p.5 #1 · Sony A9III CFE-a Memory Card Performance Data
snapsy wrote:
You wrote the data indicates a "simple two sequential buffer model", then commented how it sometimes causes a break and sometimes does not, then commented how the model indicates it should. The data then does not fit the conclusion about the model.
I did not say that a simple two sequential buffer model was "indicated". My comment was to the point that a simple model does not work! "sometimes it does not, even though in a simple model it should".
I have not drawn any conclusions. In fact I have been consistently skeptical that anyone has offered a model that explains all the observations and have been more than skeptical about people that take memory card specs as an indication of how the camera will perform. I believe I have been consistent in stating that I only believe the data, not the theories. I believe the comments by @Daran and @j4nu have been interesting and reasonable and they have been appropriately hedged.
This debate is not interesting or useful. I am going to Torrey Pines to see what the Peregrines are doing.
p.5 #2 · Sony A9III CFE-a Memory Card Performance Data
The publicly available sensor datasheets provide all the information one needs to establish a good working model of how this all works. When formulating theories it's best to start with the available documentation and work backwards rather than speculating from data observations alone.
For example, here's a screenshot of the datasheet for the stacked sensor that likely shares the same design as the A9:
"On-Chip DRAM function is available by readout data into DRAM using fast 12-parallel ADC prior to output still pictures via SLVS-EC to reduce readout-time of each frame"
To decode that, the data is read off the sensor in parallel 12-rows at a time and deposited into the fast stacked memory colocated on the sensor complex. There is no logic on the sensor to perform any of the image processing steps that have been speculated in this thread. All those operations are the sole domain of the image ASIC, which for Sony cameras is named BIONZ. Since the datasheet clearly describes how the data is deposited into memory, the subsequent image processing steps performed are then performed on that memory. That memory area is the "buffer".
p.5 #3 · Sony A9III CFE-a Memory Card Performance Data
Fascinating thread that I'd missed before I started a new post. All I can add is that I found in trying to do panning shots with the a9iii that it can actually hit 30fps with a 1/30s shutter speed provided that the camera is set to 60fps or 120fps. If the camera is just set to 30fps it gets around 15fps at 1/30s.
This is a solution to an issue I ran into with the Z8/Z9 when I found that those cameras couldn't hit 20fps until 1/250s shutter. Similarly, when I shot the A1 I found that it also hit around 15fps at 1/30s. The a9iii also hits this limitation unless the camera is in H+. Then, it will hit as many frames as the shutter speed will allow up to 120fps.
p.5 #4 · Sony A9III CFE-a Memory Card Performance Data
UKBob wrote:
Shuttermuse has an interesting article about the best card for an A9iii and he recommends one with the highest sustained write speed ie the ProDigital Gold Type A card with a sustained write speed of 600mb/secBest memory cards for the A9iii -I was wrong
Can I ask what capacity cards would be recommended for an exciting day of wildlife action and how do you configure slots 1 and 2
For the A1 I use 160gb Sony card in Slot 1 with compressed RAW and 80gb in slot 2 for JPEG as back up which gives about 2200 images for each slot However I sort through the images each day and have never run out of space on the 160gb card with my shooting style which is short bursts ...Show more →
I just read his article and decided to give the ProGrade Gold 480gb cards a go. It's not cheap, but when you start looking at the smaller capacity cards, you're paying way more per gb.
Pergear has a 520gb card that has--according to them--sustained write speeds up to 900mb/s, but the min write speed is stated at 400mb/s, which seems like a big range. But they're pretty cheap. I may try them for the hell of it.
However, to your point, on my A1, I used 160gb and 260gb cards and never ran out of space on a day of shooting. Granted, I'm usually not actually shooting all day (I wish I could) and I'm pretty selective on what I'm shooting in bursts.
I'm guessing the A9iii is a totally different ball game when the key feature is all about speed. I'll curios to know if my shooting style/habits change with the A9iii, which I'm waiting delivery on.
p.5 #5 · Sony A9III CFE-a Memory Card Performance Data
dclark wrote:
This data raises some interesting questions about how the sensor/camera/memory electronics works. The most obvious question is the one raised by @randomguy@, why does the buffer not fill and slow the frame rate to 5 FPS when running at 30 FPS or slower? In order to make this more clear I have added a couple of lines to the frames vs time chart. It seems that the buffer that can hold ~236 frames empties at a rate of 5 FPS when data is coming in at a rate of 120 FPS or 60 FPS, but empties at a rate of ~13 FPS when data is coming in at 30 FPS or slower. Consequently at 30 FPS the buffer does not fill at ~9.3 sec with ~280 frames but fills at ~13.5 sec and 406 frames.
