90D RAW only burst count

Started 2 months ago | Questions thread
DavidArmenPhoto Regular Member • Posts: 343

RLight wrote:

DavidArmenPhoto wrote:

RLight wrote:

I ran into the same thing; all isn’t as it appears...


I’ve read your post before. Correct me if I’m wrong, but don’t your conclusions show that every single one of the UHS-II cards you tested performed at at least double the speed of the fastest UHS-I SD card currently on market (Sandisk Extrme Pro)?

If, using AI-Servo (slightly slower FPS) and C-RAW, yes.

If, you're using Single Shot (faster FPS) and RAW, you deplete your buffer so fast, it's virtually no different.

IR did a writeup on RAW vs C-RAW, have a peek...


For best buffer, UHS-II and C-RAW is advised.

Ohh so you are saying that the 10fps burst fills up the buffer so fast that the SD card has barely transferred a couple of photos by the time buffer is full? That makes sense.

Although if we get into theory: say if the 10fps burst lasts 3 seconds (regardless of file size), and your UHS-I has a write speed of 80MB/s whereas your UHS-II card has a write speed of 240MB/s and the buffer begins unloading to the card immediately once you start taking the burst, then by the end of that 3-second burst, you’ve unloaded:

80MB/s * 3sec = 240MB for UHS-I vs

240MB/s * 3sec = 720MB for UHS-II

I would think that that extra 480MB that was written to the UHS-II SD card during the burst would result in the ability to take more shots in that burst before the buffer is full and the write speed can’t keep up with uploading it fast enough. I assume this is not what happens in real life. Maybe the buffer begins to unload to the SD card 2-3 seconds after you press the shutter? That would negate any speed difference between the cards since they would only begin to be written to at the end of the burst period.
However, I would still highly recommend UHS-II cards for the 90D especially for sports and wildlife shooters because although that initial burst fills the buffer very quickly, that buffer will be able to unload to the SD card at a rate almost 3 times faster after you depress the shutter, so you will be able to shoot 10-20-30 frame Busts at a faster rate since it will unload at 1/3 of the time of a UHS-I card. Am I wrong to assume this?

And thanks for the c-raw info link, I’ve been wanting to do some research on it since I’m totally new to cr3 raw files. I never need to adjust exposure more than one stop up or down and I heard that I will see almost no negative difference in my case if I move to c-raw.

 DavidArmenPhoto's gear list:DavidArmenPhoto's gear list
Canon EOS 90D Canon EF 85mm f/1.8 USM Sigma 50mm F1.4 EX DG HSM Sigma 30mm F1.4 EX DC HSM Sigma 17-50mm F2.8 EX DC OS HSM +3 more
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