dclark wrote: speedmaster20d wrote: dclark wrote: speedmaster20d wrote:
the fan test does not support the theory of groups with large phase offset for either A7R5 or A7R6. However it doesn't provide ANY insight about the detailed row / col timing diagram of the sensor. There could still be groups with very small offset. I no longer have the vintage A9 to see how it would have looked like.
I really don't want to speculate on this, there are correct ways of measuring the exact sensor timings down to sub micro-seconds but it requires using some specialized assets... I can't use my current setup to measure beyond readout time , maybe some day I will....
you can also see the difference between the readout times between the two cameras
Your 1:1 photos show that the readout is 1 row at a time. If there were 12 rows it would show up clearly. Even the guessed and speculated 4 or more would be easily seen.
I think so, or let say most likely.... but even when the rows are grouped they are still scanned in staggered fashion, the stagger delay can be micro second range, the groups on the other hand can have large offset which would create the kind of staircase you mention ( which this test rules out obviously ) but they can also have very small offset that is not visible.... there are commercial examples of each....so I am not certain 100% but as far as effect in the photos are concerned I am with you to call it rolling.
It does not matter if they are digitized at different times, it only matters when charge transfer to the sense node is triggered. I suppose there may be some variation by row that is difficult to detect in the image, but if it's difficult to detect in measurements like this, it is unimportant so far as rolling shutter distortion is concerned. If we can't see it in test images meant to show it, who cares? BTW, the appearance of the staircase in the A9 is shown in my post from a few years ago that is linked earlier in this thread.
yes the conversion (digitization) time does not matter , it is decoupled from charge transfer from the photo cells.
in a generic image sensor ( I don't claim to know any specific details about Sony and even if I knew I wouldn't disclose here )
- the row to row rolling stagger delay is to let each (long) row's voltage initialize and settle before the charge transfer gates can open. after the gate opens , charge is shared and we have to wait again for the critical voltages to settle before we move on to the next row.
- sometimes these rows are grouped together so that they can share initialization and settle time, but it requires stronger source drivers and can increase power. if you zoom into the group there is a little bit of staggering of rows still but could be small.
- There could be time offset between these groups, the offset can be large or small depending on how many source drivers you have and other design details....
measuring this detail timing require disassembling the camera and probing certain traces with an oscilloscope while still driving the image sensor with an FPGA copying the camera's logic. There could be some creative ways to guesstimate it by an optical setup .... but honestly who has the time and motivation to do it and as you say if it doesn't show up in a photograph why care ?
I have no clue what exactly Sony does but it could be that in their current cameras they use mostly a rolling scheme and it could be that in the A9 that had a different scheme that resulted in those staircases artifacts.
----------
sorry bit of tangent above - we can focus back on the photographic aspect.
I think we can say for photographic purposes all these cameras are using rolling scan with no such thing as `4 or 8 or 12' rows and I also measured the readout times so we got all that we really care about already
what I plan to do with these readout times is make a table and estimate what panning conditions are problematic and then give this camera a final verdict.
Edit : I went back and looked at my A9 II files, I can see the same kind of artifact Dave had found... never seen this on 300K worth of A1 and A1 II files
dclark wrote: speedmaster20d wrote: dclark wrote: speedmaster20d wrote:
the fan test does not support the theory of groups with large phase offset for either A7R5 or A7R6. However it doesn't provide ANY insight about the detailed row / col timing diagram of the sensor. There could still be groups with very small offset. I no longer have the vintage A9 to see how it would have looked like.
I really don't want to speculate on this, there are correct ways of measuring the exact sensor timings down to sub micro-seconds but it requires using some specialized assets... I can't use my current setup to measure beyond readout time , maybe some day I will....
you can also see the difference between the readout times between the two cameras
Your 1:1 photos show that the readout is 1 row at a time. If there were 12 rows it would show up clearly. Even the guessed and speculated 4 or more would be easily seen.
I think so, or let say most likely.... but even when the rows are grouped they are still scanned in staggered fashion, the stagger delay can be micro second range, the groups on the other hand can have large offset which would create the kind of staircase you mention ( which this test rules out obviously ) but they can also have very small offset that is not visible.... there are commercial examples of each....so I am not certain 100% but as far as effect in the photos are concerned I am with you to call it rolling.
It does not matter if they are digitized at different times, it only matters when charge transfer to the sense node is triggered. I suppose there may be some variation by row that is difficult to detect in the image, but if it's difficult to detect in measurements like this, it is unimportant so far as rolling shutter distortion is concerned. If we can't see it in test images meant to show it, who cares? BTW, the appearance of the staircase in the A9 is shown in my post from a few years ago that is linked earlier in this thread.
yes the conversion (digitization) time does not matter , it is decoupled from charge transfer from the photo cells.
in a generic image sensor ( I don't claim to know any specific details about Sony and even if I knew I wouldn't disclose here )
- the row to row rolling stagger delay is to let each (long) row's voltage initialize and settle before the charge transfer gates can open. after the gate opens , charge is shared and we have to wait again for the critical voltages to settle before we move on to the next row.
- sometimes these rows are grouped together so that they can share initialization and settle time, but it requires stronger source drivers and can increase power. if you zoom into the group there is a little bit of staggering of rows still but could be small.
- There could be time offset between these groups, the offset can be large or small depending on how many source drivers you have and other design details....
measuring this detail timing require disassembling the camera and probing certain traces with an oscilloscope while still driving the image sensor with an FPGA copying the camera's logic. There could be some creative ways to guesstimate it by an optical setup .... but honestly who has the time and motivation to do it and as you say if it doesn't show up in a photograph why care ?
I have no clue what exactly Sony does but it could be that in their current cameras they use mostly a rolling scheme and it could be that in the A9 that had a different scheme that resulted in those staircases artifacts.
----------
sorry bit of tangent above - we can focus back on the photographic aspect.
I think we can say for photographic purposes all these cameras are using rolling scan with no such thing as `4 or 8 or 12' rows and I also measured the readout times so we got all that we really care about already
what I plan to do with these readout times is make a table and estimate what panning conditions are problematic and then give this camera a final verdict.
but as far as effect in the photos are concerned I am with you to call it rolling. 