DR from 5Ds will be 2 stop better then 7D mk II
- Thread starter etto72
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Well if the new sensor design is already operating at significantly lower temps then I wouldn't think any additional ventilation or heat sinking would be necessary.
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PureClassA said:
I think the reason it's operating at lower temps is due to some kind of active cooling. Canon was working on that a while ago, and it seems they may have finally put the technology to use. Especially of "significantly" means at or below ambient...for that to be the case, some kind of active cooling (best thing that comes to mind is heat pipes) would definitely be necessary. If the sensor maintains a below ambient temperature, something like a peltier would have to be used...but that draws a LOT of power (they aren't very efficient, just very effective)...
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fjrista said:
I guess I'm wondering if cutting out extra amplification needed for high ISOs didn't just itself eliminate the heat. If it's not being produced to begin with... That said you put a much funnier picture in my head of an NItros Oxide forced induction system on the body. Little blue NOS tank and a ram air scoop ;D
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Used to build a lot of desktop computers and I remember trying one of the first liquid cooling heat sink systems on (if memory serves) one of the first AmD Athalons. Pretty neat device and it damn sure looked cool in the tower case. Neon blue and everything
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PureClassA said:
I don't think the elimination of high ISO options is going to affect temperature. I am pretty sure the reason they did that is because of the stronger CFA, which reduces EQE. Most of the DR discussion has to do with using the camera at ISO 100, so high ISO wouldn't factor into the picture anyway.
If the sensor is "significantly" cooler, though, that seems to me to imply that Canon has either employed or devised some way of actively removing heat from the sensor, to at the very least bring it within the realm of ambient. Maybe they designed something to bring it below ambient without the poor efficiency of a peltier. If they did, that would certainly help with the dark current...but, if the 5Ds has the same low dark current as the 7D II...I don't really know what that would do. The 7D II has such low dark current that you wouldn't get any noise from dark current at all under normal conditions unless temperatures were extremely high. The only other time the 7D II has any issues with dark current is when doing long exposures, but most photography is sub-second exposure.
That once again brings us back around to: read noise. :\ I really hope they reduced it by a very significant amount...but even if it's still 6.5e- (half what I'm predicting), that would bring us to 12.2 stops of DR, which is a stop improvement. (It would also entirely invalidate the "same DR as the 5D III unless you use special sauce measurements" claim...)
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Well the guys testing it are obviously seeing some sort of not insignificant improvement, but of course if they release any RAW files and get caught that would be the end of their cozy relationship with Canon. I'm hoping they will be allowed sooner than later to show some samples but knowing Canon, they will play it close to the vest. I'm sure there will be more tweaks between now and June. Even that makes me wonder if they are pushing the release that far back as a red herring to Sony and Nikon to make them show their cards. I'm not betting on it, but I wouldn't be surprised if we see this camera show up a little earlier than they are suggesting right now.
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PureClassA said:
There is perception and fact. I think a lot of the "significant improvement" will ultimately pan out to be feelings about how the files perform in an editor. They are also likely biased by each tester's tolerance for noise in the past. Banding certainly cut into people's tolerance levels in the past, so some people wouldn't do even as much shadow pushing as I have (and I don't do all that much with Canon files). The 5Ds is bound to have lower banding than the 5D III...which may mean these testers are more willing to push shadows than they have in the past. That wouldn't necessarily mean they had more DR, though.
The real test will be direct head-to-head comparisons with images that actually are 13.8 stops. I think in relative terms, the 5Ds probably won't exhibit anything quite so significant as a 1.5-2 stop improvement. In raw testing, I could see it getting a quarter to a third stop higher dynamic range measure, barring some cool new innovation or much lower read noise than the 7D II. If it DOES have much lower read noise, then we've simply been given bad information in regards to the 5Ds having the same DR as the 5D III (and I'd be happy to see that be the case!)
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psolberg said:
No, he is doing exactly what everybody else is doing, repeating the comments from Canon techs that say exactly that, the 5DS DR is the same/equivalent to the 5D MkIII. There is no mystery in that and he knows nothing that is not public knowledge.
The DR of the 5DR/S IS THE SAME as the 5D MkIII, there is no discussion on that, the only point of interest is the Canon comment that there is improved shadow and highlight latitude. Some say those two comments contradict each other, I think the first is worded ambiguously enough that both might well be true.
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privatebydesign said:
Interesting. I'm sure he'll carry out his usual tests so I look forward to finding out where this new gear lands. He nailed the banding issues on the prior canon bodies so if one person can call it fixed, it should be this guy.
