A7Siii with slog, zebras not working

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Seanocaster New Member • Posts: 24
A7Siii with slog, zebras not working

Has anyone else noticed that when you're shooting 4K video on the A7Siii using slog3 and you shoot at a custom ISO 160, the zebras won't work no matter how overexposed it becomes. I've tried with zebras at various settings and with that ISO they are not visible.

From what I have noticed, this only happens at ISO's below 320. As soon as you hit ISO 320 (and upwards) the zebras come back.

This is super dangerous. Last week I did a shoot and I miscalculated the exposure and all the footage is overexposed. Plus, the exposure meter was showing +1.3 only which is within range for slog.

Lesson learnt, will not be relying on that meter anymore!

Does anyone know if false colour is an option on the Sony A7Siii ?

Entropy512 Veteran Member • Posts: 5,224
Re: A7Siii with slog, zebras not working

Seanocaster wrote:

Has anyone else noticed that when you're shooting 4K video on the A7Siii using slog3 and you shoot at a custom ISO 160, the zebras won't work no matter how overexposed it becomes. I've tried with zebras at various settings and with that ISO they are not visible.

From what I have noticed, this only happens at ISO's below 320. As soon as you hit ISO 320 (and upwards) the zebras come back.

This is super dangerous. Last week I did a shoot and I miscalculated the exposure and all the footage is overexposed. Plus, the exposure meter was showing +1.3 only which is within range for slog.

Lesson learnt, will not be relying on that meter anymore!

Does anyone know if false colour is an option on the Sony A7Siii ?

So wait... Did they completely redo how S-Log3 works on the S3?

Because anything below ISO800 is disallowed on other cameras. (mainly because the ISO rating is derived from the JPEG midpoint, and for S-Log3, that corresponds to a sensor gain configuration that is ISO100 for normal sRGB/rec709 due to the midpoint being so far down from the clip point for S-Log)

I can't see how they could implement S-Log3 below 800 on the S3 unless they're doing some funky extended-fake-ISO stuff like running the sensor at ISO100 still and then dividing the data before feeding it into the S-Log3 transform function. Which is just silly because you're going to be losing dynamic range by doing this.

Edit: Apparently the S3 dropped the sensor's minimum ISO to 80, which drops the S-Log3 minimum without hackery/fakery to 640...

Try doing some RAW+JPEG shots at ISO640 and below, and look at:

1) What the actual RAW data is doing below 640. You may see that it stops changing, indicating "fake extended ISO" behavior and also explaining why zebras break since they're derived from the JPEG/video data after the output transform

2) What the "Sony ISO" metadata tag is reporting (this is not the same as ISO - for example, on all of my cameras, ISO800 for S-Log3 reports a "Sony ISO" of 100 in the ARW files)

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jonpais
jonpais Veteran Member • Posts: 3,069
Re: A7Siii with slog, zebras not working

Seanocaster wrote:

Has anyone else noticed that when you're shooting 4K video on the A7Siii using slog3 and you shoot at a custom ISO 160, the zebras won't work no matter how overexposed it becomes. I've tried with zebras at various settings and with that ISO they are not visible.

From what I have noticed, this only happens at ISO's below 320. As soon as you hit ISO 320 (and upwards) the zebras come back.

This is super dangerous. Last week I did a shoot and I miscalculated the exposure and all the footage is overexposed. Plus, the exposure meter was showing +1.3 only which is within range for slog.

Lesson learnt, will not be relying on that meter anymore!

Does anyone know if false colour is an option on the Sony A7Siii ?

Zebras work just fine

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Entropy512 Veteran Member • Posts: 5,224
Re: A7Siii with slog, zebras not working

jonpais wrote:

Seanocaster wrote:

Has anyone else noticed that when you're shooting 4K video on the A7Siii using slog3 and you shoot at a custom ISO 160, the zebras won't work no matter how overexposed it becomes. I've tried with zebras at various settings and with that ISO they are not visible.

From what I have noticed, this only happens at ISO's below 320. As soon as you hit ISO 320 (and upwards) the zebras come back.

