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How to expose correctly if D-Log is fixed to ISO500 !!??
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DrMrdalj
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For any Log gama to work correctly picture HAS TO BE EXPOSED CORRECTLY. While you can make picture darker by using ND filters, you can not make it brighter - therefore ALL CAMERAS that I ever used (Sony A7, FS5, FS7, Panasonic GH4 and GH5, all Canons etc) have ISO RANGE in Log profile FROM NATIVE ISO of camera UP TO ANY HIGHER ISO. If we look at GH5 as example, as it has same sensor as X5S, it's V-Log L range is ISO400-ISO6400 (while in regular non-log picture profiles you can set down to ISO200)...
Camera native ISO is one with best dynamic range and least noise - according to all graphs at DJI website for X5S it is ISO100 (sam as for X5)
IMG_7916.PNG

WHY anyone at DJI thought that would be wise to set D-Log at FIXED ISO500 (as they did in latest I2 firmware)!!?? Is there any official explanation?
Is there any way to shoot ProRes in D-Log at ISO640, 800, 1000 or 1600!?

I remind you that for any log gamma to work correctly picture has to be exposed correctly - underexposed image suffer greatly in log, therefore slight overexposure or Expose-to-the-right is preferred.
As I2 is aerial platform for scenes that can not be lit by artificial light - how can I achieve slight overexposure with fixed ISO!??

Any ideas how to expose correctly or official DJI comments?
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raven4
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I'd be interested in DJI's response, too. My knee jerk response is to think that, by nature, Log gammas increase the dynamic range to such an extent that it becomes more like shooting with film. That is, the increased dynamic range makes shooting log open to a pretty wide range of exposure values, which are then recovered in post. Remember the pull and push processing that can be done with film?I think the DR of the X5S is something like 12.5 stops, really not wide enough to fix the ISO at 500. Having said that, if one uses EV values to over or under expose up to +2EV or -2EV, thats the equivalent of having ISO values of 125(-2EV), 250(-1EV), 500(0EV), 1000(+1EV) and 2000(+2EV). Then post process for the push or pull.
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DrMrdalj
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raven4 Posted at 2017-3-3 05:31
I'd be interested in DJI's response, too. My knee jerk response is to think that, by nature, Log gammas increase the dynamic range to such an extent that it becomes more like shooting with film. That is, the increased dynamic range makes shooting log open to a pretty wide range of exposure values, which are then recovered in post. Remember the pull and push processing that can be done with film?I think the DR of the X5S is something like 12.5 stops, really not wide enough to fix the ISO at 500. Having said that, if one uses EV values to over or under expose up to +2EV or -2EV, thats the equivalent of having ISO values of 125(-2EV), 250(-1EV), 500(0EV), 1000(+1EV) and 2000(+2EV). Then post process for the push or pull.

Please note that you can not use EV values for exposure - exposure consists of shutter speed, aperture and ISO sensitivity - EV value is just there to tell you how much over or under exposed picture is comapred to camera automatic metering sugestion. EV0 is there when you exposed exactly according to camera automatic aversge exposure metering, what is not what you want in Log.
Regarding the Log gama - it is invented to record more then 7 stops of dynamic range what is maximum in Rec709, bit even with Log gama you are not suposed to significantly correct exposure in post. Darker regions of picture even in Log hold less information then brighter ones, so you are expected to have proper exposure directly while filming, or even to ETTR.
These are just basic of using cinema camera.
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raven4
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DrMrdalj Posted at 2017-3-3 08:57
Please note that you can not use EV values for exposure - exposure consists of shutter speed, aperture and ISO sensitivity - EV value is just there to tell you how much over or under exposed picture is comapred to camera automatic metering sugestion. EV0 is there when you exposed exactly according to camera automatic aversge exposure metering, what is not what you want in Log.
Regarding the Log gama - it is invented to record more then 7 stops of dynamic range what is maximum in Rec709, bit even with Log gama you are not suposed to significantly correct exposure in post. Darker regions of picture even in Log hold less information then brighter ones, so you are expected to have proper exposure directly while filming, or even to ETTR.
These are just basic of using cinema camera.

you've missed my point, sir. EV is used to define the level of over/under exposure. An EV of +1 is equivalent to 1 stop over exposure. Therefore, rather than adjust ISO (AKA gain) you over or under-expose, then process according to the push or pull in post. The wide DR of log exposure (12.5 stops) gives you film like processing capability by over/under exposing without losing hilite/shadows. Given that REC709 is 7 stops, you have 4.5 stops of exposure latitude to play with for a flat lit scene. Comprende? If you ever shot with celluloid film, you would understand the process of pushing or pulling exposure according to EV.