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privatebydesign said:
I'm still puzzled about the definition of dynamic range (I'm sure we can agree it's about what we find in the raw image data, and not somewhere up the pipeline or at the sensor before it's usable).
Is dr the noise floor (however that is defined?) *excluding* banding, or must it include banding because it's very hard if impossible to remove in post and thus cannot be counted into the "dynamic range"?
Depending on this definition, the 7d2-based 5ds probably will have more dr than 5d3 (as in "less banding") or it won't (unlike the ff 6d/1dx which really improve upon the 5d3). Or am I mistaken? What do the dr experts say?
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Marsu42 said:
The noise floor is generally the computed RMS of noise from all pixels from dark frames (usually, you would want to compute it from many dark frames, and generate an average RMS). That would include banding, but bands tend to be outliers, so they don't impact the RMS all that much. The difference between the 5D III DR (10.97 stops) and the possible 5Ds DR (maybe around 11.23 stops) could very well be the difference in banding. That isn't much of a difference, though, assuming the 5Ds does arrive with read noise and FWC similar to the 7D II.
My problem with these statements (paraphrased) is they conflict:
A. The 5Ds has the same dynamic range as the 5D III
B. The 5Ds has more editing latitude
You can't have both at the same time. Maximum editing latitude is ultimately determined by dynamic range. To speculate a bit. One thing that could be going on is that testers who are saying "more dynamic range" are feeling more freedom from lower banding. They may FEEL they have the ability to push shadows more, because the noise they see has a better characteristic. You often didn't need to push shadows at all in the past to see banding...it was often visible right there in the midtones. That would be zero stops shadow pushing, if that was the case.
Without banding, the difference between not pushing at all (rendering the image to the 8 stops of an 8-bit screen), or pushing a small amount (maybe a stop before banding stopped you)...and pushing up to the three stops allowed by ~11 stops of dynamic range, would seem quite huge. Perceptually, that would seem like a huge difference. Mathematically, things wouldn't have really changed. If, mathematically, the 5Ds really does have "the same" dynamic range as the 5D III, then logically the claims of more shadow pushing ability are more perceptual than mathematical (and, it would be unlikely that the 5Ds has over 13 stops of engineering DR.)
I don't know what the case is, but trying to reconcile the two statements A and B above, this is one of the conclusions I can draw. You either have the same dynamic range as the 5D III (or slightly better, more like the 7D II)...or you have more dynamic range. To have more dynamic range, you have to have either lower read noise or a larger FWC, or both. You can't have the same dynamic range and lower read noise at the same time...because lower read noise with the same FWC would mean you have more dynamic range.
At this point, to know any more, we need to see literal tests.
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to me this just means he's switching to pixel talk. and he's right. you do have more latitude to edit if you have more data even if the tonal depth of that data is shallower.
but whatever. parsing it further is meaningless. And I'm sure since the canon DR and shadow noise problem is as well known as iphones bending, the #1 thing every test will make sure to cover is how, if at all, they have fixed this problem. And given the difficulty of doing a proper test, I'm sure we'll have half the threads claiming it is the best DR on earth, and half of the others claiming it is worse.
Personally I'm not going to look at computational single digit tests like dxo. I'm going to watch Lloyd Chambers blog as well as a few other highly methodical reviewers. Plus the guy has a lot of experience exposing the DR woes on the 5DMKIII which still to this day many deny.
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psolberg said:
Yeah, we need actual data. Hopefully that will start appearing soon after the camera is released. I know a couple astrophotographers who may grab one of these things early, and Bill Claff has started visiting Cloudy Nights. Some people respect his numbers more than DXOs, although they generally show the same gap between Canon and others. Looking forward to him generating PDR numbers for the 5Ds.
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Marsu42 said:
I think so. Since I brought up the term "usable" initially, the amount of noise in the signal is what I considered the variable allowing the inherit DR from the sensor to be usable or not. It's been mentioned, but just to get everyone on the same page again as this wagon circles back:
Canon 5D3 (Read Noise 33.6 @ ISO 100)
http://sensorgen.info/CanonEOS-5D-Mark-III.html
Canon 7D MkII (Read noise 12.9 @ ISO 100)
http://sensorgen.info/CanonEOS-7D-Mark-II.html
So assuming the same pixel but on a FF scale, add in additional tweaks to throw out HIgh ISO, significantly reduce operating temps on sensor to further reduce noise, etc... blah blah blah.... Throw in what Rista said about maybe/IF we see the read noise drop from that 12.9 to half, around 6-7 .... Voila
Yes less noise compared to a 5D3 by quite possibly a lot, thereby perhaps, at least perceptually, allowing for a bigger shadow pull free of that nasty read noise you would other raise the middle finger to ;D
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