sensors with column-parallel, on-sensor ADC which have base DR in the same ballpark as sensors from other manufacturers. Better to use these fab plants to make sensors for a product which doesn't need a higher-grade sensor, while saving the higher-grade lines to make 5D4, 80D, 1Dx2 and future 5Dx2 sensors, than to leave them sitting idle while taking up higher-end capacity which could otherwise be making sensors for products which really need them.

I would expect the 5Ds2/other 5Ds replacement to be a much better gauge of the state of Canon's technology than an entry-level body which doesn't even pretend to be aimed at users who push technical boundaries. If it can hit 14 stops of DR (at 1:1 SNR, which is the level DxO uses in testing) while reaching 60MP resolution, it will be a competitive product, irrespective of what Sony brings out.
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shadowblade

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Re: Canon 6D Mark II: less DR than any smaller sensor camera, even M4/3
« Reply #45 on: July 25, 2017, 11:40:10 PM »

Also, I find it interesting how certain groups of photographers like to put down anyone needing higher DR or resolution ('learn to expose properly', 'work on skill/composition,not the technical stuff'), while giving a free pass to those who call for higher ISO (we got by with ISO 400 film), AF (they used to shoot sports with MF) or frame rate (learn to time). Almost invariably, these are people whose subject matter or photographic style don't push technical boundaries and who have little understanding of how these boundaries limit and affect the final output.
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BJL

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Re: Canon 6D Mark II: less DR than any smaller sensor camera, even M4/3
« Reply #46 on: July 26, 2017, 01:43:25 PM »

I agree that greater DR (the real thing, measured at base ISO-speed) is an advantage in some not-uncommon situations, and the 6DII is therefore inferior for some uses, even compared to similarly-priced competitors.

But this is a very strong claim:
SNR (i.e. DR at base ISO), resolution and strength of the colour filters are the three sensor-based factors that affect technical image quality at any given sensor size. Of these, SNR (plus the read noise contribution to noise) is probably the most important.
For example, with the great majority of scenes with SBR about six stops or less, 10 stops of DR is plenty, and there will be no visible difference from having 14 or even 16 stops instead. Any given scene needs "enough" SNR, beyond which any more gives no practical improvement.

Not just for high-DR situations, but also for image quality in standard DR situations at high ISO (you lose 1 stop of SNR for every step of ISO gain, although the biggest contribution to Canon's low-ISO DR weakness is read noise, rather than a difference in underlying SNR) and standard DR situations in anything other than white light (individual channels can get pushed or pulled by several stops just for white balance).
That is not necessarily so, as a graph above shows: the 6DII seems to have no SNR disadvantage at higher ISO speeds.  DR at base-ISO can have a complicated relation to high ISO speed SNR, due to the different ways that different cameras handle read-noise. This relates to the nearly "ISO-less" aspect of some column-parallel ADC approaches.

That said, the 6D2 was never going to be a ground-breaker, and not a good product by which to judge the state of Canon's technology.
Agreed! The 6DII is apparently using Canon's previous generation sensor technology, from before it adopted column-parallel ADC.
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scyth

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Re: Canon 6D Mark II: less DR than any smaller sensor camera, even M4/3
« Reply #47 on: July 26, 2017, 04:17:15 PM »

it will be a competitive product, irrespective of what Sony brings out.

Actually so far Canon by itself is competitive irrespective of what Sony brings out... just because it is established itself... so one can assume that 6D2 might simply outsell any Sony dSLM  ;D
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shadowblade

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Re: Canon 6D Mark II: less DR than any smaller sensor camera, even M4/3
« Reply #48 on: July 26, 2017, 10:22:11 PM »

I agree that greater DR (the real thing, measured at base ISO-speed) is an advantage in some not-uncommon situations, and the 6DII is therefore inferior for some uses, even compared to similarly-priced competitors.

But this is a very strong claim:For example, with the great majority of scenes with SBR about six stops or less, 10 stops of DR is plenty, and there will be no visible difference from having 14 or even 16 stops instead. Any given scene needs "enough" SNR, beyond which any more gives no practical improvement.

Not true, on two accounts.