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raven4 Posted at 2017-3-3 12:40
you've missed my point, sir. EV is used to define the level of over/under exposure. An EV of +1 is equivalent to 1 stop over exposure. Therefore, rather than adjust ISO (AKA gain) you over or under-expose, then process according to the push or pull in post. The wide DR of log exposure (12.5 stops) gives you film like processing capability by over/under exposing without losing hilite/shadows. Given that REC709 is 7 stops, you have 4.5 stops of exposure latitude to play with for a flat lit scene. Comprende? If you ever shot with celluloid film, you would understand the process of pushing or pulling exposure according to EV.

I understand what you are talking about but, whig due respect, I believe that you are not familiar with Log workflow and post - Log is not RAW, and you are not supposed to push/pull picture in post by whole 2 stops. Please do the research on Log exposure and workflow, and you will learn that proper exposure while shooting (exact, correct exposure) is of outmost importance for Log to work correctly. Underexposed images are big no-no in Log workflow, as Log is not linear and shadows are much more luma compressed then highlights , so in Log you can do highlights recovery but shadows recovery is almost useless... Even more if you consider details in the picture such as textures... Therefore you will learn to shoot Log overexposed by 2 stops, or use ETTR technique. Please note once more that Log is not linear, Log is not RAW, Log is not free of shadows push/pull artifacts, it can't be brought up by 2 or 3 stops in post without obvious degradation,  so therefore it has to be exposed correctly while shooting. Please familiarize with professional Log workflow before making any conclusions.
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DrMrdalj
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raven4 Posted at 2017-3-3 12:40
you've missed my point, sir. EV is used to define the level of over/under exposure. An EV of +1 is equivalent to 1 stop over exposure. Therefore, rather than adjust ISO (AKA gain) you over or under-expose, then process according to the push or pull in post. The wide DR of log exposure (12.5 stops) gives you film like processing capability by over/under exposing without losing hilite/shadows. Given that REC709 is 7 stops, you have 4.5 stops of exposure latitude to play with for a flat lit scene. Comprende? If you ever shot with celluloid film, you would understand the process of pushing or pulling exposure according to EV.

One more important  thing: if DJI graphs are correct there is just 10.5 stops of dynamic reange at ISO500 - why do we waste 2 more stops of gennuine dynamic range, as they can not be brought back in post? Why do we shoot with lower SNR if there is better SNR at ISO100?
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DrMrdalj Posted at 2017-3-3 17:34
One more important  thing: if DJI graphs are correct there is just 10.5 stops of dynamic reange at ISO500 - why do we waste 2 more stops of gennuine dynamic range, as they can not be brought back in post? Why do we shoot with lower SNR if there is better SNR at ISO100?

Would really like DJI to come forward with some reasoning of why we are locked at ISO 500 using D-log in the new firmware. I will not update my I2 until I understand and agree with the reasoning for locking us at one set iso. Or, they revert that feature.
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raven4
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Gybo102 Posted at 2017-3-3 19:29
Would really like DJI to come forward with some reasoning of why we are locked at ISO 500 using D-log in the new firmware. I will not update my I2 until I understand and agree with the reasoning for locking us at one set iso. Or, they revert that feature.

FWIW, Sony, Red, Panasonic and Arri all lock the ISO at a single value when shooting log formats. RAW or otherwise, ETTR is the recognized technique for exposing Log footage. It's correct that one does not want to underexpose log footage because of noise issues, however. +2 stops of overexposure works quite well when the DR is 14 stops. Admittedly 2 stops is too much when the DR is 10.5 stops.I was speaking generically; and with several years of experience shooting Sony F55 cameras. So, you are free to do as you wish DrMrdalj. My workflow has worked, successfully, for many years. Your attitude is parochial, insulting and dogmatic. All the best to you.
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raven4 Posted at 2017-3-3 19:38
FWIW, Sony, Red, Panasonic and Arri all lock the ISO at a single value when shooting log formats. RAW or otherwise, ETTR is the recognized technique for exposing Log footage. It's correct that one does not want to underexpose log footage because of noise issues, however. +2 stops of overexposure works quite well when the DR is 14 stops. Admittedly 2 stops is too much when the DR is 10.5 stops.I was speaking generically; and with several years of experience shooting Sony F55 cameras. So, you are free to do as you wish DrMrdalj. My workflow has worked, successfully, for many years. Your attitude is parochial, insulting and dogmatic. All the best to you.

