Luminous Landscape Forum
Equipment & Techniques => Cameras, Lenses and Shooting gear => Topic started by: thierrylegros396 on March 03, 2014, 02:05:11 pm
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OK, it's not a still camera, but results seems to be very good for a "small" sensor < Full frame.
Read the "In depth review" page.
http://www.dxomark.com/Reviews/RED-Epic-Dragon-review-First-camera-to-break-the-100-point-DxOMark-sensor-score-barrier (http://www.dxomark.com/Reviews/RED-Epic-Dragon-review-First-camera-to-break-the-100-point-DxOMark-sensor-score-barrier)
Have a Nice Day.
Thierry
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Ridiculous hype-based nonsense. Great it has more "dynamic range". Still somewhat unclear how their measurements system works, I mean don't video cameras function differently in the way that they handle digital imaging?
But anyway, put up a still from a RED next to a Nikon D800e, and then put both of those up next to a PhaseOne IQ260 and then get back to me.
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It seems that the reviewers do not have access to the raw bayer data. I don't know how they can verify the results.
Granted that a half a stop in DR doesn't seem impossible for the coming generation of sensors that /aren't in production yet/. But I also wonder if the extra DR isn't at the top end, and not at the bottom end? You can add a stop of highlight protection and still call it DR, even where little improvement has been made in terms of absolute signal handling.
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Some analysis over here:
http://www.dxomark.com/Reviews/RED-Epic-Dragon-review-First-camera-to-break-the-100-point-DxOMark-sensor-score-barrier/In-Depth-Analysis
DxO believes they are using temporal noise reduction (through multisamplng) to achieve the unexpected results they are getting.
They also note that the sensor calls for no analog gain. The specs have it as a native ISO 250, but the measured ISO is ISO 104. That's interesting.
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Why are people still getting excited about dxo mark?
These are technical points given by pixel peepers who are not photographers or artists and who have no clue about actual qualities of an image.
You can as well try to find the painter with the maximum image quality by ranking their quality like brush stroke, color range, etc.
Or ranking poetry as done by the ignorant English teacher in the movie "Dead Poets Society".
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After reading some of these (and other) negative comments about DxO I'm curious whether there is ANY merit to the data DxO produces? Can any of their measurements play a part in selecting equipment, whether lenses or cameras?
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Why are people still getting excited about dxo mark?
These are technical points given by pixel peepers who are not photographers or artists and who have no clue about actual qualities of an image.
As far as I am concerned, my confidence in the DxOMark results is increasing every time they release such results.
We had been told by Red users for months/years that they were seeing incredible DR in their files... and DxO confirms that. MFDB owners tell us that they see more noise in the shadows of the P45+ compared to a Sony A99... and DxO Mark results confirm that,... the list goes on and on.
The DxO Mark results are simply the most credible measurement we have of the technical qualities of imaging sensors today.
Now, it is totally obvious that the technical qualities of imaging sensors are only a small contributors to the quality of the images captured by the camera using this sensor (my view remains that "the camera is the least important part of photography"), and the technical qualities of an imaging sensor mesured by DxO is only one aspect of a camera system (together with UI, handling, AF, lenses,...) but if you try to select a camera based on some defined technical sensor needs, DxOMark is the best information source in town.
Cheers,
Bernard
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Why are people still getting excited about dxo mark?
Why are people still getting angry about dxo mark?
It seems to measure pretty accurately and repeatably just what it claims to measure. It does not measure artistic genious, but then it never claims to do so either, so why be upset that it does not?
-h
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Thing is Alexa users are not about to go running to the shop to buy a RED just because a bunch of measurebators says a sensor gets a 100 point score. They are a lot smarter than that.
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...measurebators...
You lost me right there. Once you have to resort to name-calling, I am assuming that you have nothing of value to add to the discussion.
-h
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my comment is valid, you only have to look around on the web to see plenty of people who like to comment on equipment they neither own/rent/use/have experience of. and use some statistical evidence that doesn't always offer any insight to real user experience (and how different those can be)
whether you attach any credence to my comment is entirely up to you, it makes no difference to me.