Firstly, almost any backlit scene, sunrise/sunset landscape or interior scene with light coming through windows will have more than six stops of DR. Not relevant if you exclusively shoot portraits or studio work ('portraits' meaning anything from seated portraits to live sports through an 800mm lens), but common enough that many photographers will encounter it fairly regularly, and some for the majority of shots.

Secondly, even if the scene fits within the dynamic range, higher SNR still means less noise in the shadows, since they are further from the noise floor. Instead of a 20:1 SNR in the shadows, you may have a 400:1 SNR with a higher DR sensor, giving you a cleaner image. This is why HDR/image blending will give you cleaner shadows (in situations where it is practical), even with a high-DR sensor such as the D810 or A7r2.

Quote
That is not necessarily so, as a graph above shows: the 6DII seems to have no SNR disadvantage at higher ISO speeds.  DR at base-ISO can have a complicated relation to high ISO speed SNR, due to the different ways that different cameras handle read-noise. This relates to the nearly "ISO-less" aspect of some column-parallel ADC approaches.

I did mention the read noise contribution. But that still doesn't change the utility of more DR at any given ISO for dealing with colour correction and general post-processing - shooting in incandescent light, blue light or almost anything other than direct sunlight (or an electrical mimic), you can be pushing or pulling a channel by several stops just to get to neutral.

Quote
Agreed! The 6DII is apparently using Canon's previous generation sensor technology, from before it adopted column-parallel ADC.

It's probably a case of getting one last use out of the old production lines, for a product that doesn't really need the newer ones, before shutting them down or upgrading them. This gives them a bit of a buffer, time to set up newer lines for modern sensors, to make personnel changes, etc.
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BJL

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Re: Canon 6D Mark II: less DR than any smaller sensor camera, even M4/3
« Reply #49 on: July 27, 2017, 09:28:37 AM »

@shadowblade, I do not dispute that some photographers have reason to care about what I called the "not un-common" situation of dealing with far more than six stops of SBR—and the 6D2 is not the camera for them.

On the other hand, the 6D2 and all recent ILCs have comfortably better handling of high SBR than slide film, and a lot of good photography has been done with such film without hacks like grad ND filters, so I expect that the 6D2 will meet the needs of many good photographers, but not all.

About the idea that "higher SNR is always an advantage", even in scenes of only moderate SBR: there is an important difference between differences that are measurable versus ones that are visible anywhere short of on-screen pixel peeping.  20:1 SNR in the shadows is imperceptable; some reputable guidelines are that 40:1 in the midtones is "excellent" (as in the ISO SNR40 measure of low-light sensitivity) and the old film ISO speed standard which was based on "film base plus fog" (the film version of the noise floor) being a bit over four stops below the mid-tones.
« Last Edit: July 27, 2017, 09:41:13 AM by BJL »
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shadowblade

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Re: Canon 6D Mark II: less DR than any smaller sensor camera, even M4/3
« Reply #50 on: July 27, 2017, 09:42:26 AM »

@shadowblade, I do not dispute that some photographers are often in the "not un-common" situation of dealing with far more than six stops of SBR—and the 6D2 is not the camera for them. On the other had, it and all recent ILCs have comfortably better handling of high than slide film, and a lot of good photography was done with such film, without hacks like grad ND filters, so I expect that the 6D2 will meet the needs of many good photographers, but not all.

About the idea that "higher SNR is always an advantage", even in scenes of only moderate SBR: there is an important difference between differences that are measurable versus ones that are visible anywhere short of on-screen pixel peeping.  20:1 SNR in the shadows is imperceptable; some reputable guidelines are that 40:1 in the midtones is "excellent" (as in the ISO SNR40 measure of low-light sensitivity) and the old film ISO speed standard which was based on "film base plus fog" (the film version of the noise floor) being four stops below the mid-tones.

On the other hand, there was a reason many photographers used negative film, despite the poorer resolution. Slide film just didn't offer enough dynamic range. Landscapers who shot slide film all carried a case full of GND filters, and often ran into trouble when they had to deal with a non-linear horizon.