Fellas... im not trying to get in the middle of ur "discussion" I just would like a rep from DJI to explain the decision behind locking us at iso 500. Personally, I dont feel it should be locked. Tell me the benefits.. explain why its better... (if it is) but dont tell me its the ONLY iso I can use... it can be limiting. like in the original post.. the info they provided does not show that ISO 500 is "Ideal" if you care about dynamic range and noise..

DJI, please come forward, we would like some info. Thank you.
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To explain the native ISO of DLOG, let's start with exposure.

1. Exposure

In the imaging engineering point of view, a good exposure is to make the imaging of a 18% gray in the YCbCr domain to be  0.43~0.5 of the white level. So it's very important that the good exposure is measured after gamma, not linear.

2. Gamma

The cameras for photography traditionally use a standard gamma (e.g., Rec709) to compress the pixel to 8bit for digitalizing. So the good exposure means the linear image after a Rec709 gamma, 18% gray will be exposed to 110~128 if the white level is 255. However, as the sensor technology is evolving fast, the dynamic range of a morden sensor is far ahead of standadizing Rec709.

DR=20log10(FWC/Noise), FWC means the maximum capacity of the electrons, and noise means the noise level of dark.

A typical SONY APS-C sensor will have 84dB+ (14 fstops+) dynamic range. The goal of a gamma and exposure is to preserve as large information of the scene as possible, regarding both highlight and darkside. Whether to preserve the highlight or darkside is up to the photographer's tone. Things over-expsoured is forever gone and darkside with noise has chance to recover by strong image processing algorithms. Therefore, the camera vendors make a good balance between the highlight and darkside, by choosing a proper gamma curve, according to their capability of chip and characteristics of sensor.

3. LOG gamma

The cinematography is different from the photography. Cinema camera shoots RAW with 12/14/16 bits, and the footage is generated mostly by post processing software, which is far more powerful than the camera. So given the dynamic range, the highlight preserving is the first priority. Simply speaking, the camera will shoot a under-exposed image and store all the effective bits of the darkside thanks to the RAW, and recover the dark by strong post processing.

Here is a post to introduce the comparison between LOG gamma and standard gamma.
https://prolost.com/blog/2005/5/15/log-is-the-new-lin.html

If the LOG gamma is regarded as a kind of digital gain, the cinema camera tends to use the digital gain first. It breaks the rule of analog gain first. Actually the darkside will have dozens of dB amplified when using LOG gamma. Thanks to the strong signal processing algorithms in the post processing software, the darkside is still useable.

4. Native ISO

Usually, when applying the analog gain 1x and LOG gamma, we say the equivlent ISO is called native ISO.

After applying the DLOG which has been well tuned to match 12.8 fstops, the 18% gray is 2.3 fstops above the normal gamma. Do you remember the exposure is mostly responsible for the 18% gray? Therefore, the exposure should be reduced 2.3ev in order to match the aperture/shutter of other cameras. In our case,

native ISO = Baseline ISO + 2.3ev = ISO500.

That means use the same aperture/shutter/iso, we will make the brightness of 18% gray be aligned with any cameras, no matter for photo or for cinema.

5. More-over

The question is if we can enable 2x/4x/... analog gain? I have to say it's depending on the FPN (fixed pattern noise) of the sensor. Some vendors lock the ISO of LOG while others provide limited but selectable ISOs.

DJI R&D team is testing 2x/4x analog gains with the representative customers. The footage should be projected to a large sceen, under a very strict inspection, to ensure the affordable artifects. So please be kindly patient and we might enable more ISOs in the future.

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Two things - it's not true that Alexa and Red camera fix their ISO when shooting log. Many Sony cameras do this however.

Secondly, all sensors have a native sensitivity. By changing the ISO on a digital camera you're not in any way affecting how sensitive the sensor is to light.

What you're doing is telling the camera to put a curve on the image to push or pull it.

Many cameras do this in very sophisticated ways - the Alexa, for example, effectively has internal LUTs hidden from the user for every combination of white balance and ISO setting - that way the clever folk there can get the best out of the image.

There's an argument to be said that it's better to have the option to apply such a curve before a lossy recording format like ProRes is applied - that's why Arri let you do it.

Others like Sony take the engineering approach that a fixed ISO for log footage is a safer way to get the best image quality as it forces you to adjust the light hitting the sensor in other ways - aperture, NDs, etc. They often default to 1600 or even 3200 in log - this helps protect highlights as you have to use a lot of ND, etc, to get a correct exposure.