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my comment is valid, you only have to look around on the web to see plenty of people who like to comment on equipment they neither own/rent/use/have experience of. and use some statistical evidence that doesn't always offer any insight to real user experience (and how different those can be)
whether you attach any credence to my comment is entirely up to you, it makes no difference to me.
The fact that some people make stupid usage of data doesn't imply that this data is useless.
Besides, some photographer who do use their equipment to create art (within the limits of their abilities of course) are also interested in their technical aspects and have a scientific background that enables them to secure a certain level of understanding. What's wrong with that?
Cheers,
Bernard
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This discussion seems to be generating more heat than light.
As someone who takes his photographs in the real world, rather than in a laboratory, I am nevertheless interested in the technology and I can make my own decsions about whether lab results have, or have not, any significance for my practice.
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What Red has done is commendable. I hope that 35mm still cameras also come in "modular" format like MF backs (of course at a much lower price)
As far as DXO ratings go, it is excellent as a comparison tool, especially for lenses. If I want to know which lense is sharper or has less CA or has less distortion, DXO results are enough.
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I hope that 35mm still cameras also come in "modular" format like MF backs (of course at a much lower price)
With cameras as Sony's and adapters, we essentially have this already. It will get cheaper in the future and better as adapters improve too.
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The fact that some people make stupid usage of data doesn't imply that this data is useless.
Besides, some photographer who do use their equipment to create art (within the limits of their abilities of course) are also interested in their technical aspects and have a scientific background that enables them to secure a certain level of understanding. What's wrong with that?
Cheers,
Bernard
nothing wrong with that at all. i was merely commenting on how this sensor will now be hailed as the imaging fidelity zeitgeist that many will compare/mention yet never buy or use.
no idea if it was just a U.K. thing but there was a card game called Top-Trumps when i was a kid, the highest scoring card was the lambo countach, if you had this 100 point card you were king of the playground, web chatter will hail the RED as the new King but in the real world people will carry on making images with what they have.
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Hopefully we can retire the term "measurebator." It's anti-intellectual.
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Some analysis over here:
http://www.dxomark.com/Reviews/RED-Epic-Dragon-review-First-camera-to-break-the-100-point-DxOMark-sensor-score-barrier/In-Depth-Analysis
DxO believes they are using temporal noise reduction (through multisamplng) to achieve the unexpected results they are getting.
That seems very likely, since DXO has to work with 5:1 compressed output from a 24fps video stream that has then been processed by RED's proprietary software, not a single raw frame. And of true, this completely invalidates any scoring comparisons to other cameras of DR and color depth -- unless those other cameras are also evaluated on the basis of files created by the blending of multiple frames.
That, along with the fact that this critical qualification is buried, deep, deep into the article rather than mentioned up front or through the multiple pages of open-mouthed wonder, makes the whole story smell like link bait.
The specs have it as a native ISO 250, but the measured ISO is ISO 104.
It is totally expected that the default exposure index [250] is higher than the lower extreme of the ISO's speed latitude range [104]. Note that what DXO persistently yet falsely misdescribes as the "measured ISO speed" is in fact what the ISO describes as the lower extreme of the ISO speed latitude range, based on being the lowest exposure index at which the camera still gives a barely acceptable three stops between metered mid-tones and blown highlights. "Minimum", not "ideal" or "recommended" or "required" or "any deviation is a misstatement of ISO by the camera maker".
For a video camera giving about 14 stops of DR, and where lighting can fluctuate during a take, placing the midtones at a minimal three stops below blown highlights and so about eleven stops above the shadow noise floor would be crazy, so of course RED (along with all sensible designers of high-end still cameras) choose a different placement of about "4 stops above, 10 below" which better protects highlights while still keeping the noise floor at a negligible level in most situations.
P. S. Dead-horse flogging time: What the ISO 12232 standard actual says about ISO speed and other measures, and the clear contradiction to what DXO says, is summarized in my post at http://www.luminous-landscape.com/forum/index.php?topic=87439.msg711760#msg711760
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As far as I am concerned, my confidence in the DxOMark results is increasing every time they release such results.
We had been told by Red users for months/years that they were seeing incredible DR in their files... and DxO confirms that.
