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Mark Romero 2

So Is a7 III Still The Dynamic Range King? (Not tolling, just asking)

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1 hour ago, androidlad said:

Do you know what ADC is? ADC bitdepth directly determines how much DR can be extracted from the sensor. Sony sensors use single 12bit ADC for video. The new BMD 4.6K G2 uses dual 11bit ADC, ARRI uses dual 14bit ADC.

You clearly don't know what ADC is. Your 12 bit ADC can cover 1000 stops of DR if necessary. There would just be big steps instead of little steps.

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52 minutes ago, androidlad said:

12bit ADC places an upper limit on the DR, which is 12 stops. Current silicon based sensors work in linear, so 1bit=1 stop.

It's not going to do any good if both of us to keep repeating ourselves.  I'll try a different explanation.

 

In the first place, dynamic rage was originally a property of analog systems to indicate the useful amplitude range rated in decibels (not "stops").  It is similar to the property of signal-to-noise ratio in that it gives some idea of the useful amplitude range above the noise floor.  DR now applies both to analog and digital systems.

 

Bit depth on the other hand is strictly a digital property that simply gives the number digital level increments mapped to an amplitude range (usually including the noise floor).

 

So, the useful amplitude range (analog or digital) and the number of digital increments mapped to the entire amplitude range are two very different, independent properties.  The noise floor of the sensor and/or ADC determines the actual dynamic range at that point in a camera's signal pipeline -- not the number digital level increments mapped (log, linear, whatever) to the signal's amplitude range.

 

 

52 minutes ago, androidlad said:

It seems that you're confusing linear ADC bitdepth with encoding curve bitdepth which can be log or linear or anything in between (for example, BRAW is non-linear RAW)

Or perhaps we are confusing usable capture contrast range with dynamic range.

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Those stops y'all are debating over are going to fall apart fast in any real attempt to recover highlights/shadows, let alone gamut remapping and color pushing.

The science is there to make it possible (Canon does well enough to with 8 bit in C series, d750 was nice enough) but as long as they're dropped in these heavily compressed mirrorless codecs...you might as well keep that noise floor crushed to blacks imo.

Trade color for stretched thin DR? On you

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58 minutes ago, Mokara said:

You clearly don't know what ADC is. Your 12 bit ADC can cover 1000 stops of DR if necessary. There would just be big steps instead of little steps.

 

52 minutes ago, tupp said:

It's not going to do any good if both of us to keep repeating ourselves.  I'll try a different explanation.

 

In the first place, dynamic rage was originally a property of analog systems to indicate the useful amplitude range rated in decibels (not "stops").  It is similar to the property of signal-to-noise ratio in that it gives some idea of the useful amplitude range above the noise floor.  DR now applies both to analog and digital systems.

 

Bit depth on the other hand is strictly a digital property that simply gives the number digital level increments mapped to an amplitude range (usually including the noise floor).

 

So, the useful amplitude range (analog or digital) and the number of digital increments mapped to the entire amplitude range are two very different, independent properties.  The noise floor of the sensor and/or ADC determines the actual dynamic range at that point in a camera's signal pipeline -- not the number digital level increments mapped (log, linear, whatever) to the signal's amplitude range.

 

 

Or perhaps we are confusing usable capture contrast range with dynamic range.

Sensors work in linear, even if the analog components (photosites) are capable of 10000000 stops, a single 12bit ADC would only be able to produce max 12 stops in digital signal.

Sony's IMX490 is capable of 120dB DR, that's achieved by three 10bit ADC working simultaneously.

https://www.dpreview.com/articles/4653441881/bit-depth-is-about-dynamic-range-not-the-number-of-colors-you-get-to-capture

Have a read and educate yourselves gentlemen.

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15 minutes ago, androidlad said:

 

Sensors work in linear, even if the analog components (photosites) are capable of 10000000 stops, a single 12bit ADC would only be able to produce max 12 stops in digital signal.

Sony's IMX490 is capable of 120dB DR, that's achieved by three 10bit ADC working simultaneously.

https://www.dpreview.com/articles/4653441881/bit-depth-is-about-dynamic-range-not-the-number-of-colors-you-get-to-capture

Have a read and educate yourselves gentlemen.

