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Interceptor121

The case for dual ISO camera for underwater video

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Interesting article. Thanks Massimo. I would like to add a relative video.

How can I add a video to a post and show the thumbnail/image of video instead of a link?

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16 minutes ago, thani said:

Interesting article. Thanks Massimo. I would like to add a relative video.

How can I add a video to a post and show the thumbnail/image of video instead of a link?

Here? If it is youtube go on the page and press the share button and copy the link instead of copy paste of the browser address 

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Very confusing video that is for some parts inaccurate

Sensitivity does not exist only gain exists the sensor is a bucket that collects photons there are no way to change this bucket by flicking a switch as the sensor is a passive device with nothing moving of flicking

What is there are two separate amplifiers so the terms dual native iso is incorrect it should just be dual gain

The part about dynamic range is correct as you increase gain dynamic range decreases and that is normal because the signal is smaller and you are just amplifying

There is also some debate that noise does not increase when you increase gain the issue was that noise was there as there was less light which is the reason why once you constrain depth of field and field of view large sensors do not have a better SNR

So the noise is not because you raised the ISO but because there was less light and the underlying noise of the sensor stayed the same so the SNR drops

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here is another brief clip from Lumix:

 

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48 minutes ago, thani said:

here is another brief clip from Lumix:

 

This is correct is not the sensor that had two ISO is the camera that has two amplifiers.

In terms of the logic the LOW ISO circuit is actually an amplifier for large signals so has reduced gain, the High ISO circuit is an amplifier for small signals (i.e. photons) by specialising the circuit you make it work best for the range of signal you have.

Increasing Gain (i.e. ISO) does not increase noise the noise is there already but it amplifies signal so that the SNR improves but the dynamic range will drop any time you apply gain

Still you need to understand if there is a case for you, if you shoot below below 1000's gain there is no major benefit of a dual amplifier if you shoot really low light then the dedicated circuit will work better than the general purpose circuit

 

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Thank you for your input. I shoot using GH5s with ambient lights and have the max ISO set at 6400. I think my setting for which ISO value to use is left to the camera to decide (Auto). I always shoot with the widest Iris/Fstop possible. In our home country (UAE) because of the usual bad visibility at depth greater that 20m, the camera usually goes for the max 6400.

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2 hours ago, thani said:

Thank you for your input. I shoot using GH5s with ambient lights and have the max ISO set at 6400. I think my setting for which ISO value to use is left to the camera to decide (Auto). I always shoot with the widest Iris/Fstop possible. In our home country (UAE) because of the usual bad visibility at depth greater that 20m, the camera usually goes for the max 6400.

Definitely a good case for Dual Gain when ISO is anywhere over 800 on the GH5s which I suppose is most of the time except surface

It is the first camera MFT with dual gain the second has been the BMPCC4K however I think the thresholds are different

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@thani and others I have just finished some calculations. Based on Panasonic data and measurements of read noise on photons for photo for what concerns the GH5 vs GH5s the tipping point is 1250

Up to ISO 1250 the GH5 has better dynamic range and SNR from 1600 onwards the GH5s has better SNR around 1 to 3 dB

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On 4/24/2020 at 7:44 PM, Interceptor121 said:

@thani and others I have just finished some calculations. Based on Panasonic data and measurements of read noise on photons for photo for what concerns the GH5 vs GH5s the tipping point is 1250

Up to ISO 1250 the GH5 has better dynamic range and SNR from 1600 onwards the GH5s has better SNR around 1 to 3 dB

News shooter.com arrived to the same conclusion:

“Dual Native ISO

Borrowing from the VariCam. Panasonic added Dual Native ISO. This feature gives the sensor a second set of circuits for better ISO performance when changing them from Low to High. Better means cleaner. You have three settings. Auto, Low and High. I found the Low ISO levels to be very similar to the GH5. In fact, I feel the GH5 might be a hair cleaner. It’s when you get to 1600 ISO where the GH5S seems to clean up but also the image gets smoother as noise reduction starts to increase with every step up.”

https://www.newsshooter.com/2018/02/22/panasonic-gh5s-good-bad-clean/

According to the research I’ve done and my own experience the GH5s is usable up to ISO 6400. And it can manually white balance correctly with a red filter at depth of 30 meters in our unclear waters.

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14 hours ago, thani said:

News shooter.com arrived to the same conclusion:

“Dual Native ISO

Borrowing from the VariCam. Panasonic added Dual Native ISO. This feature gives the sensor a second set of circuits for better ISO performance when changing them from Low to High. Better means cleaner. You have three settings. Auto, Low and High. I found the Low ISO levels to be very similar to the GH5. In fact, I feel the GH5 might be a hair cleaner. It’s when you get to 1600 ISO where the GH5S seems to clean up but also the image gets smoother as noise reduction starts to increase with every step up.”

https://www.newsshooter.com/2018/02/22/panasonic-gh5s-good-bad-clean/

According to the research I’ve done and my own experience the GH5s is usable up to ISO 6400. And it can manually white balance correctly with a red filter at depth of 30 meters in our unclear waters.

Might be an interesting idea to meet and dive the same spot Thani and comparing the GH5 and GH5s image under the same conditions and same scenes. When diving opens up again in the area. 

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15 hours ago, thani said:

News shooter.com arrived to the same conclusion:

“Dual Native ISO

Borrowing from the VariCam. Panasonic added Dual Native ISO. This feature gives the sensor a second set of circuits for better ISO performance when changing them from Low to High. Better means cleaner. You have three settings. Auto, Low and High. I found the Low ISO levels to be very similar to the GH5. In fact, I feel the GH5 might be a hair cleaner. It’s when you get to 1600 ISO where the GH5S seems to clean up but also the image gets smoother as noise reduction starts to increase with every step up.”

https://www.newsshooter.com/2018/02/22/panasonic-gh5s-good-bad-clean/

According to the research I’ve done and my own experience the GH5s is usable up to ISO 6400. And it can manually white balance correctly with a red filter at depth of 30 meters in our unclear waters.

Well is good that I can draw some hypothesis without having the camera. The Gh5 has a PGA with 36 dB range plus 6 dB extended the Gh5s has 50 dB plus 18 dB extended. Those 14 dB mean 2 stops and 1/2 so 1250 add two stops 5000 plus one third 6400 am spot on.

It is important to understand that SNR improves because the amplifier makes S the signal larger, it is not noise reduction to go up. Noise is in fact going up but the amplifier makes the signal go up more in proportion

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1 hour ago, Lionfi2s said:

Might be an interesting idea to meet and dive the same spot Thani and comparing the GH5 and GH5s image under the same conditions and same scenes. When diving opens up again in the area. 

Sure, it is a good idea. Hopefully they open up diving soon. I am hopeful that after Ramadan, life will resume gradually. 

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