Jump to content
Patrick B.

Simultaneous dual gain sensors

Recommended Posts

I’m curious why simultaneous dual gain sensor architectures a la the Alexa Alev III aren’t more common in smaller cameras.  This allows a low and high ISO signal to be combined for one HDR image. It seems that in ten years most cameras still can’t match the Alexa for sheer video dynamic range, yet CMOS sensor technology has obviously evolved in many ways.

Is there a limiting factor like size/heat, a patent, or maybe otherwise?  Perhaps it’s just that the average consumer is more interested in increased resolution? We now are seeing the switchable dual gain architecture used more, but I’m not aware of lower end cameras using simultaneous dual gain. 

Related info:

https://www.arri.com/en/learn-help/technology/alev-sensors

 

Share this post


Link to post
Share on other sites
EOSHD Pro Color for Sony cameras EOSHD Pro LOG for Sony CamerasEOSHD C-LOG and Film Profiles for All Canon DSLRs

I think I read that the Ursa mini 4.6/pro/G2 use the same approach but with two 11 bits signals rather than 14 from the Alexa, but I m no expert.

I would not be surprised if the power consumption/heat is greater, or if the cost of the sensor is not higher.

 

But modern Dual gain architecture is something different if I understand it properly, it was developed by a third party company, and they licence the technology to sensor manufacturer and I think it s both a software and a hardware thing, it I think it map the dynamic range in a different way, you loose in the highlight but gain in the shadows. I think the sensor only do a single readout with this technology.

Share this post


Link to post
Share on other sites
3 hours ago, Patrick B. said:

I’m curious why simultaneous dual gain sensor architectures a la the Alexa Alev III aren’t more common in smaller cameras.  This allows a low and high ISO signal to be combined for one HDR image. It seems that in ten years most cameras still can’t match the Alexa for sheer video dynamic range, yet CMOS sensor technology has obviously evolved in many ways.

Is there a limiting factor like size/heat, a patent, or maybe otherwise?  Perhaps it’s just that the average consumer is more interested in increased resolution? We now are seeing the switchable dual gain architecture used more, but I’m not aware of lower end cameras using simultaneous dual gain. 

Related info:

https://www.arri.com/en/learn-help/technology/alev-sensors

 

The Sigma fp will have simultaneous dual gain sensor for HDR. I believe the Z-Cam also offers this feature,  though it does not work well because of a slow sensor readout. 

Share this post


Link to post
Share on other sites
3 hours ago, Patrick B. said:

I’m curious why simultaneous dual gain sensor architectures a la the Alexa Alev III aren’t more common in smaller cameras.  This allows a low and high ISO signal to be combined for one HDR image. It seems that in ten years most cameras still can’t match the Alexa for sheer video dynamic range, yet CMOS sensor technology has obviously evolved in many ways.

Is there a limiting factor like size/heat, a patent, or maybe otherwise?  Perhaps it’s just that the average consumer is more interested in increased resolution? We now are seeing the switchable dual gain architecture used more, but I’m not aware of lower end cameras using simultaneous dual gain. 

Related info:

https://www.arri.com/en/learn-help/technology/alev-sensors

 

Certainly in the audio world then the dual A/D converter patent by Zaxcom has been a real roadblock 

Share this post


Link to post
Share on other sites
33 minutes ago, DBounce said:

The Sigma fp will have simultaneous dual gain sensor for HDR. I believe the Z-Cam also offers this feature,  though it does not work well because of a slow sensor readout. 

I think the z cam WDR mode uses two shutter speeds, instead of two gains. Thats why you get strange motion artifacts. It also has dual native ISOs in additionb but no simultaneous dual gain.

Share this post


Link to post
Share on other sites
1 hour ago, IronFilm said:

Certainly in the audio world then the dual A/D converter patent by Zaxcom has been a real roadblock 

Interesting. I’m mainly an audio guy but wasn’t aware of that. 

1 hour ago, KnightsFan said:

I think the z cam WDR mode uses two shutter speeds, instead of two gains. Thats why you get strange motion artifacts. It also has dual native ISOs in additionb but no simultaneous dual gain.

That was my understanding too. It just takes two different exposures in quick succession thus the worse rolling shutter performance.  Doesn’t RED do this too in their special WDR modes?

As opposed to Arri where it seems that both exposures happen together. 

Share this post


Link to post
Share on other sites
35 minutes ago, Patrick B. said:

Interesting. I’m mainly an audio guy but wasn’t aware of that.

That is why the standard version of the Sonosax SX-R4+ can't be sold in the USA! And they had to make a special (read: crippled) version for the USA.

 

Zaxcom patents/lawyers have meddled in lots of other ways too, such as with the Tascam DR10, Audio Ltd A10, or the Lectrosonics PDR, or harassing Newsshooter.com

And we're holding our breath to see if Zaxcom responds legally against the new MixPre Gen 2 or the Zoom F6

Share this post


Link to post
Share on other sites
38 minutes ago, Patrick B. said:

That was my understanding too. It just takes two different exposures in quick succession thus the worse rolling shutter performance.  Doesn’t RED do this too in their special WDR modes?

It's a nitpick, but it's not exactly worse rolling shutter. It's that two shutter speeds are measured simultaneously, so the motion blur isn't natural. It's just like overlaying a shot with 1/48 shutter with a 1/200 shutter; the motion blur is like a "half frame" compared to the rest of the image, because you only get a blur from the 1/48 version.

There is also a Low Noise mode, which uses a longer readout time to get more precision and thus improve noise at the cost of rolling shutter, which doesn't have the motion blur artifact, but does have increased rolling shutter.

13 minutes ago, IronFilm said:

And we're holding our breath to see if Zaxcom responds legally against the new MixPre Gen 2 or the Zoom F6

I was just going to ask how the F6 related to Zaxcom's patents. I wonder if Zoom and/or Sound Devices plans to challenge the patent, like some other companies we talk about a lot here.

Share this post


Link to post
Share on other sites
22 minutes ago, KnightsFan said:

I was just going to ask how the F6 related to Zaxcom's patents. I wonder if Zoom and/or Sound Devices plans to challenge the patent, like some other companies we talk about a lot here.

One of the (many) problems with the patent system is that the patent holder has the full power of the government behind them to enforce it, and if you think their patent is based on bullsh*t then you have a very tough, very expensive, uphill battle to be free of their patent.

So if you're an extremely small and niche company such as Sonosax then it makes no sense at all to even try to fight Zaxcom just to be able to sell your product in one particular market, even if you feel their patent was granted on the most flimsy of reasons. 

Even Tascam, who is a much much much bigger company than Zaxcom, still saw no point in trying to fight it out with Zaxcom because their patent only impact just one product that Tascam makes, which represents but the tiniest fraction of the overall company. Is much easier for them to just tweak the design so the patent can be ignored than to fight the legal case. 

Seems though that one company has finally said enough is enough, and is going to battle it out, when Zaxcom picked a fight with Lectrosonics. Am sure all the other companies are just holding their breath to see how this turns out, if Lectrosonics wins, expect heaps of firmware updates overnight for all the various recording/transmitting products to be fully enabled such as from Audio Ltd and Deity. 

 

Share this post


Link to post
Share on other sites
1 hour ago, KnightsFan said:

It's a nitpick, but it's not exactly worse rolling shutter. It's that two shutter speeds are measured simultaneously, so the motion blur isn't natural. It's just like overlaying a shot with 1/48 shutter with a 1/200 shutter; the motion blur is like a "half frame" compared to the rest of the image, because you only get a blur from the 1/48 version.

Ahh ok that makes sense. 

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...