A ADC converts a analog signal into digital code. If your sensor can measure 1000 stops of dynamic range (as in, be able to accurately measure a low non zero quantity and a high quantity, the difference between which is your dynamic range), your ADC will convert that analog response into bits covering that range. An individual bit does NOT correspond to a stop of DR range. It could be the equivalent of 10 stops or it could be 0.1 stops. It is completely arbitrary. You could use a 12 bit ADC for your 11 stop DR sensor, or you could use a 256 bit ADC for it, or you could use a 4 bit ADC. The only thing that would change is the size of the steps between the highest and lowest analog value your sensor can detect. 

If your sensor had a 1000 stop DR, your 12 bit ADC would generate a digital version of that analog signal with 4096 possible values. The size of those 4096 steps will vary depending on what the dynamic range of your sensor actually is. If it 4 stops, those 4096 steps will correspond to small increments of the response, if it has 1000 stops, those 4096 steps will correspond to large increments of the response.

 

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2 hours ago, androidlad said:

The Possession of Hannah Grace, shot on A7S II in 8bit, looks gorgeous.

...and scary...

28 minutes ago, Mokara said:

A ADC converts a analog signal into digital code. If your sensor can measure 1000 stops of dynamic range (as in, be able to accurately measure a low non zero quantity and a high quantity, the difference between which is your dynamic range), your ADC will convert that analog response into bits covering that range. An individual bit does NOT correspond to a stop of DR range. It could be the equivalent of 10 stops or it could be 0.1 stops. It is completely arbitrary. You could use a 12 bit ADC for your 11 stop DR sensor, or you could use a 256 bit ADC for it, or you could use a 4 bit ADC. The only thing that would change is the size of the steps between the highest and lowest analog value your sensor can detect.  

If your sensor had a 1000 stop DR, your 12 bit ADC would generate a digital version of that analog signal with 4096 possible values. The size of those 4096 steps will vary depending on what the dynamic range of your sensor actually is. If it 4 stops, those 4096 steps will correspond to small increments of the response, if it has 1000 stops, those 4096 steps will correspond to large increments of the response.

 

Ok, so the dynamic range is the height distance between the ground floor and the top floor, and the bit depth of the ADC is the number of steps the staircase has that goes from the ground floor to the top floor???

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16 minutes ago, Mark Romero 2 said:

...and scary...

Ok, so the dynamic range is the height distance between the ground floor and the top floor, and the bit depth of the ADC is the number of steps the staircase has that goes from the ground floor to the top floor???

Right. Your dynamic range could be a foot or it could be a mile. ADC bits are the "ticks" on those scales when those distances are converted into a digital code. A bit in itself has no inherent size. A 12 bit tick on your foot ruler does not represent the same quantity as a 12 bit tick on your mile ruler.

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4 hours ago, androidlad said:

The Possession of Hannah Grace, shot on A7S II in 8bit, looks gorgeous.

I heard the movie was ass but cinematic speaking it looks awesome. Just goes to show that lighting, camera movement, and lens choice are more important than the camera itself.

 

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I have a a7iii + ninja V as my main video camera setup (and a a7rii for photo )

i got the a7rii when I still had my blackmagic ursa mini 4.6k .

the a7rii in slog 2 had a bit more DR thank the ursa mini in pro res , so I sold the ursa ( mostly because of the form factor and the video autofocus)

The a7iii is a killer camera , I shoot HLG with it because I found Slog 2 to be unusable ( too much chroma noise , even externally) , but in resolve I do a color space transform back to slog3 and use the Venice rec 709 Lut , so you get great colors.

Dynamic range is really not an issue anymore on modern camera , I don t believe that the Alexa is that much better anymore , but it still have a nicer roll off in the highlights when it clip .

 

The roll off is more important than the dynamics range at that point , also realistically Film only have 11 stop , so it s hard to blame mordern cameras over analog for DR.