But there's no reason you can't pull up an image in post by a couple of stops - in formats like ProRes 4444 and certainly raw on the Inspire you aren't going to be generating a whole lot more noise than if the Inspire let you do it in camera.
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edmoore Posted at 2017-3-4 02:39
Two things - it's not true that Alexa and Red camera fix their ISO when shooting log. Many Sony cameras do this however.

Secondly, all sensors have a native sensitivity. By changing the ISO on a digital camera you're not in any way affecting how sensitive the sensor is to light.

Thanx, very much, to edmoore and DJI-CAO for good explanations. Right on. The only thing I would add is in reference to DJI-CAO's comment about RAW. RAW data does not use a gamma curve. The gamma curve is applied when RAW data is debayered into REC709. The RAW info is recorded linearly, which is why there's exponentially more data stored in the shadows than in the hilites. It's up to the mathematical regression of the linear RAW data to be converted to REC709, REC2020, whatever color space.
edmoore wrote: "But there's no reason you can't pull up an image in post by a couple of stops - in formats like ProRes 4444 and certainly raw on the Inspire you aren't going to be generating a whole lot more noise than if the Inspire let you do it in camera."


Altho', I'll concede that 2 stops is a bit much for this sensor. I routinely overexpose 1.5 stops on my F55....ETTR, but don't blow out those hilites. The problem with a single channel histogram is that you can blow out one color channel and never know it. That's why I would hope DJI consider an RGB Parade option on the display. Once hilites are blown, they're gone forever. That's why judicious use of the histogram is so nice to have one on the app.

Great info, thanx again, guys.

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DJI-CAO Posted at 2017-3-3 22:28
To explain the native ISO of DLOG, let's start with exposure.

1. Exposure

CAO- Thanks for the explanation. And I think it adequately answers what some on this forum have asked. However, many DP's shooting log gammas from sony, canon et. al make it a habit of shooting at 1/2 the the "native" ISO to control noise. There are many situations where the maximum DR of a log gamma isn't necessary, and the the photographer may choose to shoot at a lower ISO to control noise. Canon, with their C300markII states the native ISO at 800 whereas the baseline ISO is 100. After much complaining about the noise levels at ISO 800, Canon actually took the step of having their lead engineer state that shooting at 400 or below might be a good way to control noise in Canon C-Log2.(which many of us were already doing).  This approach is preferred to "Locking" the ISO. Simply "tell" us that the native ISO is 500 for D-Log, and then let us as photographers decide whether we want extended highlights (ISO 500) or lower noise (ISO 200 or 100) or increased "sensitivity" with higher noise (>ISO500) by lowering or raising the camera's ISO from the native ISO ourselves.
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Barry Goyette Posted at 2017-3-4 08:58
CAO- Thanks for the explanation. And I think it adequately answers what some on this forum have asked. However, many DP's shooting log gammas from sony, canon et. al make it a habit of shooting at 1/2 the the "native" ISO to control noise. There are many situations where the maximum DR of a log gamma isn't necessary, and the the photographer may choose to shoot at a lower ISO to control noise. Canon, with their C300markII states the native ISO at 800 whereas the baseline ISO is 100. After much complaining about the noise levels at ISO 800, Canon actually took the step of having their lead engineer state that shooting at 400 or below might be a good way to control noise in Canon C-Log2.(which many of us were already doing).  This approach is preferred to "Locking" the ISO. Simply "tell" us that the native ISO is 500 for D-Log, and then let us as photographers decide whether we want extended highlights (ISO 500) or lower noise (ISO 200 or 100) or increased "sensitivity" with higher noise (>ISO500) by lowering or raising the camera's ISO from the native ISO ourselves.

The method used on the Sony Professional cameras is to artificially adjust the EV so that the "light meter" tells you to open the aperture. It, certainly, doesn't effect the "gain" of the sensor, it's just is an artificial method of adjusting the meter reference so the shooter opens the f/stop or reduces the shutter speed by a number of stops to "indicate" the right exposure. That's why my OP referenced EV's...not gain. It's just as simple, in the case of the X5s, to expose, for example, according to the Go4 App to +1ev for 1 stop of overexposure, de riguer.edit: just noticed that when Dlog is selected, the ability to preset an ev is disabled. So, in Dlog mode, you can't intentionally overexpose unless you use manual exposure settings.
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raven4 Posted at 2017-3-4 10:05
The method used on the Sony Professional cameras is to artificially adjust the EV so that the "light meter" tells you to open the aperture. It, certainly, doesn't effect the "gain" of the sensor, it's just is an artificial method of adjusting the meter reference so the shooter opens the f/stop or reduces the shutter speed by a number of stops to "indicate" the right exposure. That's why my OP referenced EV's...not gain. It's just as simple, in the case of the X5s, to expose, for example, according to the Go4 App to +1ev for 1 stop of overexposure, de riguer.