That much is plausible ... once one acknowledges that the DR has probably been enhanced by the averaging of information from several frames taken in rapid succession (temporal noise reduction), sort of like HDR on the fly. Since other video output can get similar processing, this is reasonably fair for comparisons to video produced with other tools -- just not for comparing to images produced using a single frame from a still camera.
I am even willing to speak up in favor of doing some assessments of the final images that a camera and associated software [in-camera or in-computer] can deliver, though I understand why some people are also interested in assessing raw ADC outpu, which is not available in this case.
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my comment is valid
"Measurebator" hints that you see other people as standing behind their oscilloscope with their fly open. People tend to not like being characterized that way.
"putting too much weight on measurements rather than experience" would seem to be a neutral (though awkward) way of expressing what you wanted to say.
-h
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That's your interpretation not mine.
As I said above i was commenting on the nature of web chatter about stuff they know little about and are never likely to have in their hands,
'it scores 100 on Dxo so it's the best camera in the world and your camera sucks'
The guys in lab coats are just supplying the measurebators ammunition (and more importantly some data for those who know how to look beyond a perfect 100 score)
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Hopefully we can retire the term "measurebator." It's anti-intellectual.
Since when? I seem to recall many people on this forum and around the web using the term. It's no more ridiculous than the term "tweet." Look it up and get with the program. Welcome to the internet son.
Also what MrSmith says is correct. His comment is the most valid on this entire thread.
RED makes some neat products, but the Arri Alexa will remain the gold standard. Look at ALL NINE of the Academy Award Nominated films for Best Picture. NONE OF THEM... let me repeat that.... NONE OF THEM used a RED camera. Many of them used Arri film or digital cameras.
No Dragon, no Epic, no Scarlet, no nothing.
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Since when? I seem to recall many people on this forum and around the web using the term. It's no more ridiculous than the term "tweet." Look it up and get with the program. Welcome to the internet son.
The word "measurebator" is made up of which two English words? The implication being? I thought so. The word "tweet" compares ... how?
We're going to kill this meme off, but good.
I remember when people -- everyone -- used the N word -- every day all the time -- to refer to blacks. I looked that one up and refused to get with the "program."
And I'm not your "son", unless you and "mom" want to help me out with a new car.
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That much is plausible ... once one acknowledges that the DR has probably been enhanced by the averaging of information from several frames taken in rapid succession (temporal noise reduction), sort of like HDR on the fly. snip
I don´t think this is based on frame averaging. DSMC cameras have a HDR mode to do this and this way reach for at lot more DR than shown here.
That said, a RED won´t become my daily stills camera for a couple of reasons but we already used it in parallel with a MDB for a portrait and decided to go with the R3Ds for the final output, go figure. There has been a comparison among cameras of member CB, and that was only the "MX". I don´t like the Red fanboy hype at all and I would never think of just pulling a frame from motion work but if you set up your workflow for a still you might use a motion camera and end up with a good result (and awful motion).
I couldn´t care less who won the best picture awards for what reasons, RED is a very young company and they stirred up some dust in this traditional business.
Cheers,
Ulf
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Welcome to the internet son.
Being rude on the internet may be common. This does not mean that it should be applauded.
-h
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I don´t think this is based on frame averaging. DSMC cameras have a HDR mode to do this and this way reach for at lot more DR than shown here.
Temporal averaging of consecutive frames is not the same as the usual HDR; it takes several consecutive frames all at the same exposure level and averages them, rather than the usual HDR approach of using frames at very different exposure levels. So it will not produce the big DR expansion of HDR, but it will reduce the noise floor, particularly when using in a stationary test subject so that all frames see exactly the same light at each photosite. Roughly, if several frames are averaged with equal weight (not that this is exactly what RED does), the level of random uncorrelated noise will go down and the SNR and DR go up by the square root of the number of frames averaged, so if two consecutive frames are averaged, the improvement is half a stop, four frames improves by one stop, and so on. Color depth will improve in the same way.