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41 minutes ago, Laurier said:

I have a a7iii + ninja V as my main video camera setup (and a a7rii for photo )

i got the a7rii when I still had my blackmagic ursa mini 4.6k .

the a7rii in slog 2 had a bit more DR thank the ursa mini in pro res , so I sold the ursa ( mostly because of the form factor and the video autofocus)

The a7iii is a killer camera , I shoot HLG with it because I found Slog 2 to be unusable ( too much chroma noise , even externally) , but in resolve I do a color space transform back to slog3 and use the Venice rec 709 Lut , so you get great colors.

Dynamic range is really not an issue anymore on modern camera , I don t believe that the Alexa is that much better anymore , but it still have a nicer roll off in the highlights when it clip .

 

The roll off is more important than the dynamics range at that point , also realistically Film only have 11 stop , so it s hard to blame mordern cameras over analog for DR.

Have you ever compared it to an Alexa? I am guessing the Sony probably has cleaner shadows but I doubt you get much highlight information. 

Also I've never heard filming only have 11 stops. I've heard people say Film has similar dynamic range to an Alexa. 

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1 hour ago, thebrothersthre3 said:

Have you ever compared it to an Alexa? I am guessing the Sony probably has cleaner shadows but I doubt you get much highlight information. 

Also I've never heard filming only have 11 stops. I've heard people say Film has similar dynamic range to an Alexa. 

It's closer than you'd think. I've compared the Alexa and the A7S. If you properly expose an A7S at 3200 ISO in SLOG 2 (base ISO on the A7S; haven't used the A7III, but I suspect it's similar) and expose the same scene at 800 ISO on an Alexa (its base ISO, so open up two stops), the Alexa should have 1.4-1.8 more stops of highlight detail. I believe the Alexa has an over of +7.4 at base ISO or +7.8 maybe depending on what model it is (original vs Mini or Amira or something, or maybe it depends on firmware but Arri quotes different numbers) and the A7S I think has an over of +6 at base ISO (3200 ISO) in SLOG 2. Not 100% sure of this but it's what I found online and it correlates with what I've seen pretty well.

On the other hand, I think SLOG 3 looks better than SLOG 2 because its base ISO is pulled to 1600 (or something, I'm not as technical as I used to be), and as a result it clips one stop sooner but looks cleaner. If you expose the A7S at 3200 ISO with an incident meter the image will look super underexposed, and that's how it gets that excellent highlight detail. Not sure about HLG, but I suspect it clips sooner, too, and has better tonality. The best image I've seen out of the A7S was SLOG 2 pulled two stops on a Q7+ external recorder, so it had +4 but was incredibly clean. Regardless, even +4 is good for mirrorless. +6 is good for a cinema camera. +7.8 is ridiculous.

I don't like SLOG 2 at all, and I don't like how it clips aesthetically (especially how colors clip), but it does offer good highlight detail. I'm excited for the A7S III and would love to rent one and shoot in zero light with one of those f0.95 lenses. I just hope they address skew and how colors clip and offer a 10 bit option, that would be an amazing camera.

Disclaimer: this stuff is changing so fast I'm sure I'm getting details wrong and am in over my head. But the A7 cameras, exposed properly at base ISO in SLOG 2, have very good highlight detail... but they look better overexposed IMO so maybe it's irrelevant. Regardless, the Alexa is still in a whole different league, but you also can't carry one around with you easily.

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1 hour ago, thebrothersthre3 said:

Have you ever compared it to an Alexa? I am guessing the Sony probably has cleaner shadows but I doubt you get much highlight information. 

Also I've never heard filming only have 11 stops. I've heard people say Film has similar dynamic range to an Alexa. 

Well a lot of places claim 13 to 14 stops for film, but it is overrated just like Digital cameras are.  In reality you can take off 2 stops on all of them and be pretty close in reality. So the 11 stops, maybe 12 are probably realistic for film. The A7s probably is more like 12.5 in reality, so it is close. Alexa probably is 13.5 stops. Trouble is there is no real true method for any of it. I think Highlight roll off is more important than DR. But you need both, and that is what makes an Arri King of the hill. Red cameras seem to have more DR but their Highlight roll off is not so hot I think. I am really not a big fan of their look output wise. It is more brutal than smooth.

