Home · Register · Join Upload & Sell

Moderated by: Fred Miranda
Username  

  New fredmiranda.com Mobile Site
  New Feature: SMS Notification alert
  New Feature: Buy & Sell Watchlist
  

FM Forums | Canon Forum | Join Upload & Sell

1       2       3      
4
       5       6       end
  

Archive 2013 · Speed test with CF cards

  
 
Sven Jeppesen
Offline
• • • •
Upload & Sell: Off
p.4 #1 · p.4 #1 · Speed test with CF cards


:


But the buffer is not full 30 seconds! That's what you calculated



May 11, 2013 at 01:51 AM
Lars Johnsson
Offline
• • • • • • •
Upload & Sell: Off
p.4 #2 · p.4 #2 · Speed test with CF cards


RichFisher wrote:
Assumption: 1Dx buffer is 30 frames. Camera starts writing after the 1st shot and continues writing through the 30 second test. At the end of the test the buffer is full and the camera has written the number of shots Lars recorded less 30 which are still in the buffer.

I then calculated how fast the camera can shoot when the buffer is full.

For example in the case of the Lexar 1000x card, the initial 30 shots filled the buffer. The next 130 (160-30) shots occurred as the buffer was emptied. For every shot taken, one had to be written to
...Show more


Rich, you have to change a few things in your math to get it right,

1. The buffer is not 30 frames.
2. The buffer takes a lot longer to get full with a fast card compared to a slow card. So it's not the same number at all for all those cards.
3. If you like to calculate how fast the camera can shoot when the buffer is full. Then you can't use your 30 seconds. The buffer is empty when I start. That figure would more likely be something like 23 to 28 depending on what card you use.



May 11, 2013 at 02:24 AM
Lars Johnsson
Offline
• • • • • • •
Upload & Sell: Off
p.4 #3 · p.4 #3 · Speed test with CF cards


RichFisher wrote:
My tests on the Lexar 1000x and Sandisk Extreme Pro (both 32GB) indicate the same thing. There was not a large difference between them.


IMO there is a big difference between the Lexar 1000x and the Sandisk Extreme Pro UDMA 6 cards that you own.



May 11, 2013 at 03:07 AM
Lars Johnsson
Offline
• • • • • • •
Upload & Sell: Off
p.4 #4 · p.4 #4 · Speed test with CF cards


Gunzorro wrote:
Thanks, Lars! I try to keep up on what is current, as well as what applies to the older gear -- it's a lot to remember. So far, you have been right on memory cards and a lot of other gear. We all appreciate your sharing your test results and experience.



Jim, thanks a lot

Lars



May 11, 2013 at 03:08 AM
Lars Johnsson
Offline
• • • • • • •
Upload & Sell: Off
p.4 #5 · p.4 #5 · Speed test with CF cards


RichFisher wrote:
Different label - wonder if they are any faster once inside a 1Dx? I can get a burst of ~50 shots with either the Lexar 1000x or Extreme Pro (UDMA 6) card before it noticeably slows done.


Shoot when the buffer is full with both cards. Then you will see the difference.



May 11, 2013 at 03:10 AM
Lars Johnsson
Offline
• • • • • • •
Upload & Sell: Off
p.4 #6 · p.4 #6 · Speed test with CF cards


gdanmitchell wrote:
Now we're talking. That is useful information for those who feel they need the ability to shoot very long bursts. How fast will the rate be before filling the buffer (in most cases, the specs tell us roughly) and once the buffer fills what will the rate drop to.

Dan


The math and figures was wrong. But I suppose you didn't care so much about that



May 11, 2013 at 03:13 AM
Lars Johnsson
Offline
• • • • • • •
Upload & Sell: Off
p.4 #7 · p.4 #7 · Speed test with CF cards


RobertLynn wrote:
I think this post is awesome, and it showcases some great numbers for people who need to know what card/how many shots they can get in relation to the speed of the card.
Thanks Lars!



Thanks Robert, appreciate it

Lars



May 11, 2013 at 03:14 AM
Lars Johnsson
Offline
• • • • • • •
Upload & Sell: Off
p.4 #8 · p.4 #8 · Speed test with CF cards


RichFisher wrote:
Glad to help. I guess the high school algebra is useful after all

The after buffer is full is the information I value most. Before the buffer is full, I will get 12 FPS with any card, but after that cards matter.


