Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
09-21-2010, 06:57 AM   #1
Site Supporter
jpzk's Avatar

Join Date: Jan 2009
Location: Québec
Photos: Gallery | Albums
Posts: 7,258
The case of the K5 buffer size ... can someone explain?

After much reading in this forum for the K5 specs, and some early tests shown on videos, I came across something which usually doesn't bother me: the buffer size.

I read in some posts that the K5 buffer size is "too small" for the FPS rate ??

Would someone knowledgeable in the matter please explain what this all means?

Don't get me wrong: the more I read about the K5, the more I like it. If the buffer is on par with that of my K7, I don't really care.

Would that affect the way I get my pictures done? Probably not?

Anyway, some thourough explanation of this buffer "issue" would be welcomed.

JP

09-21-2010, 07:10 AM   #2
Veteran Member
RBellavance's Avatar

Join Date: Nov 2006
Location: Near Montréal, Canada
Photos: Gallery
Posts: 1,716
The official specs say that the K-5 can only capture 8 frames at the full 7fps rate in RAW. After that, the rate will slow down because the camera needs to wait for the data to be written to the SD card.

Over on DPReview, there is speculation that this may be an absolute worst-case scenario for scenes at high-ISO and lots of detail, which can't be compressed much. Only real testing will show what the true performance is.

In JPG, the buffer can accept a lot more frames before slowing down.
09-21-2010, 07:33 AM   #3
Site Supporter
jpzk's Avatar

Join Date: Jan 2009
Location: Québec
Photos: Gallery | Albums
Posts: 7,258
Original Poster
QuoteOriginally posted by RBellavance Quote
The official specs say that the K-5 can only capture 8 frames at the full 7fps rate in RAW. After that, the rate will slow down because the camera needs to wait for the data to be written to the SD card.

Over on DPReview, there is speculation that this may be an absolute worst-case scenario for scenes at high-ISO and lots of detail, which can't be compressed much. Only real testing will show what the true performance is.

In JPG, the buffer can accept a lot more frames before slowing down.
Does that mean that, when shooting in RAW, I would get 8 frames in one second but that it would slow down once the buffer is full as you mention?
I don't shoot JPEG.
And, how long would it take for the buffer to empty itself and be ready for another "round"?

Example: Shooting for BIF and pressing the shutter button for 3 seconds, I would then get 8 frames for the first second and much less per second thereafter?
Anyway, better wait for testing.

JP
09-21-2010, 07:41 AM   #4
Veteran Member
RBellavance's Avatar

Join Date: Nov 2006
Location: Near Montréal, Canada
Photos: Gallery
Posts: 1,716
QuoteOriginally posted by jpzk Quote
Does that mean that, when shooting in RAW, I would get 8 frames in one second but that it would slow down once the buffer is full as you mention?
Yes.

QuoteQuote:
And, how long would it take for the buffer to empty itself and be ready for another "round"?
Depends on the card's speed. Note that the camera would not stop altogether after 8 frames, but it would slow down below 7 fps. How much, I don't know. As you write, we'll need to wait for actual performance testing.

09-21-2010, 08:03 AM   #5
Pentaxian
JohnBee's Avatar

Join Date: Sep 2008
Location: front of computer
Posts: 4,620
Does anyone know the actual performance differences between the SDHC and SDxC class cards?
09-21-2010, 08:33 AM   #6
Pentaxian
RonHendriks1966's Avatar

Join Date: Jan 2009
Photos: Gallery
Posts: 8,714
I am wondering too. I read 14 bit RAW instead of our K-7 12 bit Raw. So that does take a lot more work to be done for the PRIME II processor.

If 8 is true, then the buffer is the same as in the K-7 but that is very small.

There is a solution if we can choose if we want 12 bit or 14 bit RAW, because then we have full use of the same buffer as in the K-7 and then we would make 15 or so RAW in one HI continous shooting. With the K-7 that takes about 3 seconds and with the higher framerate from the K-5 it takes just 2 seconds.

I'm holding my breath because just 8 RAW is not good for me.