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Ok, I understand the technique (behaves like having more transistors in parallel of an input stage of an amp) what I don´t understand is where they assume multiple frames come from. Actually RED announced an ADD tech for pulling stills of a higher quality with their new release of RedCineX and Dragon files, which may take advantage of this method, they also have a new OLPF now, which both were not involved in this test as far as I can see. Are you talking about multiple readouts during the selected "shutter" speed? Anyway, used to MFDB the DR of a Red camera (even MX) is impressive. Obviously the rest is comparing apples and oranges ;-)
Cheers,
Ulf
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Ok, I understand the technique (behaves like having more transistors in parallel of an input stage of an amp) what I don´t understand is where they assume multiple frames come from.
I see good evidence for temporal averaging in the DXO data (as do the folks as DXO):
1. The total SNR graphs go up to about 50dB (at minimum ISO exposure index, 100% illumination). With just photon shot noise, that requires counting at least 100,000 photons (the photon count needed to achieve a given SNR in dB, SNRdB, is 10^(SNRdB/10).)
That is about 4000 photon counts per square micron of photosite area, more than twice what is typical and almost three times what I see measured for the D800 which has similar photosite size.
That can only be achieved by some combination of (a) deeper wells, to actually count 4000 photo-electrons per square micron, and (b) combining the photo-electron counts from several frames (temporal averaging).
2. The base ISO speed Ssat (what DXO calls "ISO") is 104, comparable to and indeed a bit higher than cameras like the D800 [Ssat=75 for the D800].
3. If there were no temporal averaging, having over double the well depth of the D800 and also this higher Ssat would require almost tripling the quantum efficiency. (Doubling well depth at equal QE would half the base ISO speed Ssat.)
4. Sensors like that of the D800 are close to the maximum possible QE for a Bayer CFA sensor, and triple the QE of the D800 would be beyond 100%: it seems impossible that RED could have increased the QE of its Bayer CFA sensors by nearly enough to explain the DXO measurements.
By process of elimination, temporal averaging seems almost certain.
Arguably, this still gives a legitimate advantage for exposures when light is abundant: effectively, the light used to form each frame is being gathered over a longer time than sensor saturation normally allows, so it is almost equivalent to increasing the well depth and decreasing the base ISO speed Ssat by a factor of more than two -- and yet doing this with only about 1/24s between frames using RED's fast rolling shutter, and so handling subject and camera motion better than frame averaging with a normal still camera, which would need to have more time between the frames.
So a stills photographer might get some advantage when longish total exposure times are acceptable, in exchange for paying about twenty times as much as for a stills cameras with the same sensor size.
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By process of elimination, temporal averaging seems almost certain.
Indeed, and it satisfies Occam's Razor.
Cheers,
Bart
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I suspect that they are doing temporal averaging, but not of equal length exposures.
I suspect they are taking the second shot at a much faster shutter speed. In doing so, they can fit two exposures into a what the users expects would be the space for one (e.g., 1/60th plus 1/250 or so all in the space of 1/50th). And the clear win on dynamic range is at the top end, with some improvement in the midtone response.
Highlight protection is what a cinema shooter wants here I think.
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I suspect that they are doing temporal averaging, but not of equal length exposures.
I suspect they are taking the second shot at a much faster shutter speed.
Since it is from a video feed, I guess a weighted rolling average of "equal" frames: each frame gets the same exposure, and the processed output at each time stamp is something like:
1/4 the previous frame + 1/2 the current frame + 1/4 the next frame.
But maybe someone who actually knows something about how temporal averaging is typically used in video processing could correct my guesswork?
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Since it is from a video feed, I guess a weighted rolling average of "equal" frames: each frame gets the same exposure, and the processed output at each time stamp is something like:
1/4 the previous frame + 1/2 the current frame + 1/4 the next frame.
But maybe someone who actually knows something about how temporal averaging is typically used in video processing could correct my guesswork?
Hmm, hadn't thought of that. That's interesting.
But it seems there'd be a lot of detail lost on moving subjects. I wonder if this is good enough for cine? If you do one long and one very short exposure, you can use the very short exposure as a basis for detail enhancement. And you get the extra stops of headroom at the top end, and clean. Enhancing midtone response is a nice dividend.
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BJL,
Thank you for your in-depth explanation. I have to admit I also like the artistic side of our job.
