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08-03-2009, 12:44 AM   #1
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K7 Video limit

I have problems with K7 video. In manual I have read about 4GB limit,
but when I have recorded video in 1536x1024 and *** quality , it has ended when reached about 2.5GB! I donīt understand why!

08-03-2009, 04:27 AM   #2
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You need a good class 6 card. I have an "Adata" class 6 card that won't allow me to record more than 28 sec with my K-7, while my "Sandisk" and "Panasonic" allow me to record for the full 4 gb. All cards are not created equal.
08-03-2009, 08:19 AM   #3
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QuoteOriginally posted by therion Quote
but when I have recorded video in 1536x1024 and *** quality , it has ended when reached about 2.5GB! I donīt understand why!
IMHO, it ends at 2GB buffer full when the card isn't fast enough

... or ...

if the projected card full recording time is reached (the remaining time as displayed prior to starting recording). So, on a 4GB card and 70 Mbps projected data rate (cf. user manual), the card is considered full long before it is full (because in practice, data rate is more like 45 Mbps rather than 70 Mbps, depending on the subject). This leads to 2.5 GB max. recording size on a 4 GB card. But never mind, you got the advertized 7 - 8 minutes recording time.

So, to actually obtain a 4 GB file, you need an 8 GB card at least.
08-05-2009, 12:43 AM   #4
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Thanx!

I have bought fastest 8GB Sandisk Extreme III card 30MB/s edition and I will test it!

08-05-2009, 01:23 AM   #5
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I keep reading posts with people asking why their K-7 video recording stopped after 60 seconds......

I can imagine there are going to be many threads on this subject....Class 6 is a minimum read and write speed spec, there are many SDHC cards which just barely meet the minimum, a few which are way faster than that.

For still photo recording, especially single shots, they are probably are all OK, but videos are a different matter.
08-05-2009, 03:12 AM   #6
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I know some of my class 6 8GB cards cannot reach the 4GB record limits. Some of them are so slow that, when the record is stopped, the led busy light is still flashing for the next 10 sec.

When I used my Sandisk Ultra II Class 4 cards, the led busy light stop flashing almost 1 sec after the recording is stopped.

Yes.. not all cards are created equal.
08-05-2009, 03:44 AM   #7
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Some discussion here as well https://www.pentaxforums.com/forums/pentax-dslr-discussion/68915-verbatim-tra...k-7-video.html
08-05-2009, 11:24 AM   #8
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8 GB will record how many minuts ?

08-05-2009, 11:32 AM   #9
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I think in theory 8gb should hold about half on hour of full res video, but in two parts as fat32 FS won't allow files larger than 4gb. This is only a quick calculation.
08-05-2009, 11:40 AM   #10
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QuoteOriginally posted by pasipasi Quote
I think in theory 8gb should hold about half on hour of full res video, but in two parts as fat32 FS won't allow files larger than 4gb. This is only a quick calculation.
Many thanks
08-06-2009, 12:49 PM   #11
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I have tested 8GB Sandisk Ultra III 30MB/sec SDHC kart with my K7 and Iīm not satisfied! In 1536x1024 mode I can record ONLY 7min 36 sec
(about 2.3 GB)!!!

I donīt understand where is the problem! The card should be fast enough!
I hoped I will be able to record about 4GB as it is stated in manual!!!
08-06-2009, 12:50 PM   #12
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I have bought another two cards - Transcend Class6 8GB and problem is the same, just only 2.3GB continuous video :-(((((
08-06-2009, 12:51 PM   #13
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And I have recorded it without sound.
08-06-2009, 12:56 PM   #14
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I use a 16GB Sandisk Extreme III 30mb/sec SDHC and have not yet gone past about 2.5GB but that was my choice not the K-7 . All SDHC cards with FAT32 have a 4GB file limit.
08-06-2009, 04:49 PM   #15
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QuoteOriginally posted by therion Quote
I have tested 8GB Sandisk Ultra III 30MB/sec SDHC kart with my K7 and Iīm not satisfied! In 1536x1024 mode I can record ONLY 7min 36 sec (about 2.3 GB)!!!
I am not sure exactly.

But as I had mentioned earlier, I developed the theory that the K-7 seems to pre-compute the maximum recording length prior to the take.

And despite what I've said earlier, it seems to include the 4 GB file size limit in the calculation.

So, it takes 4 GB (or the remaining free space, whatever is smaller) and it takes the OFFICIAL bitrate to compute the max. recording time.

Which is 7 min. 23 sec. according to page 310 of the K-7 user manual, for 4 GB of free space (74 Mbps, for 1536x1024 mode in 3 star quality).


Now when it does the actual movie recording, the ACTUAL bitrate will be smaller, dependening on available light and the scene (max. bitrate is only used for max. ISO noise and very busy scenes). A typical bitrate is 45 Mbps, resulting in 2.4 GB files.

This doesn't seem to be a bug as asserted recording times (page 310 of the user manual) are met. Only point is that files may turn out smaller than estimated. The footnote on page 310 (marked by 2nd asterisk) doesn't seem to hold true, though. The available recording time is indicated in the movie screen prior to the take as well. Only point is that this time is accurate, not a pessimistic guess.

So, the max. usable time per take seems to be 13 min. 19 sec. (720p in 2 star quality).
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