But high DR numbers is not so much of a big deal. Look at the Canon C100, probably 11 stops tops @ 24mbs at 8bit.. Defies logic.

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51 minutes ago, webrunner5 said:

Well a lot of places claim 13 to 14 stops for film, but it is overrated just like Digital cameras are.  In reality you can take off 2 stops on all of them and be pretty close in reality. So the 11 stops, maybe 12 are probably realistic for film. The A7s probably is more like 12.5 in reality, so it is close. Alexa probably is 13.5 stops. Trouble is there is no real true method for any of it. I think Highlight roll off is more important than DR. But you need both, and that is what makes an Arri King of the hill. Red cameras seem to have more DR but their Highlight roll off is not so hot I think. I am really not a big fan of their look output wise. It is more brutal than smooth.

But high DR numbers is not so much of a deal. Look at the Canon C100, probably 11 stops tops.

 

I agree. I think the C100 has +5.3 for highlight detail. That's the official number. It looks pretty good exposed at base ISO, but most people seem to overexpose with it. AVCHD muddies up the shadows so I get why. I agree that the A7S has more dynamic range overall, but I'm not 100% sure since I never put them side by side.

I think the Alexa really might be 14-15 stops total but the shadows are so noisy you can’t push them far. So you can see the detail there very faintly, but it’s not really detail you can recover, at least without denoising or something. So it’s tough to know what the real number is. The detail might really be there in the shadows, but if boosting the exposure makes the image too muddy to use, how much does it count? That’s why I think stops over 18% gray at base ISO is a more useful measure. Since it's more obvious when highlights are clipping. Not so obvious where the noise floor is exactly. And generally base ISO is where the image looks good and where most people shoot.

(Except imo SLOG 2 looks much better overexposed by a stop, so that complicates things.)

In terms of highlight detail, the Alexa is still way ahead, yeah. Next best is Varicam at +6.5 I think. But you rarely need that much anyway. The A7S has a lot of highlight detail, though, especially if you're good at working with SLOG 2, which I'm not.

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In the comparison's I've seen with Red vs Alexa, the red clipped the highlights faster. Wasn't their latest sensors though. 

Dynamic range is just very subjective. For example comparing my XT3 to my BM pocket(og not 4k) they both have pretty similar dynamic range, the XT3 being cleaner. The Pocket shadows look nicer though once recovered, there is just more color you can get back into them even though its noisier. My experience at least. 

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I've uploaded test for X-T3 and Z6. It was based on cinematography.net testing method. Highlights range is clear there, while the shadows range is open to anyone's interpretation... 

 

 

 

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17 hours ago, Laurier said:

 

The a7iii is a killer camera , I shoot HLG with it because I found Slog 2 to be unusable ( too much chroma noise , even externally) , but in resolve I do a color space transform back to slog3 and use the Venice rec 709 Lut , so you get great colors.

 

Dude, you're on to something.... I just tried that workflow and the results are really, really good. Thanks for posting this.

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I saw people doing color space transforms to Alexa , it work quite well. 

But the thing is that Sony basically said that the Venice sensor is the a9 sensor.

So my reasoning is that the a9 sensor output very similar colors as the a7iii and a fair amount of the cine Alta color science is actually in the last LUT they provided.

Since IMO the slog3 is unusable on the A7iii, using color space transform just to remap the colors from HLG to slog3 give you the best of both world , a profile easy to expose with a lot of DR and the best colors science Sony have to offer .

It s definitely nicer on the skin tones and the green colors when you shoot nature .

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15 hours ago, Zeng said:

I've uploaded test for X-T3 and Z6. It was based on cinematography.net testing method. Highlights range is clear there, while the shadows range is open to anyone's interpretation... 

 

 

The highlight retention looks the same. XT3 does look quite a bit better in the shadows though. 

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Like I said, this is very subjective. For instance, based on how Geoff Boyle discards the stops under, overall X-T3 wouldn't have any more stops beyond the charts. However, if you find acceptable strong color loss you may say X-T3 has more controlled noise with less chroma in it, and thus a bit more in the shadows. I'd say, total range is about equal with Fuji having less color and less noise, and Z6 having better color and uglier noise.

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