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 Post subject: Re: A99 shutter cycle - can owners pleae help me with a test
Unread postPosted: Sat Dec 08, 2012 5:24 am 
Tower of Babel
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When it comes to memory cards there is a potential bottleneck with SD cards, SDHC has a transfer speed of only 10 or 12 Mbytes/sec, SDXC has improved the transfer speed greatly to around 100Mbytes/sec but there is the gotcha that those are all formatted in ExFat which is fine if you are using Vista or Win7-8 and is also compatible with three Mac OS’s, but not so good if you are using anything else, and there might be a question mark on A99 compatibility as well, it hasn’t been identified just where the problem is in the case of that camera.
I was reasonably happy with the 16bit interface of CF memory and its reliable error free transfer and speed of up to 165 Mbytes/sec (in the latest version).
When it comes to Sony and SLT’s, I think it’s probably a good idea to have them in the range but where is the traditional DSLR just for those who want only that and no flim flam.
Greg


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 Post subject: Re: A99 shutter cycle - can owners pleae help me with a test
Unread postPosted: Sat Dec 08, 2012 8:02 am 
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Greg, modern SDHC may be much faster, the SDXC spec is more about the file system.

The real problem is that pushing a given max throughput with 4bit interface requires four times more power compared to 8bit and then another x4 to 16bit. And most cam bodies limit the write speed exactly by power consumption and not by max card speed. And that's why the MS HX are faster with the SLT/Nex.

P.S. Actually I made a factual mistake above - it's only twice more power for twice less bit-width. Four times per bit line, but twice less lines. But increasing throughput x2 means increasing consumption x4 for a given interface.


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 Post subject: Re: A99 shutter cycle - can owners pleae help me with a test
Unread postPosted: Sun Dec 09, 2012 12:07 am 
Tower of Babel
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Could be agorabasta, could be, it’s just that mostly you see the transfer speed for SDHC quoted in Mbits/sec not Mbytes/sec to make it seem like a lot when it isn’t. And yes power consumption nearly doubles on that interface to get performance (4bit-8bit, 1.8v – 3.3v) from what I read, and then from what I’ve come to know in the past when you do that there is always the risk of capacitance getting in the works, the inbuilt controller on the card has to do a lot of extra error checking and erase-rewrites to prevent files getting scruffed up, (and they have been on the SDXC cards for reasons yet to be established) and then the buffer in the camera gets backed up and becomes choked and the whole thing grinds to a halt. Most likely the high speed card never gets out of first gear (1.8v) anyway to conserve power; the host device sets the power consumption it wants the memory system to use.
But hey we should all rejoice, the whole interface for SD-USB is cheaper than that for CF-SATA and cheap is what we all crave…right? Who needs reliable 16Bit bandwidth LBA memory transfer when you can have cheap instead?
The next evolution (according to Wiki) for CF was going to be PCI-Express interfaced but Sony switched to SD cards at about that point and it never materialized, well not in A-mount anyway.
I think SD memory is just another reason to not buy a Sony camera that has it and the reasons are plentiful enough already with the other things they fixed that weren’t broken, and the collateral damage didn’t get much attention either.
Greg
Ps Btw I’m sure I read somewhere that CF uses 5v and draws 500ma so that’s not too bad if the bandwidth is four times that of SD, but it’s probably more the current it uses rather than the voltage that affects the battery.


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 Post subject: Re: A99 shutter cycle - can owners pleae help me with a test
Unread postPosted: Sun Dec 09, 2012 2:46 am 
Subsuming Vortex of Brilliance
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Thing about SD is it's universal. Got a MS reader on your laptop? Probably not but you will have an SD one!
Want to use your memory card in a compact/bridge type camera? Bingo just go right ahead.

MS died years ago Sony had to wake up that making MS cameras was hurting their sales. CF is fine I have enough for the 2 5d's I have.
As for speed USH-I is pretty fast, if I had any criticism of SD it was that they should have seen ahead a while back with speed and compatibility. This was not a problem for CF. I just don't see a place for MS anymore. Even class 10 SD cards are probably fast enough for most. I'm not buying the MS sales take here because Sony make products which compete with rivals. D600 has a 15 shot buffer, 17 with the D800, 5d MkIII is about 17 shots (14bit raw I think for those) A99 has 13 lowest of all the models.

