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Archive 2012 · burst speed and buffer depth - Is it affected by file size?

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p.1 #1 · p.1 #1 · burst speed and buffer depth - Is it affected by file size?

I am well aware that shooting in jpeg (versus raw) allows for a much deeper buffer and longer sustained burst shooting, but is it also affected by file size? I.e. does shooting in raw (small) instead of raw (large) yield a deeper buffer and a longer sustained burst? One would think so, as less data needs to be written to the card with a smaller resolution raw file, but I also know that things aren't always so simple, and that filesize of the resulting file may not be the limiting factor here.

Any thoughts or experiences? I shoot a 7D and that is mainly what I am interested in knowing about, but relevant information or experience with other models would also be helpful!


Nov 16, 2012 at 03:41 PM
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p.1 #2 · p.1 #2 · burst speed and buffer depth - Is it affected by file size?

Interestingly enough, if I remember correctly, a large jpg can be slower than raw because the processor has to convert it, where the raw just goes straight to the card.


Nov 16, 2012 at 04:58 PM
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p.1 #3 · p.1 #3 · burst speed and buffer depth - Is it affected by file size?

You would think so, but not necessarily. The 7D had an odd behavior before the latest firmware update when shooting RAW+jpg. The buffer was always limited to 7, and that didn't change even if you used sRAW+low rez jpg.

As Paul noted, some of that was probably the conversion to jpg, but you'd still think that the huge difference in file sizes would have some effect.

In that case, it seemed like it was more a firmware limitation than an actual processing speed issue. And the dramatic increase in RAW+jpg buffer from the new firmware seems to bear that out.

I think you'll just have to play with it. The buffer size in the viewfinder should give you a pretty good idea.


Nov 16, 2012 at 05:10 PM
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p.1 #4 · p.1 #4 · burst speed and buffer depth - Is it affected by file size?

Shooting the 7D before and after the firmware change I can say its a real difference.
Before I only shot raw as the 6 or 7 shot limit for raw+jpeg was a real pain. Anyway since the upgrade its almost a non issue.

But there are also things you have to take into consideration when thinking buffer.

Card speed, while there is a nominal max buffer (see how many you get without a card in the slot) a fast card (as long as the camera can use all the speed) will squeeze a couple of extra shots from the buffer over a slow card. Think of the buffer like a bucket with a hole in it. A larger hole will stop the bucket filling up so quick.

File size. Most modern cameras can almost go on forever when set to large jpeg. But raw files are much bigger and the camera still has to produce a jpeg for each (the embedded one you see on the preview) . I've not shot any of the smaller raw files to see if the buffer is different but I think I did notice the number in the viewfinder was different when I had it in mraw By mistake onceA while back , (pre fw2.0)

The thing is now on the 7D the buffer for large raw and a decent card is over 20 shots (over 3 seconds burst time) and when it's full the slow down is not that great (this is where the fast card helps a lot as well) so I really can't see that much point in shooting mraw . And you can also help yourself a fair bit by shooting in bursts that don't totally fill the buffer. If you shoot in 1.5-2 seconds bursts even with a very small pause in between you can stretch things quite a bit.

Nov 16, 2012 at 09:27 PM

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