Same Sensor, different dynamic range and base ISO?

[eyrie_algebra]

As far as I know, all of these cameras used the same IMX461 102MP Sony sensor from 2018. I am wondering what has been tweaked in each of these sensors to give different base ISO and slightly improved dynamic range.

Camera (year): Base ISO / PDR / RN / FWC / EDR

• GFX 100 (2019): 100 | 12.24 | 3.411 | 41,534 | 13.6
• HB X2D (2022): 64 | 12.32 | 2.250 | 34,682 | 13.9
• GFX 100 II (2023): 80 | 12.55 | 2.514 | 53,625 | 14.4
• HB X2D II (2025): 50 | ? | ? | ? | ?

These data are from photonstophotos. From my understanding, the changes are

From GFX 100 to GFX 100 II,

• Larger FWC leads to lower base ISO - 100/(53,625/41,534) = 80,
• Larger FWC leads to better EDR on higher end - log_2(53,625/41,534) = 0.369
• Lower Read Noise leads to log_2(3.411/2.514) = 0.440 better EDR on lower end.

From GFX 100 to X2D,

• Lower FWC lead to -log_2(34,682/41,534) = 0.260 worse EDR on the higher end
• But the better read noise lead to log_2(3.411/2.250) = 0.600 better EDR
• To produce an image with same lightness from the same exposure, the GFX should be log_2(34,682/41,534)=0.26 stops more sensitive. (Not really sure here, correct me if wrong)

QUESTIONS:

1. How did the camera manufacturers tweak the same sensor to give different FWC?
2. Do we know what has changed, on the pixel level, between these cameras that to give different read noise?
3. Why is the base ISO of X2D not 100/(34,682/41,534) = 120? I suppose this is just because the ISO are calibrated differently?
4. Could we estimate the FWC of X2D II by taking 64/50 x 34,682 if we assume the ISO are calibrated the same way? Thus, the increase in FWC of EDR the log_2(64/50) = 0.356? Note that Hasselblad claims an increase of 0.3 stop of DR from X2D to X2Dii.

 

[SrMi]

As far as I know, all of these cameras used the same IMX461 102MP Sony sensor from 2018. I am wondering what has been tweaked in each of these sensors to give different base ISO and slightly improved dynamic range.

Camera (year): Base ISO / PDR / RN / FWC / EDR

• GFX 100 (2019): 100 | 12.24 | 3.411 | 41,534 | 13.6
• HB X2D (2022): 64 | 12.32 | 2.250 | 34,682 | 13.9
• GFX 100 II (2023): 80 | 12.55 | 2.514 | 53,625 | 14.4
• HB X2D II (2025): 50 | ? | ? | ? | ?

These data are from photonstophotos. From my understanding, the changes are

From GFX 100 to GFX 100 II,

• Larger FWC leads to lower base ISO - 100/(53,625/41,534) = 80,
• Larger FWC leads to better EDR on higher end - log_2(53,625/41,534) = 0.369
• Lower Read Noise leads to log_2(3.411/2.514) = 0.440 better EDR on lower end.

The reason for the GFZ 100 II ISO 80 unusually good read noise - the last word

This is the 22nd post in a series of tests of the Fujifilm GFX 100, Mark II. You can find all the posts in this series by going to the Categories pane in the right hand panel and clicking on “GFX 100 II”. I normally do dark-field histograms first when I test cameras. With the

blog.kasson.com

From GFX 100 to X2D,

• Lower FWC lead to -log_2(34,682/41,534) = 0.260 worse EDR on the higher end
• But the better read noise lead to log_2(3.411/2.250) = 0.600 better EDR
• To produce an image with same lightness from the same exposure, the GFX should be log_2(34,682/41,534)=0.26 stops more sensitive. (Not really sure here, correct me if wrong)

QUESTIONS:

1. How did the camera manufacturers tweak the same sensor to give different FWC?
2. Do we know what has changed, on the pixel level, between these cameras that to give different read noise?
3. Why is the base ISO of X2D not 100/(34,682/41,534) = 120? I suppose this is just because the ISO are calibrated differently?
4. Could we estimate the FWC of X2D II by taking 64/50 x 34,682 if we assume the ISO are calibrated the same way? Thus, the increase in FWC of EDR the log_2(64/50) = 0.356? Note that Hasselblad claims an increase of 0.3 stop of DR from X2D to X2Dii.

 

[JimKasson]

As far as I know, all of these cameras used the same IMX461 102MP Sony sensor from 2018. I am wondering what has been tweaked in each of these sensors to give different base ISO and slightly improved dynamic range.

Camera (year): Base ISO / PDR / RN / FWC / EDR

• GFX 100 (2019): 100 | 12.24 | 3.411 | 41,534 | 13.6
• HB X2D (2022): 64 | 12.32 | 2.250 | 34,682 | 13.9
• GFX 100 II (2023): 80 | 12.55 | 2.514 | 53,625 | 14.4
• HB X2D II (2025): 50 | ? | ? | ? | ?

These data are from photonstophotos. From my understanding, the changes are

From GFX 100 to GFX 100 II,

• Larger FWC leads to lower base ISO - 100/(53,625/41,534) = 80,
• Larger FWC leads to better EDR on higher end - log_2(53,625/41,534) = 0.369
• Lower Read Noise leads to log_2(3.411/2.514) = 0.440 better EDR on lower end.

Lower read noise is due to in-camera black point subtraction at ISO 80.

From GFX 100 to X2D,

• Lower FWC lead to -log_2(34,682/41,534) = 0.260 worse EDR on the higher end
• But the better read noise lead to log_2(3.411/2.250) = 0.600 better EDR
• To produce an image with same lightness from the same exposure, the GFX should be log_2(34,682/41,534)=0.26 stops more sensitive. (Not really sure here, correct me if wrong)

QUESTIONS:

1. How did the camera manufacturers tweak the same sensor to give different FWC?

They are not varying the FWC per se, but the clipping point of the ADC.

1. Do we know what has changed, on the pixel level, between these cameras that to give different read noise?

See above.

1. Why is the base ISO of X2D not 100/(34,682/41,534) = 120? I suppose this is just because the ISO are calibrated differently?

Base ISO specification affords the camera manufacturer a lot of wiggle room.

1. Could we estimate the FWC of X2D II by taking 64/50 x 34,682 if we assume the ISO are calibrated the same way? Thus, the increase in FWC of EDR the log_2(64/50) = 0.356? Note that Hasselblad claims an increase of 0.3 stop of DR from X2D to X2Dii.

Wait for test results.

 

[CCD1024]

Hello

If we take the sensor itself, not inside a consumer cameras, there are several ways to run it.

There are at least 4 modes to operate the IMAX461 (and 411)

Consumer cameras usualy use photgraphic mode with the amplifier switch at 400 iso. It is possible to operate the sensor at lower readout noise or higher dynamic range or better FWC.

Difficulty of the sensor is the lowest ISO (gain) even extended like 40 iso but often it is not a real mode.

Some manufacturers can choose any mode or switch from one to another one depending of what they think the best for image. No rules.



Example of modes used on astronmy cameras with IMX461 :













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