Correct me if I'm not getting it, but, it sounds like you're assuming a high level of ISO invariance (i.e., assuming noise from gain is equivalent to noise from pushing the image in post) with the X5s, which I don't think has been demonstrated (I'm not, bTW, assuming the opposite). I'd argue that I'd prefer to always have control over ISO versus applying  EV adjustments (over and underexposing and subsequent adjustments in post). At the bare minimum, it appears that you're arguing that there is simply no difference (again, assuming perfect ISO invariance). If that's true, then there's really no reason to disallow the photographer the choice of achieving the result using correct exposure for a given ISO, or by the method you describe, as they arrive at the same result, and there's assumed to be no penalty for either.

In reality, camera manufacturers do tweak the image in various ways when applying gain. For instance, with the C300 mark II, it is almost always better to shoot to the right with a higher ISO, than to underexpose (and push in post) with a lower ISO, as canon is applying some gain prior to debayer at the higher ISOs. We don't know a hell of a lot about how DJI processes the image from the X5s. My experience with D-log is that it is pretty messy in the lower end even at ISO 100. I can't really imagine this scheme of locking ISO at 500 is going to improve that situation.
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Barry Goyette Posted at 2017-3-4 18:51
Correct me if I'm not getting it, but, it sounds like you're assuming a high level of ISO invariance (i.e., assuming noise from gain is equivalent to noise from pushing the image in post) with the X5s, which I don't think has been demonstrated (I'm not, bTW, assuming the opposite). I'd argue that I'd prefer to always have control over ISO versus applying  EV adjustments (over and underexposing and subsequent adjustments in post). At the bare minimum, it appears that you're arguing that there is simply no difference (again, assuming perfect ISO invariance). If that's true, then there's really no reason to disallow the photographer the choice of achieving the result using correct exposure for a given ISO, or by the method you describe, as they arrive at the same result, and there's assumed to be no penalty for either.

In reality, camera manufacturers do tweak the image in various ways when applying gain. For instance, with the C300 mark II, it is almost always better to shoot to the right with a higher ISO, than to underexpose (and push in post) with a lower ISO, as canon is applying some gain prior to debayer at the higher ISOs. We don't know a hell of a lot about how DJI processes the image from the X5s. My experience with D-log is that it is pretty messy in the lower end even at ISO 100. I can't really imagine this scheme of locking ISO at 500 is going to improve that situation.

I have written down something which other camera vendors never publish.
ISO is a legacy term from the film age. In digital time, ISO is an equivelant value used to compensate the iris and shutter, in order to be align to legacy exposure system.

Particularly, in digital imaging, ISO is related to gamma. So the sensor gain used in exposure is different when gamma changes.

So noise is not equal to high ISO
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raven4 Posted at 2017-3-4 05:04
Thanx, very much, to edmoore and DJI-CAO for good explanations. Right on. The only thing I would add is in reference to DJI-CAO's comment about RAW. RAW data does not use a gamma curve. The gamma curve is applied when RAW data is debayered into REC709. The RAW info is recorded linearly, which is why there's exponentially more data stored in the shadows than in the hilites. It's up to the mathematical regression of the linear RAW data to be converted to REC709, REC2020, whatever color space.
edmoore wrote: "But there's no reason you can't pull up an image in post by a couple of stops - in formats like ProRes 4444 and certainly raw on the Inspire you aren't going to be generating a whole lot more noise than if the Inspire let you do it in camera."

DJI have already implemented an RGB Parade option on the display and can be selected on the new firmware under camera control
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raven4 Posted at 2017-3-4 05:04
Thanx, very much, to edmoore and DJI-CAO for good explanations. Right on. The only thing I would add is in reference to DJI-CAO's comment about RAW. RAW data does not use a gamma curve. The gamma curve is applied when RAW data is debayered into REC709. The RAW info is recorded linearly, which is why there's exponentially more data stored in the shadows than in the hilites. It's up to the mathematical regression of the linear RAW data to be converted to REC709, REC2020, whatever color space.
edmoore wrote: "But there's no reason you can't pull up an image in post by a couple of stops - in formats like ProRes 4444 and certainly raw on the Inspire you aren't going to be generating a whole lot more noise than if the Inspire let you do it in camera."