This is super dangerous. Last week I did a shoot and I miscalculated the exposure and all the footage is overexposed. Plus, the exposure meter was showing +1.3 only which is within range for slog.

Lesson learnt, will not be relying on that meter anymore!

Does anyone know if false colour is an option on the Sony A7Siii ?

Zebras work just fine

Did you reconfigure PP3 to be S-Log3?  Because by default, that is Rec709.

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OP Seanocaster New Member • Posts: 24
Re: A7Siii with slog3, zebras not working

Well spotted, please try the same with pp8 which is slog3

OP Seanocaster New Member • Posts: 24
Re: A7Siii with slog, zebras not working

I have only recently become a Sony user (canon/panasonic/black magic before). And to be clear, I'm referring to video, not photo.

It is a known fact that slog3 works with ISO 100 and above, it's part of the menu system. And I've done 10+ shoots already using these settings. However, if you put ISO on auto it will not go below 640.

Entropy512 Veteran Member • Posts: 5,224
Re: A7Siii with slog, zebras not working

Seanocaster wrote:

I have only recently become a Sony user (canon/panasonic/black magic before). And to be clear, I'm referring to video, not photo.

It is a known fact that slog3 works with ISO 100 and above, it's part of the menu system. And I've done 10+ shoots already using these settings. However, if you put ISO on auto it will not go below 640.

Run some tests.  I'm 90% certain there is fakery going on there because of the nature of how S-Log3 works.

Just like "extended ISO" settings are almost always useless/bogus, anything below 640 is likely to be doing strange/unusual things because the sensor can't go below 80.

The S3 the first camera I've ever heard of that allowed S-Log3 below "minimum normal ISO times 8" - or in the case of the S3, 640.  (Most other Sonys bottom out their real ISO range at 100, so disallow S-Log3 below 800).  There's no way for them to allow this without doing some sort of strange fakery, such as running the sensor at the same gain settings for all ISOs below 640, and scaling the data afterwards, so the metering changes.  This will result in the JPEG data not hitting full-scale, which will break zebras.

If you really need to drop below 640, unless you can ABSOLUTELY confirm the sensor gain settings are actually changing in a meaningful way below this (I doubt it), you should use an ND filter.

I know you do video, but to figure out the actual behavior of the camera in these regions that shouldn't be permitted (and aren't on any other Sony), you need to run a few quick RAW+JPEG stills experiments in the same PP mode.  I'm fairly certain you'll find evidence that confirms that anything below 640 is employing fakery/tricks similar to how some cameras have fake "extended ISOs" below minimum native.

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Markr041 Veteran Member • Posts: 9,027
No, zebras are not working when you shoot below the base ISO of SLOG3

Seanocaster wrote:

Has anyone else noticed that when you're shooting 4K video on the A7Siii using slog3 and you shoot at a custom ISO 160, the zebras won't work no matter how overexposed it becomes. I've tried with zebras at various settings and with that ISO they are not visible.

From what I have noticed, this only happens at ISO's below 320. As soon as you hit ISO 320 (and upwards) the zebras come back.

This is super dangerous. Last week I did a shoot and I miscalculated the exposure and all the footage is overexposed. Plus, the exposure meter was showing +1.3 only which is within range for slog.

Lesson learnt, will not be relying on that meter anymore!

Does anyone know if false colour is an option on the Sony A7Siii ?

Why are you shooting in Slog3 below the base ISO? The image will be degraded below the base. That is not a good idea for any reason.

My point is that not having zebras for ISO's below the base is not a problem for anyone using the PP appropriately. Or, tell me I am wrong? In any case your headline is misleading.

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Entropy512 Veteran Member • Posts: 5,224
Re: No, zebras are not working when you shoot below the base ISO of SLOG3

Markr041 wrote:

Seanocaster wrote:

Has anyone else noticed that when you're shooting 4K video on the A7Siii using slog3 and you shoot at a custom ISO 160, the zebras won't work no matter how overexposed it becomes. I've tried with zebras at various settings and with that ISO they are not visible.