High DR - just like high ISO (which is really just the other end of the same spectrum) - lets you capture shots in a much greater variety of situations, particularly those where you don't have complete control of the lighting. Not that you can't capture good shots with a camera with limited DR or ISO - just that you can now capture good shots in situations where, previously, you wouldn't even have bothered taking out the camera. The shots aren't any better, but you can capture them in a far greater range of situations, with better output quality. If all you do is shoot touristy snapshots (if the subject's in focus and the shot's not tilted or motion-blurred, it's good enough) or take portraits in friendly (or controlled) lighting, you probably don't need that latitude. But, the moment you have to deal with adverse lighting (backlighting, darkness or strong contrasts), you want that extra latitude.
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BJL

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Re: Canon 6D Mark II: less DR than any smaller sensor camera, even M4/3
« Reply #51 on: July 27, 2017, 11:25:06 AM »

High DR - just like high ISO (which is really just the other end of the same spectrum)
Not quite: as I pointed out before, some cameras have quite good high ISO performance but not great DR at base ISO speed; in particular this is true of older technology Canon CMOS sensors when compared to the best new sensors with column parallel ADC. For example, the graph in post http://forum.luminous-landscape.com/index.php?topic=118996.msg988691#msg988691 shows that the Canon 6D2 has about the same high ISO speed noise performance as the Nikon D750, but lags by two to three stops at base ISO speed.

I think this is because the older Canon sensors apply "ISO gain" amplification in the transfer from photo-sites to the sensor's edge, and then transport that amplified analog signal to A/D convertors that are off-board, or maybe at the corners of the sensor. Therefore, significant read noise can enter after this analog amplification, and at lower ISO speed settings with less of this analog amplification, this noise has a greater effect on the final signal. In comparison, the modern column-parallel ADC approach has no signal transport between analog gain and ADC, so essentially no noise enters after the analog gain stage.
« Last Edit: July 27, 2017, 11:29:12 AM by BJL »
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shadowblade

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Re: Canon 6D Mark II: less DR than any smaller sensor camera, even M4/3
« Reply #52 on: July 27, 2017, 01:14:46 PM »

I know how DR relates to ISO, and the impact of read noise. I've only been talking about it for the past 8 years, since the 5D2 and A900...

That doesn't change the way DR relates to ISO capability. Read noise mostly causes problems and nonlinearity below ISO 800 or so. A camera with higher DR at ISO 800 will probably retain more detail at ISO 25600 or 51200. Visible noise may differ with default settings, but that is mostly due to varying amounts of NR being applied, and differing NR algorithms - the higher-DR sensor will retain more detail in the RAW file.

Column-parallel ADC doesn't change this relationship - it merely allows the linearity to continue to much lower ISOs. You'd probably start to see some nonlinearity appear again if sensors had greater well depth and could shoot at ISO 12, 6 or 3.
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BJL

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Re: Canon 6D Mark II: less DR than any smaller sensor camera, even M4/3
« Reply #53 on: July 28, 2017, 10:09:32 AM »

I know how DR relates to ISO, and the impact of read noise . . . That doesn't change the way DR relates to ISO capability.
. . .
Column-parallel ADC doesn't change this relationship - it merely allows the linearity to continue to much lower ISOs.
I think that your last point about "linearity failure" is also my point: these older generation Canon sensors have a failure in the linear "one stop of SNR for each stop of ISO speed" pattern at lower ISO speeds, leading to a worse DR there than is the case with newer, better approaches. This is nicely illustrated by the above 6D2 vs D750 comparison graph, which shows substantially lower "photographic DR" at base ISO speed but not worse SNR at high ISO speeds.

Perhaps one issue is the difference between what I will call "photo-site dynamic range"—the ratio between full well capacity and dark noise level before read-out—and the measures we actual get, which include other "downstream" noise sources that have a sensor-dependent relationship to ISO speed. If the only noise were that present in photo-sites (photon shot noise plus dark current noise?), then there would be a simple relationship predicting SNR at a given ISO-speed from that "photo-site dynamic range". I seem to remember that studies of Canon sensors some year ago (when they were the start of the art) showed that the DR of the photo-sites themselves was substantially higher than the usual measurements give, due to noise entering later in the process. People complained then about Canon squandering the potential for better low ISO performance—and they still are!
« Last Edit: July 28, 2017, 10:14:27 AM by BJL »
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Bernard ODonovan

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Re: Canon 6D Mark II: less DR than any smaller sensor camera, even M4/3
« Reply #54 on: July 31, 2017, 04:33:05 PM »

Amazing! Brits used to be a skinny nation ;)

The first video was set in South Africa...