Sorry for being so ignorant but I don't come from a film but videography background... So, what you are suggesting is to expose the DJI Log shots by backing off by a stop or so (EV -1 or -2) at their 500 ISO preset) value ... underexposing just a bit to preserve highlights to ensure the RGB values remain intact, correct? I always thought I had to preserve hightlihgts, but this discussion suggests the opposite, that the noise in the dark is more of an issue than blowing out the shot in the highlight regions when shooting LOG. However, are we also saying that these settings (D_Log, Cine-D) are simply LUTS applied to what we see in our preview (on the LCD) and that the non-logarithmic nature of RAW trumps DJI's LOG format so that we really need to preserve highlights more than we might otherwise with a camera with a wider effective Dynamic Range .
Another question, the Zenumuse X5 shoots an image with about 10.5 stops of DR vs. the X5S with 12.8  stops, is this correct? Thanks...
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ISO and ev  are not the same thing. However, ISO and GAIN are the same. The analogy can be made to film. On a film camera, the more sensitive the film emulsion is to light, the higher the rated ISO. On a digital sensor, the higher the bias voltage(GAIN), the more sensitive the sensor is to light. In both cases, the price you pay for boosting the gain or having more light sensitivity, the more grain or noise you'll get. High speed film is also grainy.

Likewise, with film, if you take a film stock(which is a fixed ASA or ISO) and intentionally underexpose it, then in processing the film, you can overdevelop the film to recover the image. With digital, the same thing can be done. You can underexpose the image, then by using a LUT or boosting the shadows/mids/hi's in a program like Davinci Resolve, you can recover the image. The price you pay with film is, yes, there is more grain (noise) than properly exposing the film. Now, with digital, it's a little different.

I've been drawing the analogy to film by talking about underexposure. With emulsion film, you were better off underexposing than overexposing. With the advent of log gammas, the image information is debayered so that most of the data bits are written/stored in the highlights. The shadow data is sacrificed (in the RAW data) to put more data bits in the highlights(remember that in REC709, you can only have a limited/fixed number of data bits). If you UNDEREXPOSE the image, and boost the gains in post processing, you have to bring up the exposure. The shadows will be horrendously noisy because there wasn't much data there after the debayer process. If you OVEREXPOSE the image, you have to bring the gains down in post processing. This recovers all that data in the hilites and pushes the shadows further into the shadows, so, you don't see the noise that resulted from the reduction in shadow data bits. The overall image, after processing, brings out all the hilite data detail, "crushes" the shadows to hide all the noise; and the image looks better than it would have if a "normal" gamma had been used.


So, the bottom line is that you may want to ETTR (expose to the right of the histogram) in order to concentrate your image data in the hi's, then bring that data back into the washed out looking image with a LUT or by dialing down the gains in the lows, mids, and hi's in Davinci Resolve. You can recover what appears to be lost data because of the high dynamic range of the log exposure. The image, before processing, looks milky, washed out, and over-exposed. You can't judge the exposure by simply looking at the viewfinder. That's the disadvantage of using LOG, unless you can apply a correction LUT to the viewfinder before it's displayed.(side note: I use a ATOMOS FLAME HDR monitor because it doesn't need a LUT to properly display an HDR image; and, a LUT is built into the display) Alternatively, rather than judging the exposure with the image in the viewfinder, you can learn to monitor the histogram, pushing the histogram curve to the right as far as it will go, without blowing the hilites. It will all be recovered in post processing.

One more note, pull processing the digital image acquired with a LOG gamma, will not result in more noise in the image, unless you've over-overexposed the image, resulting in clipped hilites.
Skyeyeguy....the exposure philosophy is to slightly over-expose the image, not underexpose it. Underexposing LOG data is deadly because it amplifies all the noise.
Clear as mud??
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Dr Jon Posted at 2017-3-4 23:06
DJI have already implemented an RGB Parade option on the display and can be selected on the new firmware under camera control

Dr Jon....OMG! u'r right! how cool is THAT? DJI is right on top of things. I just wish they had replace the normal histogram, instead of taking away my FPV view.
2017-3-5
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raven4 Posted at 2017-3-5 04:02
ISO and ev  are not the same thing. However, ISO and GAIN are the same. The analogy can be made to film. On a film camera, the more sensitive the film emulsion is to light, the higher the rated ISO. On a digital sensor, the higher the bias voltage(GAIN), the more sensitive the sensor is to light. In both cases, the price you pay for boosting the gain or having more light sensitivity, the more grain or noise you'll get. High speed film is also grainy.