Now I'm not much of a fps shooter anyway but I note this. Canon's 650d has a lousy buffer of just 6 frames (despite 5fps) probably to save the 60d for action shooters. D7k has a buffer of 10 shots v the 11 of the D90 (bit odd really) K-r had a pretty good buffer of 13/14 shots.
For a camera in the A99's price bracket I'd expect a buffer a bit bigger just slap 20 shot raw buffer on the entire range can't be that hard to do..and what happened to that no flapping mirror high fps rate? 6fps is pretty fast but you'd expect more for an SLT camera surely?


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 Post subject: Re: A99 shutter cycle - can owners pleae help me with a test
Unread postPosted: Sun Dec 09, 2012 3:14 am 
Tower of Babel
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The problem as I see it is the huge sensors and file sizes in most cameras, that’s what produces the supposedly small buffers with around 2 seconds of shooting to fill up I think, that and the bottleneck at the memory interface. I think to extend the shooting time you would have to have two CF cards operating in tandem to keep clearing the buffer, either that or make sensors with a more sensible file size of around 10 or 12MP for action shooting. The A99 has that ability of course but still has the dubious memory interface of SD or MS, I’m not sure if anyone has conducted any tests on how fast and long the A99 can shoot with the truncated shutter action in crop mode, everyone seems to think that 10MP is too small to take a decent photo these days, when it isn’t of course.
Greg


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 Post subject: Re: A99 shutter cycle - can owners pleae help me with a test
Unread postPosted: Mon Dec 10, 2012 7:12 pm 
Emperor of a Minor Galaxy
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As file sizes and FPS get larger, they go from a 16 bit CF card to a 4 bit SD card.

This like the the highway planners who put a 2 lane bridge over the river on a 6 lane highway.

Dusty

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 Post subject: Re: A99 shutter cycle - can owners pleae help me with a test
Unread postPosted: Tue Dec 11, 2012 12:13 am 
Subsuming Vortex of Brilliance
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Like CF or not (and I'm fine with it) the SD thing is done and dusted
I still think if you've a decent enough buffer to start with you'll be just fine. I have class 10 SD cards and they're ok for what I do.
I don't think you can make up a small buffer even with very fast cards I tried a UHS-I card in the D7k ok got a few more frames in but with a 10 shot ish buffer you won't get much more. If you had a 20 shot odd buffer across the range of SLT models very few folks would be complaining.

Work the buffer that's my view. Maybe the A99's buffer is "ok" for people time will tell. I don't often hit the buffer anyway the Km5d has 5/6 shots in raw and sure for action you will even jpeg, K-x was around the same buffer hit that a few times. Anything 9-10 and up raw for me is generally safe enough. That 20 frame A57 buffer goes pretty quick if you're shooting raw and at the silly fast fps.

I'm surprised some of these cameras don't have massive buffers you would think they'd shove a 30/40 shot raw buffer in the full frame models and just forget about it :mrgreen:


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 Post subject: Re: A99 shutter cycle - can owners pleae help me with a test
Unread postPosted: Tue Dec 11, 2012 3:18 pm 
Tower of Babel
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I think the problem would only escalate if you increase the buffer size, if you had a larger buffer the camera at the highest frame rate is still going to fill it up if the bandwidth at the memory interface can’t keep up, then you have to wait correspondingly longer for it to clear, meanwhile you are stuck with a camera that can’t take any photos while that is happening.
The problem is caused by shooting in those huge file sizes at a high frame rate first and foremost and then by the memory bandwidth in the second place, that’s assuming part of the hold up isn’t processing. Of course if you use the camera sensibly I doubt you would have any buffer problems even with the SD potential choke point.
Greg


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 Post subject: Re: A99 shutter cycle - can owners pleae help me with a test
Unread postPosted: Wed Dec 12, 2012 2:09 pm 
Imperial Ambassador
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Dusty wrote:
As file sizes and FPS get larger, they go from a 16 bit CF card to a 4 bit SD card.

This like the the highway planners who put a 2 lane bridge over the river on a 6 lane highway.

Dusty


I love that analogy, superb.
Just like the planners here in Scotland. They build a gazillion houses in an area but leave the single track road for access.

Mike

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 Post subject: Re: A99 shutter cycle - can owners pleae help me with a test
Unread postPosted: Wed Dec 12, 2012 11:38 pm 
Subsuming Vortex of Brilliance
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Evidently the A77 is UHS-1 Compliant not sure about the other models. Those cards are pretty fast..I usually buy class 10 as they're fast enough. And not all are the same either. Most of the SD cards I have are as fast as the CF ones I use, which are erm fast enough!


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