Shutter Lag/Cycle Times
When you press the shutter release on a camera, there's usually a delay or lag
time before the shutter actually fires. This time allows 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 almost never reported on, and can significantly
affect the picture taking experience, I now routinely measure it.
NOTE: My qualitative characterizations of camera performance below (that is, "reasonably
fast," "about average," etc.) are meant to be relative to
other cameras of similar price and general capabilities. Thus, the same
shutter lag that's "very fast" for a low-end consumer camera might
be characterized as "quite slow" if I encountered it on a professional
model. The comments are also intended as only a quick reference: If performance
specs are critical for you, rely on the absolute numbers to compare cameras,
rather than my purely qualitative comments.
EOS 300D Timings
Operation
Time (secs)
Notes
Power On -> First shot
3.09
Average to a bit slower than
average for an SLR. (No lens to deploy.)
Shutdown
5.21
Time to write large/fine image
to the card. (Time will vary greatly with card speed, this is for a pretty
fast CF card.)
Play to Record, first shot
0.64
Time from playback mode to
ready to shoot.
Record to play (max res)
5.34/1.22
Time to display large/fine
file immediately after shot is captured.
Shutter lag, full autofocus
0.250/0.278
AF speed will vary greatly
depending on lens used. These numbers are for EF-S 18-55mm. Quite fast.
(Typical for an SLR, way faster than even high-end point &
shoot models.)
Shutter lag, manual focus
0.248
Time with same lens as above,
but set to manual focus mode. Average to a bit slower than average for
an SLR.
Shutter lag, prefocus
0.142
Delay with shutter button
half-pressed and held before the exposure. (This number won't vary between
lenses.) Fast compared to point & shoots, but slower than average
for SLRs.
Cycle Time, large/fine JPEG
0.46/2.30/4.53
First time is interval between
first four shots, second time is for subsequent ~4 shots, then drops to
third time for all following. Quite fast for first four shots, not bad
for the following 4.
Cycle Time, small/basic JPEG
0.46/2.35
First time is interval between
first four shots, second time is for all subsequent ones.
Cycle Time, RAW mode
0.65/2.27/7.27
As above, first time is interval
between first four shots, second time is for subsequent ~4 shots, third
time is for all subsequent. Interestingly, RAW-mode cycle time is slightly
longer than that for JPEG files, even when writing to the buffer memories.
Still plenty fast though.
Continuous Mode, large/fine
JPEG
0.40/1.81/4.25
As above, first time is interval
between first four shots, second is for second 4-5, third time is for
all subsequent. Pretty fast. Buffer clears in about 17 seconds with a
fast memory card.
Continuous Mode, small/basic
JPEG
0.40/1.73
As above, first time is interval
between first four shots, second time is for all subsequent ones.
Continuous Mode, RAW mode
0.40/2.18/7.63
As above, times are for first
four shots, the following 4-5 shots, then all subsequent. Quite fast.
Buffer clears in about 21 seconds with a fast memory card.
Overall, the EOS Digital Rebel 300D is a surprisingly nimble camera. Full-autofocus
shutter lag is on a par with other low-end SLRs on the market, and shot
to shot speed is very good. What surprised me the most about the camera was
how responsive it felt in normal usage, even when I was shooting the wide
range of bracketed exposures I use for some of my test shots. Despite the
buffer being only 4 frames deep, I almost never found myself waiting for data
to write to the card. I suspect that this is because of the 300D's dual-buffer
design (see the note below), that lets the cycle time degrade a bit more gracefully
once the primary buffer is filled, and that lets it clear the primary buffer
memory very quickly, the moment you stop shooting. Whatever the case, the
300D certainly doesn't shoot like a cheap camera, at least in the speed department!
Two Buffer Memories?
As with the D60 and 10D before it, the Digital Rebel 300D seems to have two
buffer memories. It will shoot very rapidly for the first four shots at
any JPEG resolution setting, then slows somewhat for the following four or
five, and finally drops to a much slower speed for all subsequent ones. (At
the small/normal size/quality setting, I never hit the slowest time though,
there were only two steps in its cycle time performance.) It seems that it
has a primary buffer that can hold four shots regardless of image size (perhaps
buffering the sensor data directly?), then a secondary one good for four or
five shots at maximum resolution, after which it finally has to slow down
all the way to wait on the memory card for each shot.
I'm not sure how to interpret these results (although I suspect I'm right
that the camera initially buffers data directly from the sensor), but the
bottom line is a bit more graceful degradation of cycle time as you eat into
its buffer capacity. The net result is very efficient processing and a surprisingly
responsive "feel" to the camera.