Likewise, with film, if you take a film stock(which is a fixed ASA or ISO) and intentionally underexpose it, then in processing the film, you can overdevelop the film to recover the image. With digital, the same thing can be done. You can underexpose the image, then by using a LUT or boosting the shadows/mids/hi's in a program like Davinci Resolve, you can recover the image. The price you pay with film is, yes, there is more grain (noise) than properly exposing the film. Now, with digital, it's a little different.

Actually the DLOG is improved in the latest FW.

We will soon release a tutorial to help customers correctly handle the DLOG using Davinci Resolve..
2017-3-5
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Coigreach
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DJI-CAO Posted at 2017-3-5 05:00
Actually the DLOG is improved in the latest FW.

We will soon release a tutorial to help customers correctly handle the DLOG using Davinci Resolve..

I hope this does not take too long as my photography background is struggling with all things video
2017-3-5
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DJI-CAO Posted at 2017-3-5 05:00
Actually the DLOG is improved in the latest FW.

We will soon release a tutorial to help customers correctly handle the DLOG using Davinci Resolve..

Hi CAO --

Can you describe how D-Log is improved in the new firmware?  

For Instance, the  pronounced macroblocking that was visible in H264/65 after application of  a Rec709 LUT at ISO 100, is that now improved with the Locked ISO 500 version? Also, our testing has shown considerable color error in the H264/65 D-Log ( inability to distinguish between similar colors like "dirt" and concrete and other neutral similar shades). Are the improvements in both H264/65 and ProRes? Generally I recommend not using D-Log in the H264/65, but I find the implementation in ProRes to be pretty nice, providing the most accurate color of any of the DJI supplied gammas.

So what parameters have been improved --Dynamic Range, noise, color accuracy? Certainly with the "locking" of the D-Log at ISO500, we'd expect to see more Dynamic range at the expense of higher noise levels in the shadows compared to ISO 100. Your previous post seemed to imply this wasn't the case. I'm holding off doing the update so I can prepare some before/after testing of the various photo/video related issues, so I'd love to know what I should be looking for in improvements. Thanks.
2017-3-5
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Bumping for DJI to reply to the above /\  /\  /\  /\  /\
2017-3-8
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That's a mathematician's answer. And in current situation a very incompetent one, because whoever wrote it doesn't understand what Log is being used for. Let me start with saying that  EVERY CAMERA ON THE MARKET (including Sony that you guys use sensors from) HAS Log AS A PROFILE ACROSS THE ENTIRE ISO RANGE. Now imagine you are a videographer that uses aerial footage as an additional camera indoors and has to match footage to other cameras. D-Log makes matching footage fairly easy. and in some environments you NEED to be shooting at ISO 800 1/60th of a second at f/2.8 at 4K p30. And you NEED it to be in Log so that you can easier match footage with other cameras. That was working great prior to yesterday's update. Please advise the R&D team not to act like they know cameras better than any other manufacturer. Because the only camera that's screwed up like you guys screwed up P4P is by DJI. Don't take away functionality. Add or fix. But don't take away. You just made my P4P a toy. Downgrading the firmware and I await an INTELLIGENT answer from DJI.
2017-3-8
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High ISO = Noise.  Tougher to fix in post.

Bad idea to lock it higher.  Circumstances often suggest other choices.

2017-3-8
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Barry Goyette Posted at 2017-3-5 07:42
Hi CAO --

Can you describe how D-Log is improved in the new firmware?  

The dynamic range of the latest FW is expaned by 0.5ev and the priority of preserving the highlight is increased.

Soon we will provide the demo video and tutorials of dlog workflow.

It helps mapping the raw and ProRes to leading vendors footage like Alexa mini.

2017-3-8
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DJI-CAO Posted at 2017-3-8 07:37
The dynamic range of the latest FW is expaned by 0.5ev and the priority of preserving the highlight is increased.

Soon we will provide the demo video and tutorials of dlog workflow.

This ISO lock does not apply to RAW.. only ProRes and H264 using D-log.... correct?
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DJI-CAO Posted at 2017-3-8 07:37
The dynamic range of the latest FW is expaned by 0.5ev and the priority of preserving the highlight is increased.

Soon we will provide the demo video and tutorials of dlog workflow.

The .5 EV dynamic range improvement is at ISO 500 only I assume, Correct?
That is reference to where it was before ( 10.8 ev or so at ISO 500) which is still lower than the dynamic range of iso 100...@ 12.8ev... so.... ISO 500 is better how?
There are lots of ppl turned off by this "ISO Lock" and to force us to use it for a gain of .5ev is kind of silly...

