5D3 buffer burst rate

Hi gang,

Checking to see what is the expected normal for the buffer size. As I understand, the buffer is the main "speed control" for continued bursts. It tells you how many shots you can take in the viewfinder.

What I observed is that if I have the camera on:
1. auto iso, LRAW, LJPG Fine, I get [6]
2. iso 100, LRAW, JJPG Fine, I get [7]
3. auto iso, LJPG Fine, I get [35]

Your secondary speed comes from the compact flash speed in order to clear that buffer. I haven't tried a long stream of bursts, wanted to understand how the primary buffer should work first of all. In case it matters, I have a 64GB Lexar 1066x installed.

Is that what is expected?

Canon has an excellent write up at http://www.learn.usa.c​anon.com …tanding_burst_r​ates.htmlp on "burst" and "buffer". Well worth a read.

I have also found a good way of testing things is to photograph a watch with at least a second hand, more if you have something digital and then look at the EXIF and do the math as needed based on the time logged in the EXIF.

John from PA wrote in post #17121118
Canon has an excellent write up at http://www.learn.usa.c​anon.com …tanding_burst_r​ates.htmlp on "burst" and "buffer". Well worth a read.

I have also found a good way of testing things is to photograph a watch with at least a second hand, more if you have something digital and then look at the EXIF and do the math as needed based on the time logged in the EXIF.

thanks for that. from that site:

Approx. 65 JPEG (CF)
Approx. 13 RAW (CF)

how do I hit 13 raw?

a_dee wrote in post #17121229
thanks for that. from that site:

Approx. 65 JPEG (CF)
Approx. 13 RAW (CF)

how do I hit 13 raw?

Maybe write just RAW to CF and turn off all in-camera processing of images?

a_dee wrote in post #17121229
thanks for that. from that site:

Approx. 65 JPEG (CF)
Approx. 13 RAW (CF)

how do I hit 13 raw?

turn off JPEG as well, therefore only write RAWs.

Are you writing to both the CF and the SD card?

The SD card slot is slow as heck. If you write only to the CF card, your speeds should increase. Using a Sandisk 60mb/s card and shooting RAW, I've never run into the full buffer when doing 6fps bursts.

tagnal wrote in post #17121273
Are you writing to both the CF and the SD card?

The SD card slot is slow as heck. If you write only to the CF card, your speeds should increase. Using a Sandisk 60mb/s card and shooting RAW, I've never run into the full buffer when doing 6fps bursts.

Nope, there's a card in there, but not being used, just set to 'automatically switch' setting.

KCY wrote in post #17121262
turn off JPEG as well, therefore only write RAWs.

I did try that, just can't remember now what I got when it was just raw alone.

a_dee wrote in post #17121278
I did try that, just can't remember now what I got when it was just raw alone.

i just checked mine, at ISO100 i get 13 in the display, at H2 i get 9

KCY wrote in post #17121291
i just checked mine, at ISO100 i get 13 in the display, at H2 i get 9

That's set to LRAW alone? What's H2? (pardon my ignorance).

H2 is expanded ISO settings, so very high iso.

i just did some further digging, some very interesting results
all at ISO100
RAW - 13
MRAW - 9
SRAW - 12

KCY wrote in post #17121300
H2 is expanded ISO settings, so very high iso.

i just did some further digging, some very interesting results
all at ISO100
RAW - 13
MRAW - 9
SRAW - 12

yah, I remember seeing MRAW being lower than you would expect due to file size.

KCY wrote in post #17121300
H2 is expanded ISO settings, so very high iso.

i just did some further digging, some very interesting results
all at ISO100
RAW - 13
MRAW - 9
SRAW - 12

I think this can be explained by observing that sRAW is exactly 1/4 of the number of pixels of a full RAW. So 4 pixels combine their values into one. Easy calculation for the camera.

mRAW, on the other hand, has to do more complex equations to get half the resolution, so more processing power is needed.

But I'm just guessing.

With raw and jpeg the number of shots it will show drops considerably. It will usually hold 13 shots in the buffer when shooting large raw, this could change slightly depending on the size of the files of course, so ISO and subject will have an effect.

However, that isn't the maximum burst, which will be higher. I find that I typically get 17-18 shots at the maximum frame rate, using a 400x card. This is because the buffer starts clearing to the card as soon as the first shot is taken, so in the 2 seconds it takes to shoot those 13 shots it will have written 4 to the card and made space for 4 more, and it will clear another while shooting those 4.

So, I get 17 or 18 shots at the full speed, then the buffer is full. The camera doesn't stop shooting though, it just continues to shoot at about 2 fps, and it can keep that up indefinitely until the card is full.

That is at 400x, your card is 1066x so will empty the buffer even quicker. If my 400x can clear the buffer at two shots per second, yours should be able to clear it almost as fast as the camera shoots, so your actual burst could be several dozen shots before the buffer fills, and even then it will only slow down a little. However, it is hard to be certain just from the rating as some cards ratings aren't always accurate for comparisons.

sandpiper wrote in post #17121358
That is at 400x, your card is 1066x so will empty the buffer even quicker.

Depending on the write speed of the camera. I'd be amazed if it could write that fast.