Sigma SD1 Hands-on Preview

Preview based on a pre-production SD1 with firmware 0.94

The SD1 created a great deal of interest at Photokina 2010. Having used Foveon's original 4.7x3MP sensor in its SD and DP series of cameras, Sigma bought the sensor company in 2008 and instructed it to focus its efforts on high quality stills photography - specifically the 15x3MP sensor that the SD1 is built around. Now, not long after the originally-proposed launch date, the SD1 is here.

The first thing to be addressed has to be the price, and let's not dance around this: the SD1 is eye-wateringly expensive. Even with Sigma listing lens kits for pre-order at significantly below its own suggested price for the body alone, it's still a hugely expensive piece of kit. The company is talking in terms of the SD1 being a portable alternative to medium format cameras (which may not be entirely unfair, as the sensor has the potential to produce resolution similar to a 30MP Bayer-type sensor).

Ultimately, the entire research and development cost of the sensor has to be recouped from the number of cameras the company expects to sell and, sadly, the MSRP suggests that Sigma only expects to sell medium format quantities.

You could, of course, argue that it might sell twice as many if it sold them for half the cost, but that isn't the tactic Sigma has chosen. To look at it another way, the company has decided it has a better chance of charging a premium over Nikon D3X money and selling a handful of cameras, rather than charging the D300 price-tag many existing users were hoping for and have to sell mass-market volumes. It doesn't make sense to dwell much further on this decision, no matter how self-fulfilling it seems. Instead we'll take a look at the camera, what it offers and how it behaves.

Obviously the SD1's defining feature is the new 15x3MP Foveon sensor. For those of you who haven't come across the technology before, it uses a fundamentally different method for detecting color than any other camera sensor. Almost all other cameras place a pattern of colored filters in front of their sensors so that each individual photo site is only receives either red, green or blue light. To create a full-color pixel in the final image, clever mathematics is applied to estimate the values of the two unmeasured colors, based on the amount of those colors captured by adjacent photos sites.

Foveon's technology doesn't use filters - instead it uses the fact that different colors of light can penetrate silicon to differing extents. Foveon's chip measures the number of photons captured at three different depths in the photosite - depths corresponding to how well Red, Green and Blue can penetrate the chip. The main advantage of this is that, unlike other digital cameras, the Sigma measures all three colors at every one of its 15 million photo sites, capturing three times as much color data per-pixel as a conventional sensor. (Hence the company's reference to it being a 46MP camera).

Because the Foveon sensor captures full color data at each pixel location, it's not susceptible to color moiré - false color patterns that are the result of those clever calculations occasionally getting things wrong, for example with finely-woven fabrics. Traditional Bayer-pattern sensors suppress this by using an optical low pass (or anti-aliasing) filter that slightly blurs the image at the pixel level, reducing the camera's resolution. The Foveon sensor doesn't use an AA filter, and is therefore able to resolve substantially more detail than its pixel count alone might suggest.

Beyond that, the SD1 is a camera with a solid specification, though not one that would stand out in the enthusiast-grade DSLR sector, much less so when pitched at the price of the likes of Canon's EOS-1Ds series and Nikon's D3X. The other potential hurdle for the SD1 is its use of Sigma's own SA lens mount. The company builds a wide range of lenses for the mount, but a question mark has to hang over how many of them will live up to the standard demanded by a $9,000+ camera, and how many people will be willing to risk spending money building up a collection of lenses for a non-mainstream mount. It's also worth noting that very few of Sigma's lenses offer any form of weather sealing.

Sigma SD1 specification highlights

• 15x3MP Foveon X3 CMOS sensor
• ISO 100-6400
• 11-point AF sensor (all cross-type)
• 5 frames per second continuous shooting
• 460,000 dot LCD screen
• Shutter capable of 1/8000th second and rated for 100,000 cycles
• Per-lens AF fine tuning

  Body & Design

  
  The SD1 features a new body, significantly evolved from the design of the SD14 and 15. The result is a very conventional camera (in the best possible sense) with twin control dials and direct access buttons for all the key photographic settings, making it quick and easy to operate with the camera to your eye.
  The buttons that were clustered on the top-right-hand corner on previous Sigma models are spread out more sensibly across the top of the SD1. And, although they're not necessarily perfectly placed from a comfort perspective, they're well separated so you can find the right one by touch alone. The side-effect of this rearrangement of buttons is the loss of that endangered species - the top-plate LCD.

  In your hand

  The SD1 is a remarkably well weighted camera - its resin construction feels solid but not overly-heavy. If we are to buy into Sigma's idea of this as an alternative to medium format, then this is a great strength. It fits comfortably in the hand, and it's easy to imagine it remaining comfortable after many hours of use.

  As mentioned, the SD1 is a very conventional-feeling camera. No concessions have had to be made for movie shooting or live view - the camera does neither. There are no special processing options or gimmicks - no dynamic range expansion, no HDR, 3D mode or creative effects. Instead it just gets on with being a traditional SLR - direct access is offered to all the basic shooting parameters, with two dials that focus almost solely on controlling aperture and shutter speed.
  For almost all of its use the SD1 is a simple photographic tool - perhaps elegantly so, from some shooters' perspectives. The only disappointment is that in either Shutter-Speed or Aperture Priority mode, both control dials are devoted to the prioritized parameter, meaning you have to press the exposure compensation button to move away from the metered exposure value. It would seem more logical to devote one dial to exposure compensation or at least make it a configuration option.
  

  	With no HD output to worry about, the SD1's connectors are fairly minimalist - there's a DC power input, remote control socket, USB/AV connector and a flash sync port.
  	The SD1 uses the familiar BP-21 battery. It's a 12Wh battery, though we don't yet know the CIPA battery life rating. The battery itself sits behind a latch-operated door with environmental seals around the edges. The door can be removed for the addition of a battery grip.
  	As with previous Sigma DSLRs, the SD1 features a protective anti-dust screen at the front of the lens mount.

  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 place. 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. This gains three user-definable custom settings, making it look less sparse than previous Sigmas. The SD1 also offers separate AEL and AF buttons (the latter with user-definable behavior). Oddly for a twin-dial camera, it's not possible to change Exposure Compensation without using the button beside the shutter release - both control dials always do the same thing in S or A mode, and their behavior can't be customized. We're unsure why exposure comp. can't simply be assigned to whichever dial isn't being used to control the prioritized exposure parameter. The top left of the camera is home to the drive mode dial, featuring a series of familiar options, along with the unusually designated, customizable 'UP' mirror lockup and AB auto-bracketing positions. The Func. menu that gives access to an interactive settings menu is also here. Rear of camera controls The back of the camera has been tidied-up in comparison with previous models. No buttons on the SD1 are expected to perform multiple duties. As such, rather than re-pressing the menu button to cancel a menu decision, there's a dedicated cancel (X) button. The (i) button tells you the firmware, time and memory card status when in shooting mode, and summons up a details page from playback mode. Front of camera controls The front of the camera is home to a depth-of-field preview button and a flash exposure compensation button that needs to be held as you spin a control dial. Just above both (not pictured) is the flash release button.