The second video had our new Kate Moss...  ;)

You may prefer this review:

https://m.youtube.com/watch?v=wenD1Nr8ygo


Here is an infomercial:

https://m.youtube.com/watch?v=eeezLCMWt10
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Slobodan Blagojevic

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Re: Canon 6D Mark II: less DR than any smaller sensor camera, even M4/3
« Reply #55 on: July 31, 2017, 07:38:05 PM »

... You may prefer this review:

https://m.youtube.com/watch?v=wenD1Nr8ygo
...

But of course, if only because she is from my home country, from the same part as Melania :)

Paulo Bizarro

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Re: Canon 6D Mark II: less DR than any smaller sensor camera, even M4/3
« Reply #56 on: August 01, 2017, 05:25:28 AM »

Given all this talk about how the sensor on the 6DMKII sucks:

https://translate.google.com/translate?act=url&depth=2&hl=en&ie=UTF8&prev=_t&rurl=translate.google.com&sl=ja&sp=nmt4&tl=en&u=http://cweb.canon.jp/eos/info/6dmk2-delivery/release.html

Apparently, Canon are not able to meet initial demand of the camera plus kit zoom lens. Initial demand is higher than expected. All those poor suckers buying this crappy camera:)

mecrox

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Re: Canon 6D Mark II: less DR than any smaller sensor camera, even M4/3
« Reply #57 on: August 01, 2017, 06:21:08 AM »

Given all this talk about how the sensor on the 6DMKII sucks:

https://translate.google.com/translate?act=url&depth=2&hl=en&ie=UTF8&prev=_t&rurl=translate.google.com&sl=ja&sp=nmt4&tl=en&u=http://cweb.canon.jp/eos/info/6dmk2-delivery/release.html

Apparently, Canon are not able to meet initial demand of the camera plus kit zoom lens. Initial demand is higher than expected. All those poor suckers buying this crappy camera:)

Well they would say that, wouldn't they. To get to the bottom line, would you buy this camera? i wouldn't, not after going through some of the online assessments. I think I could get quite a bit better for my money elsewhere and I also suspect that this camera is going to seem sorely outdated a long time before its natural life cycle is up. It's a trap, in other words. Plenty of people will probably never notice this camera's limits but those who do - landscape shooters, enthusiasts, etc - are going to feel they've been had. The way this camera is configured makes me wonder whether Canon's intention is to issue something whose weaknesses will make it easier to persuade people to upgrade to some $$$ mirrorless camera which does have a modern sensor in two years' time.
« Last Edit: August 01, 2017, 06:53:33 AM by mecrox »
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Paulo Bizarro

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Re: Canon 6D Mark II: less DR than any smaller sensor camera, even M4/3
« Reply #58 on: August 01, 2017, 08:57:45 AM »

Well they would say that, wouldn't they. To get to the bottom line, would you buy this camera? i wouldn't, not after going through some of the online assessments. I think I could get quite a bit better for my money elsewhere and I also suspect that this camera is going to seem sorely outdated a long time before its natural life cycle is up. It's a trap, in other words. Plenty of people will probably never notice this camera's limits but those who do - landscape shooters, enthusiasts, etc - are going to feel they've been had. The way this camera is configured makes me wonder whether Canon's intention is to issue something whose weaknesses will make it easier to persuade people to upgrade to some $$$ mirrorless camera which does have a modern sensor in two years' time.

Oh my... as I said many posts above, I have shot with the 6D, and the 5DMKII before that. I actually shoot a lot of landscape, travel, people. I was never in a situation where I thought: gee, if only I had a camera with better X, Y, or Z parameter. These entry-level FF cameras are actually very good to use and shoot with.

I only moved from Canon to Sony A7 system, because the system has matured enough, and I can carry a smaller and lighter backpack without compromising on quality. Even today, I use a A7 and A7II; apparently Sony has issued better stuff since these two were the latest and greatest. But I don't go for that, I just buy judiciously, if stuff works fine for me, then that is that.

NancyP

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Re: Canon 6D Mark II: less DR than any smaller sensor camera, even M4/3
« Reply #59 on: August 01, 2017, 11:08:06 AM »

So, Paulo, what is your typical kit now and its weight, vs your similar focal length kit with the 6D and its weight?
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