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Performance

Overall Performance

The SD1 is not a particularly fast camera; by modern standards it feels a bit slow in almost everything that it does. For almost all operations - playback, menu browsing and the like - this is, while noticeable, not really problematic. The camera does take a couple of seconds to power on or re-awaken from Auto Power Off, though, and this can occasionally mean it will miss shots that we'd expect a camera with high-end pretensions to catch. The biggest problem, though is the camera's card write speed, and its control idiosyncrasies while it's writing.

File write times and function lockup

The SD1's single biggest operational flaw is the length of time it takes to write files to the card. The SD1's Raw files are huge (typically 45-60 MB), and even with respectably fast media, the camera will take 15 seconds or more to write a single file. Most unfortunate, though, is the fact that certain button functions become either erratic or completely inaccessible while it's doing so.

Fortunately none of the primary exposure controls (shutter speed, aperture, exposure compensation, or ISO) are affected, so there's limited impact on the immediate shooting process. But the moment you start pressing other buttons, operation becomes quixotic. The processing and writing of a file appears to occur in three phases; there's an initial period of about 3 seconds during which the activity LED is lit continuously, after which the preview image appears (if enabled). The LED stays lit for a further 5 seconds or so, then flashes away happily to itself until the file is written to the card. The response of the buttons depends on where you are in this process; the table below shows which buttons work when.

 
Phase 1
(~3 sec, LED lit continuously)
Phase 2
(~ 5 sec, LED lit continuously)
Phase 3
(~7 sec, LED flashes)
  Exp Comp, ISO, AF, AEL
Y
Y
Y
  AF point, Metering mode
Y
N
Y
  QS
Y
Y
Y
  Func, Play
N
N
N
  Menu, i
Y
Y
N

The 'QS' button functions normally throughout, which is lucky as the 'Func' button doesn't work at all. The Menu and 'i' buttons work for the first 8 seconds or so while the status LED is continuously lit, but then freeze while it's flashing (indicating that the camera is writing to card). The AF point selection and metering mode buttons behave most oddly; they'll respond for a few seconds immediately after exposure, but then have a 'dead' period about 5 seconds, before reactivating precisely at the point 'Menu' and 'i' stop working.

Perhaps the biggest problem, however, is that you have to wait until write is complete before you can enter playback mode to check focus and exposure. Even for a single shot, 15 seconds is bad enough; if you've taken three or four variants in quick succession, the cumulative delay can become hugely frustrating. If you like to confirm your shots are OK before moving on to the next scene or pose, then you'll find yourself waiting for the SD1 for much longer than you'd like. No other modern SLR is anywhere near as slow in this regard, and any comparable SLR will happily let you enter playback while it's processing.

One partial workaround is to set the image review time to 5 or 10 seconds. This allows you to check basic composition and view an approximate luminance histogram at your leisure; you can switch between the 2 views using the 'i' button. There's still a delay before the preview image appears, but it's reduced to a more-tolerable 3 seconds or so per shot. However there's still no way to browse through your shots, or zoom in to check focus. Depending on how you like to work, this could be either completely irrelevant, or a real cause for concern.

Continuous Shooting and Buffering

The SD1 is unusual in that not only can it record Raw files at reduced resolution, its continuous shooting rate increases when doing so. When set to High (4704 x 3136) its specified speed is 5 fps; at Medium (3264 x 2176) and Low (2336 x 1568) this goes up to 6 fps.

Strangely, in our tests we can't achieve Sigma's specified speeds, but instead measure 4.1 and 5.1 fps respectively. Once the buffer is full, the camera will continue to shoot further frames as space frees up, however this is distinctly sporadic. But again the killer is the time taken to clear the buffer to card; in the worst case scenario, shooting Raw at Medium resolution, this takes fully 2 minutes. During this time all of the limitations described above remain - some buttons just don't work, and you can't enter playback to check what you've just shot.

Image Size
Quality
Frame rate
Buffer
Write Complete
  High   RAW + Fine
4.1 fps
7 frames
~ 80 sec
  RAW
4.1 fps
7 frames
~ 80 sec
  Fine
4.1 fps
8 frames
~ 25 sec
  Medium   RAW + Fine
5.1 fps
14 frames
~ 120 sec
  RAW
5.1 fps
14 frames
~ 120 sec
  Fine
5.2 fps
15 frames
~ 30 sec

All timings using Sandisk Extreme Ducati Edition 4GB CF card.

Compared to other high-end APS-C SLRs, these frame rates look somewhat low; Canon's EOS 7D will run at 8 fps, for example. The write times are very, very much slower than we'd expect from a modern SLR; even when shooting JPEG only, you have to wait 30 seconds for the camera to process and write a full burst.

Autofocus speed / accuracy

The SD1 uses an 11-point AF system which covers a decent area of the frame - most importantly, there are AF sensors covering the various possible 'rule of thirds' compositions. All of the sensors are cross type (i.e. they respond to both horizontal and vertical detail), which aids decisiveness and accuracy.

This illustration shows the spread of the SD1's 11 AF points across the frame. The circle in the center represents the spot metering area.

In practice the AF system works pretty well, but it's not infallible. Occasionally the camera will erroneously confirm focus, even when it's visibly missed in the viewfinder. For this reason, we've found it to be worthwhile keeping a close eye on the finder and readjusting focus if it looks wrong - and the SD1's large finder and better-than-average focusing screen are useful here. The also SD1 offers AF microadjust on a per-lens basis, which allows correction of systematic focus errors.

Focus speed is, of course, highly dependent upon the lenses used. Most of Sigma's recent designs use ultrasonic-type HSM focusing, with a mixture of micro- and ring-type motors. As a general rule, lenses that don't absolutely require you to switch to 'M' for manual focus are ring-type, and tend to be faster-focusing. We've used a mix of lenses during the course of this review, including the 17-50mm 1:2.8 EX DC OS HSM, 105mm 1:2.8 EX DG OS HSM Macro and 12-24mm 1:4.5-5.6 II DG HSM; all have performed quite acceptably.

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Comments

Total comments: 3
Birtrum

I purchased an SD1 for my business of photographing textiles in a studio situation and I feel totally deflated. The actual image quality is excellent, but the tethering capabilities are pathetic. I expected to be able to click from my PC to launch a shot, then instantly see what I had taken, before moving on to the next item, which sadly is not the case. Their software application known as Sigma Capture Pro should be reported to the trading standards council, as there is nothing 'Pro' about it as it is just a glorified remote shutter release program. Furthermore in order to have access to your images on a PC, you need to go into the menu function on the camera and disable the 'remote capture program' then select mass storage to view your images. Going through this process with every shot, may be good for you cardiovascular system, but for someone who relies on seamless throughput to make a living, this camera is junk.

1 upvote
Scottelly

I was looking at the photo comparison today, comparing the SD1 against the new Canon 5 D Mk III, the Nikon D800E, and the Pentax 645 D . . . at ISO 800 . . . and I just can not believe my eyes. Take a look at this:

http://sbkart.com/sd1/SD1-screencap.jpg

The SD1 never ceases to amaze me.

2 upvotes
Scott Greiff

Why won't the comparisons load?

0 upvotes
Total comments: 3