With full buffer and 14 bit RAW it will take a full second for every new picture to take.
09-21-2010, 10:34 AM   #7
Veteran Member
Eruditass's Avatar

Join Date: Jul 2009
Location: Pittsburgh, PA
Photos: Gallery | Albums
Posts: 2,206
And why have I seen 15 RAW thrown around? what is this shenanigans?
09-21-2010, 10:43 AM   #8
Veteran Member
alexeyga's Avatar

Join Date: Dec 2008
Location: Montreal, Canada
Posts: 838
Some interesting reading from Pentax K-5 Digital Camera - Preview - The Imaging Resource!:

QuoteQuote:
Burst speed. The improvement in burst speed, while perhaps not as big a step forward as that made in terms of sensitivity, is still very worthwhile -- but unfortunately it does come accompanied by a reduction in burst depth. Pentax's previous flagship model, the K-7, offered a maximum of 5.2 frames per second, a figure that was bested a couple of weeks ago with Pentax's announcement that the new mid-range K-r model would offer a class-leading six frames per second. The Pentax K-5 now returns the frame rate crown to the company's new flagship model, with a maximum rate of 7.0 frames per second on offer -- more than one-third faster than the K-7.

At 22 full-resolution Best-quality JPEG frames, the Pentax K5's maximum burst depth has dropped significantly from the K-7's 40 frame limit, and indeed, doesn't quite match the 25-frame limit of the mid-range K-r model. This reduction in depth likely comes as a side effect of the K-5's increased resolution. For raw shooters, the reduction is even more significant, with the Pentax K-5 limited to just 8 raw frames in a Continuous Hi burst -- four less than the K-r, and barely more than half the 15-frame burst depth of the K-7. The harsher penalty in raw shooting is probably further caused by a switch to 14-bit raw files, versus the smaller 12-bit raws created by earlier Pentax DSLRs.

For subjects where a little less speed is required, the K-5's Continuous Lo mode captures Best-quality JPEG images at two frames per second for as long as there's available card space, and can manage 12 Raw frames in a burst. This reduced rate is significantly slower than the 3.3 frames-per-second Continuous Lo burst shooting available in the K-7, and yet is still accompanied by a fair reduction in raw-format burst depth from the K-7's 17 raw frames.
ooops....

09-21-2010, 10:44 AM   #9
Inactive Account




Join Date: Sep 2010
Posts: 34
QuoteQuote:
And why have I seen 15 RAW thrown around? what is this shenanigans?
That's the buffer size of the K-7 which has 5 FPS and captures 12 bit raws. If Pentax had implemented a 12 bit mode on the K-5 (specs mention it captures native 14 bit) and a medium 5 FPS drive mode instead of a stupid low 2 FPS drive mode, then you'd probably get roughly the same amount of buffer. A little would be loss due to the slightly higher resolution of the photos too.
09-21-2010, 12:06 PM   #10
Raylon
Guest




QuoteOriginally posted by jpzk Quote
And, how long would it take for the buffer to empty itself and be ready for another "round"?


JP

If you continue to hold the shutter, it will probably keep shooting at a rate of about 2-4 fps forever, depending on speed memory card. It will take quite a few seconds for all the pictures to them transfer from buffer to memory card. I would have almost preferred a slower fps and the ability to take more pictures in a row.
09-21-2010, 01:57 PM   #11
Veteran Member




Join Date: Jun 2008
Location: NJ
Posts: 1,738
QuoteOriginally posted by alexeyga Quote
Some interesting reading from Pentax K-5 Digital Camera - Preview - The Imaging Resource!:



ooops....
Thanks for the link. Very interesting to see the limits on the new K-5 in burst mode.
09-21-2010, 02:06 PM   #12
Site Supporter
jpzk's Avatar

Join Date: Jan 2009
Location: Québec
Photos: Gallery | Albums
Posts: 7,258
Original Poster
QuoteOriginally posted by RBellavance Quote
Yes.



Depends on the card's speed. Note that the camera would not stop altogether after 8 frames, but it would slow down below 7 fps. How much, I don't know. As you write, we'll need to wait for actual performance testing.
I presently use a Class 10 SDHC card with the K7 and it does take care of business rather well.
Should there be a concern with the buffer of the K5? Not sure at all.
I guess, as you mentioned, that time will tell until we have hands-on tests.
Thanks for replying.