From what I have noticed, this only happens at ISO's below 320. As soon as you hit ISO 320 (and upwards) the zebras come back.

This is super dangerous. Last week I did a shoot and I miscalculated the exposure and all the footage is overexposed. Plus, the exposure meter was showing +1.3 only which is within range for slog.

Lesson learnt, will not be relying on that meter anymore!

Does anyone know if false colour is an option on the Sony A7Siii ?

Why are you shooting in Slog3 below the base ISO? The image will be degraded below the base. That is not a good idea for any reason.

My point is that not having zebras for ISO's below the base is not a problem for anyone using the PP appropriately. Or, tell me I am wrong? In any case your headline is misleading.

I'm really surprised Sony even allowed people to do this...  It's been disallowed on nearly every other S-Log2/3 enabled Sony camera.

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jonpais
jonpais Veteran Member • Posts: 3,069
Re: A7Siii with slog3, zebras not working

Seanocaster wrote:

Well spotted, please try the same with pp8 which is slog3

It is S-Log3.

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OP Seanocaster New Member • Posts: 24
Re: No, zebras are not working when you shoot below the base ISO of SLOG3

I can't speak for other Sony cameras because I'm new to the Sony world. But I've seen videos on YouTube of people shooting at ISO 160 so it's legit.

Would love to see if someone with the A7Siii could put it onto PP8 with ISO 250 or less and tell me if you see zebras... over expose the hell out of it and let me know.

Entropy512 Veteran Member • Posts: 5,224
Re: No, zebras are not working when you shoot below the base ISO of SLOG3
1

Seanocaster wrote:

I can't speak for other Sony cameras because I'm new to the Sony world. But I've seen videos on YouTube of people shooting at ISO 160 so it's legit.

Would love to see if someone with the A7Siii could put it onto PP8 with ISO 250 or less and tell me if you see zebras... over expose the hell out of it and let me know.

Just because someone did something on YouTube doesn't mean you should...

Seriously, what you are doing was explicitly disallowed for good reason for nearly every other Sony camera that had S-Log capability.  The issues you're having are exactly why Sony should have continued the practice of not letting you even try to do it.

Again - run some tests to verify what is actually happening with your camera, don't just trust what some YouTuber said.  Specifically, look to see if, when you run some quick tests with fixed (manual) shutter and aperture, whether or not you see any change in the behavior of RAW exposures when shooting RAW+JPEG.  If you see no change below 640 (and I suspect this will be the case), it's a surefire sign of bogus "extended ISO" fakery that you should be avoiding.

There's really only one way I can think of for Sony to have implemented S-Log2/3 below 8xMinNormalISO, and that way would cause EXACTLY the problems you are describing and are a gigantic warning sign to say "stop doing this".

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Markr041 Veteran Member • Posts: 9,027
Do Not shoot Slog3 Below the Base ISO

Seanocaster wrote:

I can't speak for other Sony cameras because I'm new to the Sony world. But I've seen videos on YouTube of people shooting at ISO 160 so it's legit.

Would love to see if someone with the A7Siii could put it onto PP8 with ISO 250 or less and tell me if you see zebras... over expose the hell out of it and let me know.

The issue is not whether shooting with ISO's below the base ISO is "legit." You got burned for doing something you should not have. It is totally irrelevant whether zebras show up when shooting below base ISO.

Do not do what you did again, and move on.

You are wasting your time in pursuing this, and our time - we are trying to help you with more important information than zebras.

Now we better understand why Sony locks off those ISO's in some cameras - to prevent those who do not understand what they are doing from making mistakes that will degrade results and then blame it on the camera. We are sorry you got burned. Now learn from it.

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OP Seanocaster New Member • Posts: 24
Re: Do Not shoot Slog3 Below the Base ISO
1

Thanks for the replies.

You guys are of course right. Lesson learnt, moving on.

jonpais
jonpais Veteran Member • Posts: 3,069
Zebras work just fine: I just shared a photo. smh

Hi Labe: The OP is gaslighting.

All the commenters are mistaken

Zebras do work below base ISO.

I even took a photo of the back of my camera showing zebras working with S-Log3 at ISO 160.