There is also another buffer that fills when running at 120 FPS or 60 FPS. It has a capacity of ~156 frames and empties at a rate of ~22 FPS. When running at 30 FPS or slower it never fills. That buffer is first in the data flow.
Since Sony does not share any details with us we are left to speculate about exactly how the electronics works. But at least we can measure what the result is in terms of how data flows at various camera frame rates. ...Show more →
I still can't wrap my head around why a setting of 120fps will result in a 5fps steady state while a setting of 30fps will result in a 13fps steady state. If the guess is that 120fps setting means the sensor is scanned and maybe even processed at that rate no matter how full the buffer is, and only 5fps is saved to the card, (which means 115fps are eventually discarded), that seems to be serious firmware bug. Seems to me the correct way of doing things should be to not scan/process the sensor data (other than for EVF purpose) until there is room to move the data off the sensor.
p.5 #6 · Sony A9III CFE-a Memory Card Performance Data
dclark wrote:
There is only one processor. If it's busy responding to interrupts from data coming in, it does not have much time to transfer frames from the buffer to the card. It seems that when the buffer is full the sensor electronics is still trying to send files at the full rate of 120/60fps and consequently occupying the processor with frames that get dropped. That may also be part of the explanation why the frame intervals are so non-uniform.
For desktop processors, since 1998 we have had DMA which allows data transfer to happen without disturbing the CPU.
Idk what’s used on the camera, but it’s pretty lame not having DMA in 2024
p.5 #7 · Sony A9III CFE-a Memory Card Performance Data
snapsy wrote:
The data is moved off the sensor and into a buffer. The image processing steps are then performed on that buffer via the imaging ASIC. When those steps are complete the buffer is written to media and then recycled to be used for another frame.
Different buffers.
Image is read from the sensor into a very fast buffer where (some) processing is done. This buffer might hold multiple frames with a pipeline moving the image along. When finished it goes into a much bigger buffer that holds frames waiting to be written to the card. The much bigger buffer could be slower RAM than the one/s used for image processing.
p.5 #8 · Sony A9III CFE-a Memory Card Performance Data
Tony Ross wrote:
Different buffers.
Image is read from the sensor into a very fast buffer where (some) processing is done. This buffer might hold multiple frames with a pipeline moving the image along. When finished it goes into a much bigger buffer that holds frames waiting to be written to the card. The much bigger buffer could be slower RAM than the one/s used for image processing.
p.5 #9 · Sony A9III CFE-a Memory Card Performance Data
jhapeman wrote:
120fps even with a bigger buffer is a tough use case because of the sheer number of photos you have to slog through. I mostly use my A9III at 30fps with precapture. I used 120fps when I was trying to capture hummingbirds in flight or similar things where the incredibly fast action also calls for an incredibly fast frame rate but you most certainly have to train your brain and finger to work differently in these cases.
For something like your example of the osprey, hitting the shutter right at the moment it is hitting the water is probably ideal if you have a decent-sized recapture turned on. ...Show more →
The camera does let you lock the frames you want, then delete the rest of the burst.
p.5 #10 · Sony A9III CFE-a Memory Card Performance Data
Hodie wrote:
I just read his article and decided to give the ProGrade Gold 480gb cards a go. It's not cheap, but when you start looking at the smaller capacity cards, you're paying way more per gb.
Pergear has a 520gb card that has--according to them--sustained write speeds up to 900mb/s, but the min write speed is stated at 400mb/s, which seems like a big range. But they're pretty cheap. I may try them for the hell of it.
However, to your point, on my A1, I used 160gb and 260gb cards and never ran out of space on a day of shooting. Granted, I'm usually not actually shooting all day (I wish I could) and I'm pretty selective on what I'm shooting in bursts.
I'm guessing the A9iii is a totally different ball game when the key feature is all about speed. I'll curios to know if my shooting style/habits change with the A9iii, which I'm waiting delivery on....Show more →
CF-A gen 3 can theoretically write at 1000MB/s. We may benefit from cards capable of 1000MB/s sustained, which the gen4 cards can do.
p.5 #11 · Sony A9III CFE-a Memory Card Performance Data
dclark wrote:
In order for a CFE-a type 4 memory card (i.e. a card with a PCIe-4 data lane) to provide any improvement, the camera would need to have PCIe-4 electronics, not PCIE-3 electronics.
So far as we know there are no Sony cameras with a PCIe-4 data lane, but we can't be certain about the A9III.
Someone needs to put a type 4 card in an A9III and make the measurements.
I will be surprised if it is faster, but pleasantly surprised.
Perhaps, the NAND on a type 4 card could be faster?.
CF Express 2.0 is supposed to support 1GB/s transfers, but according to your tests we are not getting that.