Why not just have it as a note for the update... "dynamic range improved by .5EV @ iso 500 in DLOG" but.... we can still chage our ISO?
2017-3-8
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Gybo102 Posted at 2017-3-8 08:20
This ISO lock does not apply to RAW.. only ProRes and H264 using D-log.... correct?

Please read my post.

Log gamma affects the exposure. So a total 2.3ev is used to protect the highlight. That means RAW is changed when shooting dlog.
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DJI-CAO Posted at 2017-3-8 16:54
Please read my post.

Log gamma affects the exposure. So a total 2.3ev is used to protect the highlight. That means RAW is changed when shooting dlog.

Ill be honest... I do not understand all the high end wording. can you... or anyone just tell me yes or no.
RAW is RAW... so... locked ISO does not apply there, right?
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raven4
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hmmmm...applying Dlog to RAW is a non-sequitor....now I'm confused....
2017-3-8
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raven4 Posted at 2017-3-8 17:39
hmmmm...applying Dlog to RAW is a non-sequitor....now I'm confused....

ha ha ha

I only asked because he brought up RAW in one of his last post.. wanted to make sure there was nothing hidden... like it applies to RAW as well.
thats all.

This whole thing is a pain in the butt... just give us ISO control moving forward already.
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Gybo102 Posted at 2017-3-8 18:42
ha ha ha

I only asked because he brought up RAW in one of his last post.. wanted to make sure there was nothing hidden... like it applies to RAW as well.

But, if you go to RAW, it gives you the choice of Standard or Dlog. With Dlog, the ISO is fixed. Dlog shouldn't even be an option since Dlog is applied after debayering.
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raven4 Posted at 2017-3-8 19:24
But, if you go to RAW, it gives you the choice of Standard or Dlog. With Dlog, the ISO is fixed. Dlog shouldn't even be an option since Dlog is applied after debayering.

In raw there is no option for DLOG or anything... its.. RAW.
So, I just want to verify... In RAW are we also stuck at iso 500? Since there is no color profile to select, I assume not, but I would like DJI to confirm this.

IMG_9877.JPG
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wait a sec...on my Go4 App, latest firmware, v4.05, when I select cDNG, I get two options, Dlog and Standard. With Dlog, the ISO is fixed. With Standard, it's not fixed.
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raven4 Posted at 2017-3-8 20:20
wait a sec...on my Go4 App, latest firmware, when I select cDNG, I get two options, Dlog and Standard. With Dlog, the ISO is fixed. With Standard, it's not fixed.

Hmm.... interesting... so there is a change not listed? (sorry for the sarcasm) That pic is from the original firmware. I really wish ALL the changes would be put in a change log.

So.. you can shoot RAW in "none" now? is there really a point to that? Why would some one shoot log... with none?

I am not updating my firmware... I DO NOT want a locked ISO.
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I think you're confusing RAW and log. Log(Dlog) is applied to a debayered data stream, like Prores. RAW is linear and cannot have a log gamma applied to it.
So, in other words, if you're shooting cDNG (RAW) there should be NO Dlog option. Dlog applies only to the ProRes recorded material.
As a side note, the RAW data can have a Dlog gamma applied to it, after acquisition, in an NLE to convert it to Prores.

2017-3-8
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Gybo102
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raven4 Posted at 2017-3-8 20:34
I think you're confusing RAW and log. Log(Dlog) is applied to a debayered data stream, like Prores. RAW is linear and cannot have a log gamma applied to it.
So, in other words, if you're shooting cDNG (RAW) there should be NO Dlog option. Dlog applies only to the ProRes recorded material.
As a side note, the RAW data can have a Dlog gamma applied to it, after acquisition, in an NLE to convert it to Prores.

I think what confused me was what you said before... you said you have the option to select Dlog while in cDNG RAW, correct?
Im used to having no option... just raw. But now we have the option for DLOG in RAW?

So, have you tested video with the new firmware? if so.. what is your take on the locked ISO?
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raven4
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What i said was that yes, there is the Dlog option for RAW. But, that's not right. How can that be? RAW isn't video, it's digital data straight from the sensor. Dlog is video that's been extracted from the RAW data and had a log gamma applied to the extraction. The Dlog option is supposed to be applied to a debayered image stream, not to RAW. And, no,  haven't had a chance to check it out, yet. It's been extremely windy here for the last week.
2017-3-9
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