Regards,

Jon

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Markr041 Veteran Member • Posts: 9,027
Re: Zebras work just fine: I just shared a photo. smh
1

jonpais wrote:

Hi Labe: The OP is gaslighting.

All the commenters are mistaken

Zebras do work below base ISO.

I even took a photo of the back of my camera showing zebras working with S-Log3 at ISO 160.

Regards,

Jon

No, all the commenters are not mistaken - you missed the point: the point is there is no good reason to shoot below the base ISO when shooting Slog3. That is the point made, again and again, by commenters. So no one bothered but you to check for the completely irrelevant fact of whether zebras do or do not show up below base ISO.

And, the OP was not gaslighting;  he genuinely did not know about the folly of shooting this way, and says he learned his lesson (see his last post). So, this was a successful dialogue, with genuine information, until your post.

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Entropy512 Veteran Member • Posts: 5,224
Re: Zebras work just fine: I just shared a photo. smh

Markr041 wrote:

jonpais wrote:

Hi Labe: The OP is gaslighting.

All the commenters are mistaken

Zebras do work below base ISO.

I even took a photo of the back of my camera showing zebras working with S-Log3 at ISO 160.

Regards,

Jon

No, all the commenters are not mistaken - you missed the point: the point is there is no good reason to shoot below the base ISO when shooting Slog3. That is the point made, again and again, by commenters. So no one bothered but you to check for the completely irrelevant fact of whether zebras do or do not show up below base ISO.

And, the OP was not gaslighting; he genuinely did not know about the folly of shooting this way, and says he learned his lesson (see his last post). So, this was a successful dialogue, with genuine information, until your post.

Yup.  Most notably, his picture (Showing zebras in PP3) led to a whole bunch of questions:

PP3 is normally not an S-Log3 mode unless someone has made significant settings changes to the camera.

What was the zebras config in Jon's picture?  Was it one that people would consider "normal" for a zebras config, or an unusually low threshold for activation?  After all, Jon could have mangled settings in such a way as to show an example of zebras working with S-Log3 but in a configuration no sane person would use.

As you have pointed out, there's a lot wrong with attempting to use S-Log3 at an ISO less than 8xMinNormalISO (I can't think of a better term than "minimum normal ISO" to describe the camera's minimum ISO when no picture profiles are in play, since ISO is defined based on JPEG transfer function, and S-Log3's transfer function inherently changes the effective ISO of the JPEG even for a fixed sensor gain configuration).

Having zebras work inconsistently is just one example of this.  For example, to implement this, Sony is likely putting the sensor in ISO 80 mode (corresponds to S-Log3 ISO640) and then multiplying all values by FakeEV/640 before applying the S-Log3 transfer function.

This means that the clip point of the sensor will no longer map to the maximum S-Log3 code value, which will likely break any zebras set in the 90+ range, but if you set a much lower zebras threshold, they may work again.

Ideally we'd have the option of zebras and histogram derived from raw sensor data, but Sony refuses to give that to us.    Meanwhile, they remove a function lockout that was there for very good reasons...

I personally believe that the OP did indeed encounter the issue they claim to be having, and that particular issue was just one of many warning signs of why one should not use fake/extended ISO modes.

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jonpais
jonpais Veteran Member • Posts: 3,069
S-Log3 ISO 160 Looks Perfect
2

ISO 160 looks perfect to me: great colors, skin tones, contrast, detail, low noise. In a pinch, if I didn't have an ND filter, I wouldn't hesitate to use ISO 160.

Insisting everyone shoot at base ISO is a little bit like telling everyone they've got to close their lens down two stops or they've got to always use a certain picture profile: there are times when you've got no choice but to break the rules. Which is why it's a good idea for each person to perform their own tests.

Maybe the menu on your camera is frozen; or your astrologer warned you to avoid the numbers six, four and zero; or your fiancé drove your pickup over your ND filter... As long as you're aware that you'll only be capturing the dynamic range of S-Cinetone (but with richer color). LOL

And to the OP: no, the a7s III does not have false color!!

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