Operation and controls
Top of camera controls
The top right of the camera features two control dials, and sees the ISO and metering buttons moved onto the top plate. This means only the AF-point selector is left on the shoulder, making it impossible to press the wrong button with the camera to your eye. It also means there's no room for the top-place LCD featured on previous Sigma DSLRs. The top right of the camera is also home to the exposure mode dial, which gains three user-definable custom settings, making it look less sparse than those on previous Sigmas.
The SD1 offers separate AEL and AF buttons (both with user-definable behavior). Oddly for a twin-dial camera, it's not possible to change Exposure Compensation without holding down the button beside the shutter release - both control dials always do the same thing in P, A, and S modes, and their behavior can't be customized. We think it would make more sense to allow exposure compensation to be assigned to whichever dial isn't being used to control the prioritized exposure parameter (as on any other twin-dial SLR).
The top left of the camera is home to the drive mode dial, featuring a series of familiar options, along with the unusually designated 'UP' mirror lockup position. This can be customized so the shutter is released either on a second press of the shutter button, or automatically following a 2 or 10 second delay after the initial press (Canon and Nikon could learn something from this). The 'AB' auto bracketing position, perversely, isn't actually a drive mode at all, but instead is used to configure any auto bracketing increment to be used. Consequently when the dial is in this position, the camera locks up completely and the shutter can't be released.
The Func. button that calls up an interactive settings screen is also here. This gives a comprehensive at-a-glance summary of the camera's current settings, and allows you to cycle through and change them, which is really useful when working with the camera on a tripod.
Rear of camera controls
The back of the camera has been tidied-up in comparison with previous models. The 'QS' button calls up a 'Quick Set' screen that gives access to eight camera settings, that can then be changed using the 4-way controller in a somewhat unintuitive fashion. The (i) button tells you the firmware, time and memory card status when in shooting mode, and summons up an image details page in playback mode. Finally 'X' is a dedicated cancel button that dismisses displayed menus or screens. It's almost completely redundant - it does little you can't achieve by pressing other buttons - but it does provide consistency of operation.
To the lower right of the 4-way controller is a little LED that lights up red when the camera is busy accessing or writing to the card. We mention this only because you'll see it a lot; it spends an inordinate amount of time lit up while you're shooting. Below that is a little speaker for the AF and self-timer beeps, that you'll probably immediately turn off.
Front of camera controls
The front of the camera is home to a depth-of-field preview button, plus a flash exposure compensation button that needs to be held down as you spin a control dial. Just above both (not pictured) is the flash release button.