Smart buffering is something which was first seen on the EOS-D60 and was carried forward with the advent of the EOS 10D. I'm glad to report that it appears as though this method of buffering is also a feature of the EOS 300D, although the EOS 300D has a smaller buffer than the EOS 10D (4 images compared to the 10D's 9 images). The Smart buffering method improves both single shot and continuous drive shooting. The EOS 300D uses its internal buffer for two purposes: buffer the data as it comes from the image sensor (we will call this unprocessed data) and subsequently buffer converted image files before they are written to the CF card. Note that the camera will not write to the CF card unless it is "idle", this means that if you hold the shutter release button in the half-press position the camera will hold the converted image files in the internal buffer until you release.
Image processing sequence:
- Record data as it comes off the image sensor, unprocessed data (approx. 9.3 MB per shot)
- Store this unprocessed data in the SDRAM buffer
- Take unprocessed data and convert into image files (JPEG or compressed RAW)
- Buffer these converted image files (JPEG approx. 3.0 MB or RAW approx. 6.0 MB)
- Write JPEG / RAW image files to CF card
This means that although the buffer can be filled with a continuous burst of four shots it quickly regains buffer space as the unprocessed images are converted into the JPEG or RAW image files. In a real life situation it's easy to believe that the stage 2 runs concurrently to new unprocessed data being buffered.
Take four shots in a continuous burst, keep your finger half-pressed on the shutter release and despite the fact that nothing is being written to the CF card you will see the buffer space indicator fairly quickly count back up again. Remove your finger from the shutter release and the counter doesn't change but you can observe data being written to the CF card (indicator light on the CF compartment door flickers).
Repeating this test for both JPEG Large/Fine and RAW I discovered that the buffer has space (without writing any data to the CF card) for:
- 4 x JPEG Large/Fine images and approx. 2.6 seconds later indicates space to shoot 4 more
- 4 x RAW images and approx. 4.9 seconds later indicates space to shoot 2 more (you must then allow RAW images to be written to CF before any more space is available)
The EOS 300D takes approximately 0.65 sec to convert the unprocessed data into a JPEG Large / Fine file, approximately 2.45 sec to for a compressed RAW file.
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Originally Posted by Geekybiker
