Measuring the performance of DSLR cameras and why the ISO setting could impact the burst length.
Published January 25, 2012 | 
Today arrived the memory card i ordered for my smartphone (16GB Samsung essential micro SD ), so i got curious how it would do in my EOS600D. The speed tests with a card reader are not very representative for the real application, the card could perform good in the card reader but bad in the camera and vice versa. unfortunately, my camera doesn’t have a build in speed test, so I found another way to measure the real performance. The solution is to record the shutter sound!
I used the mic of the Logitech webcam (my usb microscope :) and Audacity (Free, Cross-Platform Sound Editor) for recording and analysis.
The results of different memory cards are not surprising, but i also tried different camera settings and was astonished about the significant burst rate drop on higher ISOs. The following tests are done in manual mode with manual focus and all the same settings with exception of ISO.
As you can see, the burst length is getting shorter with rising ISO. The time camera needs to write the buffer to the card is also significantly grown. The reason is the noise. On higher ISO settings we getting more noise in picture and noisy pictures are not good for compression. The RAW-File size (black picture shouted with closed lens cap) varies from 19MB @ ISO100 to 32MB @ ISO12800.
Also interesting is the comparsion of burst speed shooting in RAW versus JPEG. While the burst length with JPEG files is virtually infinite (with fast sd-card), the burst speed is slightly lower.
RAW vs JPEG
And the finally comparsion between different memory cards in this order: SanDisk Extreme HD Video, Hama 150x, Samsung Essential MicroSDHC, SanDisk ultra II
A bit surprising is the fact, that Hama performs better than Samsung :)
I think it’s the best method to measure the performance of the memory card you buying for your camera. Unfortunately I don’t have faster cards (like SanDisk Extreme Pro), I’m really curious if the 600D can use this high speed cards with full transfer rate.
Did you turn off high iso noise reduction? This might account for the drop in speed based on higher isos.
The noise reduction was off. But anyway, there is no noise reduction if you shooting raw ;)
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This is really interesting. Saw this on DIYP. I use Audacity a fair bit too on Linux – grat application.
The slower JPEG speed is probably atributable to the post-RAW processing that goes on in-camera to process the RAW image to a jpeg, then compress the image – all done on the fly, whereas RAW is straight out of the sensor and onto the card.
You can probably burst RAW faster but will fill the buffer faster due to the much larger size, or have a slightly slower burst rate but sustain it for longer as the buffer won’t fill as fast, but the images are smaller so get written to the card faster and the buffer clears faster and so the buffer takes longer to completely fill.
Did you turn of RAW compression and compare the speed?
*turn off
How? Is it possible at all?
I know nothing about cameras. But the fact that noise in the same size images would create a different file size indicates that some compression is happening. A true raw file will always be the same size regardless of what is contained in the data.
As far I know, compression used in raw, is lossless. So, after decompression, you getting the true raw ;)
I know it’s possible on my Nikon D300; it’s buried along with the bit depth of the raw. No idea if it’s possible on Canons
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You actually make it seem so easy with your presentation but I
find this topic to be actually something which I think I would
never understand. It seems too complicated and very
broad for me. I’m looking forward for your next post, I’ll try to get the hang of it!