;)
Cheers,
Ulf
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Hmm, hadn't thought of that. That's interesting.
But it seems there'd be a lot of detail lost on moving subjects. I wonder if this is good enough for cine? If you do one long and one very short exposure, you can use the very short exposure as a basis for detail enhancement. And you get the extra stops of headroom at the top end, and clean. Enhancing midtone response is a nice dividend.
Hi Luke,
The problem though, besides complexity, is that equal exposures lead to lower average shot noise. It's also easier to average (1 bit shift per 2 exposures). Also, it's easy enough to store the cumulative result of multiple exposures and discard read noise at the same time, even within 16-bits (4x 14-bits <= 16-bits).
Cheers,
Bart
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Hi Luke,
The problem though, besides complexity, is that equal exposures lead to lower average shot noise. It's also easier to average (1 bit shift per 2 exposures). Also, it's easy enough to store the cumulative result of multiple exposures and discard read noise at the same time, even within 16-bits (4x 14-bits <= 16-bits).
There's a good line of reasoning in it, and I don't discount it. But I was also thinking that with two exposures, one two stops faster in shutter speed, you'd get both the extra highlight headroom, and almost all of the benefits of averaging (after normalizing) everywhere but in the lowest 2-3 stops.
I was thinking that the benefits of highlight headroom and added midtone response would be most desirable to a cinematographer, and that the shadow response would be secondary. After all, there are some natural noise reduction effects in rapid presentation of sequential images. People do not perceive shot noise going by at 30 frames per second so readily.
Then I was thinking of the benefits of detail enhancement, which could be varied. I was comparing this to the inevitable smearing that would happen borrowing from adjacent frames, which seems like a compromise best suited for broadcast and streaming applications.
Having said all that, you might be right. Temporal noise reduction could be strictly an interframe function, and that might be all that's going on. But that would be a little disappointing. And a little disappointing of DxO to classify this in the same category as single-shot cameras. If Nikon were to introduce, in firmware, a two-shot burst mode with in-camera averaging, could they too take the lead back in the sensor rankings?
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snip If you do one long and one very short exposure, you can use the very short exposure as a basis for detail enhancement. And you get the extra stops of headroom at the top end, and clean. Enhancing midtone response is a nice dividend.
[/quote]
Luke,
That´s exactly what RED does in HDR mode. You just select "HDR" and dial in the number of stops of extra highlight protection. The camera than records two video tracks simultaneously which can be blended in RedCineX in various ways. Downside is the doubled amount of data, the need of higher compression and with fast moving objects different blur and timing caused by two exposures and different shutter speeds. Great onboard feature though.
Cheers,
Ulf
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... If you do one long and one very short exposure, you can use the very short exposure as a basis for detail enhancement.
That´s exactly what RED does in HDR mode. You just select "HDR" and dial in the number of stops of extra highlight protection.
Indeed, that is how RED's HRDx mode works, but DXO did not that special mode for its test, so all frames in the video stream fem which the stills were derived are at equal exposure. In this normal mode, the 24fps output is produced from 24fps capture, so no "two frames captured per each frame output". That is why a rolling average is the only way I can see it operating in the mode use for the DXO testing.
To answer a question that someone (Bernard?) asked; I would think that a digital still camera could add a similar "DR enhancement" mode, but it would require either
1) the camera held dead steady, on a tripod
or
2) a very short lag between the frames, which would probably require a video mode that outputs full resolution, with no sub-sampling or binning done on the sensor chip.
Video-stills hybrid models like the Panasonic GH4 might have the latter hardware capability.
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I have been a publishing poet and writer and a serious photographer for forty years.
All the information one can get abut ones art is good.
An artist is a person on whom no information is lost.
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Few will care about numbers. It might help if DxO bothered to tell you how they test and what exactly they are testing.
Based on my own personal use of quite a few cameras I consider DxO to be largely irrelevant and in some cases I've had serious doubts about their methods and scores.
The lens reviews are just as vague (perceived mp ratings for lenses)
There may be some value in some of their results, but they've gone about it the wrong way and are unconvincing and pretty much pointless to "people who actually take photos rather than measure things"