K-5 / K-7 : eight raw buffer limit exists


gubak

Link Posted 24/09/2010 - 10:44
My theory about why the eight raw buffer limit exists (also with an accordingly low JPEG buffer limit) at maximum continuous rate is Pentax's typical conservative specification policy and the existence of these extremely high maximum ISO's in extended ISO mode. To me, it makes sense that the actual raw buffer limit is just proportionally less than that of the K-7 considering the larger pixel dimensions and the faster continuous shooting speed, such that 15 raw captures would seem to be about right for exactly the same shooting environment and ISO sensitivity settings. However, there very well might be only eight raw captures possible for worst case raw files sizes where the maximum raw file size at ISO 51,200 could be as large as 35 MBytes or so.

Thus, there is no discrepancy between the performance of the K-7 and this new K-5 ( as "Which" website says in its video review: http://www.infoborder.com/Digital_Cameras/Video/PentaxK-5.php ), and only confusion about the conditions under which that limit applies.

Anvh

Link Posted 24/09/2010 - 13:46
Why would ISO have influence on the image size, never found a difference between photos shot at ISO 100 or ISO 1600 with the K10D?

I think the the buffer size is smaller because of the more pixels of the K5, the 7 FPS and 14bit instead of 12bit.
Stefan


K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ

timd

Link Posted 24/09/2010 - 13:57
Could it be with that in order to achieve the high ISO, severe processing is required which slows down the process. While RAW does not need to have the JPEG conversion, it probably still has processing in it to get the high ISO...just speculating

Tim

MattMatic

Link Posted 24/09/2010 - 14:02
Just listened the video on PentaxImaging...

The K5 has 14-bit per pixel RAW output, vs the 12-bit per pixel RAW output of the K7 and prior. That, plus the extra pixel count means more RAM usage. I also expect that the K5 firmware is going to use more RAM compared with the K7 - so they've probably got the same SDRAM amounts internally.

14-bit RAW + higher ISO = lovely for me

Matt
http://www.mattmatic.co.uk
(For gallery, tips and links)

Anvh

Link Posted 24/09/2010 - 14:22
timd wrote:
Could it be with that in order to achieve the high ISO, severe processing is required which slows down the process. While RAW does not need to have the JPEG conversion, it probably still has processing in it to get the high ISO...just speculating

Tim

Don't see why?
RAW is just the data from the sensor, so the sensor gives the DATA and the camera simple pack it in a file, so no noise reduction or anything is done by the PRIME II processor.
Stefan


K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ

Anvh

Link Posted 24/09/2010 - 14:27
MattMatic wrote:
The K5 has 14-bit per pixel RAW output, vs the 12-bit per pixel RAW output of the K7 and prior. That, plus the extra pixel count means more RAM usage. I also expect that the K5 firmware is going to use more RAM compared with the K7 - so they've probably got the same SDRAM amounts internally.

Don't forget the 7FPS off the K5 vs the 5.2FPS from the K7 so the buffer fills faster, so with the K7 the camera has more time to process photos while capturing.
I think if you want to fill the buffer the K7 can do maybe 4 images in that time? since the K5 files are larger and the buffer filled faster, I would be surprised if it could do 2 images before the buffer is full.
Stefan


K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
Last Edited by Anvh on 24/09/2010 - 14:28

Smeggypants

Link Posted 25/09/2010 - 01:26
Anvh wrote:
timd wrote:
Could it be with that in order to achieve the high ISO, severe processing is required which slows down the process. While RAW does not need to have the JPEG conversion, it probably still has processing in it to get the high ISO...just speculating

Tim

Don't see why?
RAW is just the data from the sensor, so the sensor gives the DATA and the camera simple pack it in a file, so no noise reduction or anything is done by the PRIME II processor.

What about the processing from the noise reduction algorithms? including the hideous dark frame. The results of these are included in the RAW file. Although the Dark Frame nonsense is proportional to shutter speed.

So yes Higher ISOs could affect processing time.
[i]Bodies: 1x K-5IIs, 2x K-5, Sony TX-5, Nokia 808
Lenses: Pentax DA 10-17mm ED(IF) Fish Eye, Pentax DA 14mm f/2.8, Sigma 17-70mm f/2.8, Pentax-A 28mm f/2.8, Sigma 30mm F1.4 EX DC, Pentax-A 50mm f/1.2, Pentax-A 50mm f/1.4, Pentax-FA 50mm f/1.4, Pentax-A 50mm f/1.7, Pentax DA* 50-135mm f/2.8, Sigma 135-400mm APO DG, and more ..
Flash: AF-540FGZ, Vivitar 283

Anvh

Link Posted 25/09/2010 - 11:08
Smeggypants wrote:
What about the processing from the noise reduction algorithms? including the hideous dark frame. The results of these are included in the RAW file. Although the Dark Frame nonsense is proportional to shutter speed.

So yes Higher ISOs could affect processing time.

Some noise reduction is done in the sensor self but because you're still able to shoot 7fps at ISO 52.000 I don't think that's the problem.
The algorithms for the noise reduction aren't included with the RAW file, have no idea about the DFS though but those only comes on with longer shutter speeds so there is no danger that that will halt the processing of the photo so much that you can fill the buffer.

We aren't talking about processing time but the decrease in the amount photos in the buffer.

You've a K10D and K20D just shoot at highest ISO and tell us your findings.
I already said I couldn't feel a difference.
Stefan


K10D, K5
DA* 16-50, DA* 50-135, D-FA 100 Macro, DA 40 Ltd, DA 18-55
AF-540FGZ
Last Edited by Anvh on 25/09/2010 - 11:09
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