Cards matter before the buffer is full also. With a very slow card maybe you get 25-30 pics before the buffer is full. With a fast card maybe you get 55-65 pics before the buffer is full.
Yes you get 12fp/s with any card. With a very slow card you only get that for 2-3 seconds. With a fast card you get 12fp/s for 5-7 seconds. That's a huge difference when shooting sport or wildlife



May 11, 2013 at 03:18 AM
Lars Johnsson
Offline
• • • • • • •
Upload & Sell: Off
p.4 #9 · p.4 #9 · Speed test with CF cards


Sven Jeppesen wrote:
But the buffer is not full 30 seconds! That's what you calculated


You are right about that Sven.



May 11, 2013 at 03:23 AM
RichFisher
Offline
• • •
Upload & Sell: On
p.4 #10 · p.4 #10 · Speed test with CF cards


Lars Johnsson wrote:
The math and figures was wrong. But I suppose you didn't care so much about that


Yes the math is precisely wrong but general correct and correct enough to allow a reasonable comparison between cards.

Here is details of the model

At the start of the 30 second test period, Lars pushes the shutter (or cable release). Then 1/12th of a second later (0.083333 seconds or 83 milliseconds) the shutter is closed and the data starts transferring to the buffer. Let's assume that the transfer from the sensor to the buffer occurs instantaneously (not true but close enough) and the shutter curtain starts to reset and data starts to transfer out of the buffer to the card.

This repeats again and again and again. Data is written to the buffer faster than it can be written to the card, so the buffer slowly fills up. Eventually the buffer fills up, so the camera waits for the next image to be written to the card before capturing the next image. This is when we see the camera slow down. Initially the the camera's buffer is being filled, but once full it remains full for the duration of the test. This creates a quasi-steady state. If the buffer was not full, the camera would revert to 12 fps which would fill it quickly.

So what happens? During the 30 second test, all but buffer full of images are written to the card. Key question is how big is the buffer? Hard to tell - Canon compresses raw files. But 30 is a good estimate - could be 28 or 32. The exact size of the buffer will only effect the absolute rate at which images are written to the card, not the relative speed. And there are other factors which also effect this, such as the file size. Raw files are not fixed size, rather they vary depending upon how well Canon's compression can reduce their size.

Glad to discuss this further. Let me know if you have any additional questions.

Edited on May 12, 2013 at 12:37 AM · View previous versions



May 11, 2013 at 11:59 PM
RichFisher
Offline
• • •
Upload & Sell: On
p.4 #11 · p.4 #11 · Speed test with CF cards


Lars Johnsson wrote:
You are right about that Sven.



The buffer is not full initial, but once the camera fps slows done, it remains full (see previous discuss on the details of the model). If the buffer was not full, the camera would begin recording images at 12 fps until the buffer was full.



May 12, 2013 at 12:00 AM
RichFisher
Offline
• • •
Upload & Sell: On
p.4 #12 · p.4 #12 · Speed test with CF cards


Lars Johnsson wrote:
Cards matter before the buffer is full also. With a very slow card maybe you get 25-30 pics before the buffer is full. With a fast card maybe you get 55-65 pics before the buffer is full.
Yes you get 12fp/s with any card. With a very slow card you only get that for 2-3 seconds. With a fast card you get 12fp/s for 5-7 seconds. That's a huge difference when shooting sport or wildlife


True, because the camera can write to the card will being filled



May 12, 2013 at 12:02 AM
RichFisher
Offline
• • •
Upload & Sell: On
p.4 #13 · p.4 #13 · Speed test with CF cards


Sven Jeppesen wrote:
But the buffer is not full 30 seconds! That's what you calculated



Only care that the buffer is full at the end.



May 12, 2013 at 12:04 AM
Lars Johnsson
Offline
• • • • • • •
Upload & Sell: Off
p.4 #14 · p.4 #14 · Speed test with CF cards


RichFisher wrote:
The buffer is not full initial, but once the camera fps slows done, it remains full (see previous discuss on the details of the model). If the buffer was not full, the camera would begin recording images at 12 fps until the buffer was full.


I'm not sure you get it
You wrote that you "calculated how fast the camera can shoot when the buffer is full"

But that's not what you did in your calculation. You start from the beginning and then calculate with 30 seconds. And the buffer was not full 30 seconds.
The result you got is a nice addon for the test. But it does not show how fast the camera can shoot when the buffer is full.