JP
09-21-2010, 02:10 PM   #13
Site Supporter
jpzk's Avatar

Join Date: Jan 2009
Location: Québec
Photos: Gallery | Albums
Posts: 7,258
Original Poster
QuoteOriginally posted by RonHendriks1966 Quote
I am wondering too. I read 14 bit RAW instead of our K-7 12 bit Raw. So that does take a lot more work to be done for the PRIME II processor.

If 8 is true, then the buffer is the same as in the K-7 but that is very small.

There is a solution if we can choose if we want 12 bit or 14 bit RAW, because then we have full use of the same buffer as in the K-7 and then we would make 15 or so RAW in one HI continous shooting. With the K-7 that takes about 3 seconds and with the higher framerate from the K-5 it takes just 2 seconds.

I'm holding my breath because just 8 RAW is not good for me.

With full buffer and 14 bit RAW it will take a full second for every new picture to take.
Ron,

isn't it a fact that 14 bit RAW would be used mostly for "extra" dynamic range?
I may have interpreted someone's post wrongly but that is what I gather from some posts.
I was afraid that it would indeed take a full second to for every new pic, but again this would be in 14 bit. How about in 12 bit?
Anyway, it doesn't really matter until we get some reviews/tests.

JP
09-21-2010, 02:16 PM   #14
Site Supporter
jpzk's Avatar

Join Date: Jan 2009
Location: Québec
Photos: Gallery | Albums
Posts: 7,258
Original Poster
QuoteOriginally posted by alexeyga Quote
Some interesting reading from Pentax K-5 Digital Camera - Preview - The Imaging Resource!:



ooops....
Hmmmm ... this was what I was trying to understand.

In that case, there would seem to be some "loss" of speed while using full burst rate, especially in RAW.
But then, the fact is that the K5 has higher resolution (more Mp's to deal with) and that is an additional "effort" for the processing engine, isn't it?

Would one not choose for higher resolution vs. more frames per seconds ... not sure. I guess it would depend in what situations you use the faster FPS rate and with which format: RAW or JPEG.

Still all jargon to me.

JP
09-21-2010, 02:39 PM   #15
Inactive Account




Join Date: Sep 2010
Posts: 34
QuoteQuote:
isn't it a fact that 14 bit RAW would be used mostly for "extra" dynamic range?
I may have interpreted someone's post wrongly but that is what I gather from some posts.
I was afraid that it would indeed take a full second to for every new pic, but again this would be in 14 bit. How about in 12 bit?
Anyway, it doesn't really matter until we get some reviews/tests.
14 bit isn't extra dynamic range. The dynamic range of a sensor is fixed. How much data you use to record the fixed dynamic range is the bit depth. Essentially on a dark to bright gradient, the dynamic range would show you how far dark and how far bright the camera can faithfully record. The bit depth is how much data this gradient is recorded on. Digital cameras record the gradient in segments. Every level of brightness is ascribed to one segment. There are only so many segments so the full continuous gradient cannot be recorded. Higher bit depth means the camera uses more segments. In essence dynamic range shows the maximum darkness and maximum brightness that can be recorded. Bit depth shows how faithfully everything in between the max darkness and max brightness is recorded.

A camera with low dynamic range but high bit depth will blow out highlights but of the non-blown out highlights, more lighting detail would exist.

A camera with high dynamic range but low bit depth will blow out less highlights but everything will have less lighting detail.

Because the K-5 uses a better sensor with class leading dynamic range, the bit depth had to be increased such that it did not become the limiting factor in recording a good image.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
buffer, camera, dslr, k5, photography, size
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Image Size vs Document Size vs Resolution vs Resampling vs ... AHHHH! veezchick Digital Processing, Software, and Printing 13 08-02-2010 03:57 PM
K7 Buffer Issue? samholton Pentax DSLR Discussion 4 01-08-2010 07:19 AM
Please explain a use case of sensitivity priority dardjiskien Troubleshooting and Beginner Help 9 11-30-2009 10:54 PM
K-7 40 jpeg buffer enough? Pentaxor Pentax DSLR Discussion 5 06-28-2009 01:28 PM
Loving the buffer size - K10D!! photo_mom Pentax DSLR Discussion 27 12-10-2006 06:32 PM



All times are GMT -7. The time now is 01:43 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top