Canon EOS 20DBy: Shawn Barnett and Dave EtchellsSlightly smaller and lighter upgrade brings greater speed and ease of use along with higher res and lower image noise. <<Exposure & Flash :(Previous) | (Next): Operation & User Interface>> Page 8:Shutter Lag & Cycle Time TestsReview First Posted: 08/19/2004, Update: 11/19/2004 |
Shutter Lag & Cycle Time Tests
When you press the shutter release on a camera, there's usually a lag time or delay before the shutter actually fires. This corresponds to the time required for the autofocus and autoexposure mechanisms time to do their work, and can amount to a fairly long delay in some situations. Since this number is rarely reported on (and even more rarely reported accurately), and can significantly affect the picture taking experience, I routinely measure both shutter delay and shot to shot cycle times for all cameras I test, using a test system I designed and built for the purpose. (Crystal-controlled, with a resolution of 0.001 second.) Here are the numbers I collected for the Canon EOS 20D. (These were initially collected with a prototype sample, and subsequently verified with a production model. The only change I found was in buffer depth, the production unit can grab up to 31 large/fine JPEGs without pausing, whereas the prototype I tested was limited to 23. All other performance numbers were right in line with what I found on the prototype sample.):
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(secs) |
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| Power On -> First shot | |
So fast
it's hard to measure accurately. Your reflexes will be the reason you
miss any shots, not the camera's startup speed. |
| Shutdown | |
First
time is simple shutdown, second time is worst-case buffer-clearing time.
(After a sequence of 6 RAW+JPEG images in continuous mode.) |
| Play to Record, first shot | |
So fast
it's difficult to measure. |
| Record to play | |
First
time is that required to display a large/fine file immediately after
capture, second time is that needed to display a large/fine file that
has already been processed and stored on the memory card. First time
is fast, but not astonishingly so, second time is so fast that you really
won't notice any delay. |
| Shutter lag, full autofocus | |
Times with the kit lens. (18-55mm) First time is at full wide-angle, second is full telephoto. Very fast. |
| Shutter lag, prefocus | |
Time to
capture, after half-pressing shutter button. Very fast, if not quite
the 65 milliseconds of the Canon spec. |
| Shutter lag, manual focus | |
Fast but
not amazingly so. Still, 0.1 second is faster than most photographer's
reaction time. |
| Cycle Time, Single frame mode LF JPG Lexar 1GB 80x CF card |
0.48 / 1.27 (2.1 / 0.79 fps) |
First number is cycle time before buffer fills, second number is after buffer fills. Times are averages. Buffer filled after 21 shots of a target designed to be difficult to compress, and takes 19 seconds to empty completely with a Lexar 80x CF card. Very fast, the post-buffer-fill cycle time is quite impressive as well. |
| Cycle Time Single frame mode RAW + LF JPG Lexar 1GB 80x CF card |
0.43 / 3.8 (2.3 / 0.26 fps) |
First number is cycle time before buffer fills, second number is after buffer fills. Times are averages. Buffer fills after 6 shots and takes 24 seconds to empty with an 80x Lexar CF card. (After the 6th shot, the cycle time degrades gradually, with roughly 1.1 seconds till the 7th shot, then 2.5 seconds to the 8th, before finally settling into 3.8 seconds/shot for the long haul.) |
| Cycle Time Continuous mode LF JPG Lexar 1GB 80x CF card |
0.21 / 1.13 (4.8 / 0.89 fps) |
First number is cycle time before buffer fills, second number is after buffer fills. Times are averages. Buffer fills after 31 shots of a low-compressibility target and takes 19 seconds to empty with the Lexar 80x CF card. |
| Cycle Time Continuous mode LF JPG SanDisk Extreme 1GB CF card |
0.21 / 0.81 (4.8 / 1.24 fps) |
First number is cycle time before buffer fills, second number is after buffer fills. Times are averages. Buffer fills after 21 shots of a low-compressibility target and takes 12 seconds to empty. While both the Lexar 80x and SanDisk Extreme cards are very fast in the camera, the SanDisk Extreme has a slight edge in throughput. |
| Cycle Time Continuous mode RAW + LF JPG Lexar 1GB 80x CF card |
0.21 / 3.35 (4.8 / 0.30 fps) |
First number is cycle time before buffer fills, second number is after buffer fills. Times are averages. Buffer fills after 6 shots and takes 24 seconds to empty. Image compressibility doesn't affect timing significantly, and buffer capacity is always 6 shots in RAW+JPEG mode. (The 20D shows a similar "gradual fill" timing characteristic in RAW+JPEG mode when shooting continuously as was mentioned in the single-shot commentary above.) |
| Cycle Time Continuous mode RAW + LF JPG SanDisk Extreme 1GB CF card |
0.21 / 2.35 (4.8 / 0.43 fps) |
First number is cycle time before buffer fills, second number is after buffer fills. Times are averages. Buffer fills after 6 shots and takes 16 seconds to empty. Again, the SanDisk Extreme has an edge in buffer-clear times. |
Without a doubt, the EOS 20D is an impressively fast camera, all the more
so given its 8.2 megapixel imager. (That's a lot of data to sling around
that quickly.) Shutter lag is better than that of the earlier 10D, the Digital
Rebel, or the Nikon D70, in many cases significantly so. Cycle times are also
very impressive, whether in single-shot or continuous mode. Buffer capacity
for JPEG images is excellent: Using a low-compressibility color-noise image
as the subject, we consistently shot 31 large/fine JPEGs (depending on subject
detail) before having to wait for the card to catch up; and at about a second
per image, post-buffer-fill cycle time was excellent as well. Shooting in
RAW+JPEG mode cuts buffer capacity to 6 frames, regardless of the subject
matter or JPEG quality setting, and slows both the post-buffer-fill cycle
time and buffer recovery rate as well. - But the cycle time for those first
6 frames is still very good, and you don't have to wait for the buffer to
clear entirely before shooting another series.
From a practical standpoint, while the 20D doesn't approach the speed of the 1D Mark II, the combination of 5 frames/second and a JPEG buffer depth of 31 frames (or 6 frames for RAW+JPEG shooters) makes a huge impact on the sense of speed and responsiveness we felt with the camera, compared to the lower-end Rebel or the earlier 10D. I'm sure that sports shooters and some fashion photographers will still lust for the speed and buffer depth of the Mark II, but for the vast majority of photographers, the performance of the 20D will more than suffice. Big kudos to Canon, on the performance score!
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