May 12, 2013 at 02:26 AM
gdanmitchell
Offline
• • • • • • •
Upload & Sell: Off
p.4 #15 · p.4 #15 · Speed test with CF cards


Lars Johnsson wrote:
The math and figures was wrong. But I suppose you didn't care so much about that


I think that perhaps I should have written "That would be useful information..."

I hereby stand corrected.

Note on snarky comment: I care a great deal about facts and I pay attention to them and what they imply. That's why I like the idea of understanding the facts about how the "normal" burst rate and post-buffer-fill burst rate measure. I don't believe that, aside from not noting the errors in another person's post, I have said anything factually incorrect or suggested that I don't care about "the math and figures."

Have fun.

Dan



May 12, 2013 at 07:11 PM
RichFisher
Offline
• • •
Upload & Sell: On
p.4 #16 · p.4 #16 · Speed test with CF cards


Lars Johnsson wrote:
I'm not sure you get it
You wrote that you "calculated how fast the camera can shoot when the buffer is full"

But that's not what you did in your calculation. You start from the beginning and then calculate with 30 seconds. And the buffer was not full 30 seconds.
The result you got is a nice addon for the test. But it does not show how fast the camera can shoot when the buffer is full.


Yes I get it.

What I calculated is how fast the buffer empties (using a number of approximations, all of which are reasonable, and will not have a significant impact upon the final result). Since I have every reason to believe that the buffer empties at the same rate regardless of the number of images it holds, whether it 1 image or is maxed out, the rate calculated is the rate that buffer empties when the card is full and hence how fast the camera can shoot when the buffer is full.



May 12, 2013 at 10:37 PM
Lars Johnsson
Offline
• • • • • • •
Upload & Sell: Off
p.4 #17 · p.4 #17 · Speed test with CF cards


I don't belive your approximations are reasonable. And some of the things you assume I did in my test are also wrong. You have not been reading in my link how I actually did it. Especially this one have faults:

"Assumption: 1Dx buffer is 30 frames. Camera starts writing after the 1st shot and continues writing through the 30 second test. At the end of the test the buffer is full and the camera has written the number of shots Lars recorded less 30 which are still in the buffer.
I then calculated how fast the camera can shoot when the buffer is full."



May 13, 2013 at 12:05 AM
lighthawk
Offline
• • •
Upload & Sell: Off
p.4 #18 · p.4 #18 · Speed test with CF cards


Lars Johnsson wrote:
Thanks Stan, that's a good point about being able to shoot forever at 4fps with a fast card

Lars


I rarely outrun my buffer, but it has happened. Recently, I wanted to experiment with time lapse, shooting 1 FPS on Canon 6D. My 400x card stalled, and the camera had to wait while writing to card.



May 13, 2013 at 12:26 AM
jxsq
Offline
• • •
Upload & Sell: Off
p.4 #19 · p.4 #19 · Speed test with CF cards


In amazon page for 1000x card
http://www.amazon.com/Transcend-Information-32GB-Compact-flash/dp/B009S61AHE

David Stewart state that their low level formating tools makes huge difference, I am not sure if this is the case here too?


Did you ever try their level formatting tools?

Thanks


Lars Johnsson wrote:
The difference you pointed out is very big. I'm also surprised by that. But you could actually talk about good and bad copies of the cards , just like lenses here. Those cards that I have many copies of will also give me a little bit different result depending on what copy I used.
Most times the larger card will be a little bit faster than the smaller card when shooting with the same kind of cards.
With these two cards and such a large difference. I belive some of it is has to do with the fact that the
...Show more



May 19, 2013 at 11:47 AM
jxsq
Offline
• • •
Upload & Sell: Off
p.4 #20 · p.4 #20 · Speed test with CF cards


Just download transcend's autoformat tool and tried on my 400x UDMA card

http://www.pbase.com/jxsq/image/150277389/original.jpg

It almost get 4 more shots (RAW) before it slow down, even though after that the speed is about same. (which I cannot explain)




May 19, 2013 at 01:25 PM
1       2       3      
4
       5       6       end




FM Forums | Canon Forum | Join Upload & Sell

1       2       3      
4
       5       6       end
    
 

You are not logged in. Login or Register

Username       Or Reset password



This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.