K-3: actual buffer write speed compared

Started 5 months ago | Discussions
beholder3
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K-3: actual buffer write speed compared
5 months ago

Hi,

about the buffer write speed of the K-3 here some real data:

Test setup:

The tests were non scientific and just to compare relatively. Fire away RAW DNGs with manual focus in hi speed and measure the time beginning at when the frequency gets slower (since the buffer is full) until the red writing LED stops. Yes, that doesnt take into account that during the first 2-3 seconds already some data is written, but that applies to all cards.

K-5 reference:

The K-5 series was able to write the full buffer of RAW files (usually around 22-25 pictures) with around 540 MB data within 30 seconds after the buffer was shot full with hi speed series.

The very fastest ones we tested (34 different ones) were about 27 seconds with about 21,8 MB/sec.

K-3:

We only have data for 5 different models here but the best one writes the full 24Mpx buffer in 16 seconds. That is quite a major  write speed increase even while having to write 50% larger files. That is somwhere between 35 and 40 MB/sec.

For those who don't believe it: http://www.youtube.com/watch?v=uQNossi-pnY

With other cards writing the buffer takes about 27 seconds (same overall time as K-5) for  50% more data, meaning about 30 MB/sec.

Pentax K-3 Pentax K-5
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emem
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Interesting info ...........
In reply to beholder3, 5 months ago

............. can you name "... the best ones ..." ?

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Mike McEnaney. (emem)
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beholder3
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SanDisk Extreme 64GB 80MB/s UHS-I (SDSDXS-064G-X46)
In reply to emem, 5 months ago

emem wrote:

............. can you name "... the best ones ..." ?

I guess it's easiest if you let google translate this thread here: http://www.dslr-forum.de/showthread.php?t=1346884 as it has the full info.

In the youtube comment the card is named: SanDisk Extreme 64GB 80MB/s UHS-I (SDSDXS-064G-X46)

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Kerusker
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Re: SanDisk Extreme 64GB 80MB/s UHS-I (SDSDXS-064G-X46)
In reply to beholder3, 5 months ago

beholder3 wrote:

emem wrote:

............. can you name "... the best ones ..." ?

I guess it's easiest if you let google translate this thread here: http://www.dslr-forum.de/showthread.php?t=1346884 as it has the full info.

In the youtube comment the card is named: SanDisk Extreme 64GB 80MB/s UHS-I (SDSDXS-064G-X46)

Thanks for the test.

Did the test include a SanDisk Extreme Pro 95MB/s (read speed; or any other with 95MB/s like Sony)?

There is a extensive test also:

http://www.valuetech.de/blog/reviews-foto/2013/02/10/sdhc-test-2013

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][.Kerusker
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emem
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Re: SanDisk Extreme 64GB 80MB/s UHS-I (SDSDXS-064G-X46)
In reply to beholder3, 5 months ago

beholder3 wrote:

emem wrote:

............. can you name "... the best ones ..." ?

I guess it's easiest if you let google translate this thread here: http://www.dslr-forum.de/showthread.php?t=1346884 as it has the full info.

In the youtube comment the card is named: SanDisk Extreme 64GB 80MB/s UHS-I (SDSDXS-064G-X46)

Thanks - appreciate the info. I'm just about to invest in a few cards.

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Mike McEnaney. (emem)
www.veritasmea.com

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James O'Neill
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Re: K-3: actual buffer write speed compared
In reply to beholder3, 5 months ago

beholder3 wrote:

Hi,

about the buffer write speed of the K-3 here some real data:

Test setup:

The tests were non scientific and just to compare relatively. Fire away RAW DNGs with manual focus in hi speed and measure the time beginning at when the frequency gets slower (since the buffer is full) until the red writing LED stops. Yes, that doesnt take into account that during the first 2-3 seconds already some data is written, but that applies to all cards.

K-5 reference:

The K-5 series was able to write the full buffer of RAW files (usually around 22-25 pictures) with around 540 MB data within 30 seconds after the buffer was shot full with hi speed series.

The very fastest ones we tested (34 different ones) were about 27 seconds with about 21,8 MB/sec.

K-3:

We only have data for 5 different models here but the best one writes the full 24Mpx buffer in 16 seconds. That is quite a major write speed increase even while having to write 50% larger files. That is somwhere between 35 and 40 MB/sec.

For those who don't believe it: http://www.youtube.com/watch?v=uQNossi-pnY

With other cards writing the buffer takes about 27 seconds (same overall time as K-5) for 50% more data, meaning about 30 MB/sec.

I worked out the following and posted it to an earlier thread

[Pentax Specs give these speeds]
- Continuous H: Approx 8.3 FPS (60 JPG, 23 RAW)
- Continuous M: Approx 4.5 FPS (100 JPG, 32 RAW)
- Continuous L: Approx 3.0 FPS (200 JPG, 52 RAW)

I'm assuming a raw file is 30MB - based on 14 bit raw / 16MP being 20MB in the K5 So 14 bit /24MP should be 50% bigger so.

23 Raw Frames @ 8.3 FPS = ~ 690 MB in 2.77 sec
32 Raw Frames @ 4.5 FPS = ~ 960 MB in 7.111 sec
52 Raw Frames @ 3 FPS = ~ 1560 MB in 17.33sec

So if the slower frame rate allows an extra 870MB in 14.5 seconds that's 59.74 MB/second of data going off to the card. In 2.77 seconds it would write out 165MB of data, leaving the buffer as 524MB. Call it 512MB i.e. 1/2GB

The numbers in the spec seem to assume a 60MB/sec card.

My back-of-an evelope sums say 24 frames in 16 seconds is ~ 45MB/sec

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beholder3
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Re: K-3: actual buffer write speed compared
In reply to James O'Neill, 5 months ago

My PNY card does 24 RAWs at Hi, 32 at medium, 49 at slow speeds before the card slows things down to 1,5 FPS.

This assumes all corrections are turned off on no slow card is present in the other slot.

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James O'Neill
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Re: K-3: actual buffer write speed compared
In reply to beholder3, 5 months ago

beholder3 wrote:

My PNY card does 24 RAWs at Hi, 32 at medium, 49 at slow speeds before the card slows things down to 1,5 FPS.

And how big are the files ?

If it does 24 @ 8.3 fps that's 2.9 seconds

If does 32 @ 4.5 that's 7.1 seconds.  So in the extra 4.2 secs it wrote an extra 8 frames.

If it does 49 @ 3 ftps that's 16.3 seconds so in the 13.4 compared with high speed it wrote an extra 25 frames., and in the extra 9.2 compared with medium speed it wrote 17 frames. It's just a we bit slower than 2 frames worth of data per second. If you're seeing 1.5 fps sustained once the buffer is full that is in the right area. So how many bytes per frame ?  Also what ever number of frames the camera maintains with a full buffer x bytes per frame is the write speed.

Now if in 2.9 seconds it took to shoot 24 frames at high speed the camera wrote between 5 and 6 photos there's space in the buffer for 18/19 frames. I make this roughly 1/2 GB of buffer.

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yudi
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Re: SanDisk Extreme 64GB 80MB/s UHS-I (SDSDXS-064G-X46)
In reply to beholder3, 5 months ago

very useful information and good reference. thanks for the tests!

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