The phrase “long-awaited” is overused, but sometimes repeatedly appropriate. Sigma Japan’s tendency to preview cameras before launch often leaves the consumer feeling more than a bit confused; when DID the camera actually launch? The SD15, a substantially redesigned digital SLR that replaces the 2007 SD14, comes in on a fairly predictable 3-year product cycle that exemplifies Sigma’s careful approach to evolving their Foveon-based cameras.
With a few headline changes, but the same sensor size and pixel-count as the previous model, will the SD15 tempt anyone but the most hardcore enthusiast to hand over £899?
Whilst at first glance the SD15 looks much the same as the SD14, there have been a lot of changes under the hood. The SD14’s dedicated DSP and architecture had the bandwidth to process pixels as fast as the best DSLRs at the time; a fact often masked by the discrepancy in spatial resolution for the output files – yet it soon got an undeserved reputation for being slower than its peers.
14Mp to move is 14Mp, whether you lay them out flat or stack them three-high. With that in mind however, Sigma leveraged their Fujitsu-sourced TRUE-II processor first seen in the DP2 to give the SD15 a bit more in the speed department, while also introducing a few cost reductions on this unique digital camera. When the SD14 launched in considerably more favourable economic conditions, it carried an RRP of £1199, Japanese products are now battling a much stronger Yen across the board.
No other system uses the Foveon X3 sensor – a technology which has been covered here before, but essentially records true colour at every spatial location by providing Red, Green and Blue sensors in each pixel. Conventional cameras only catch one colour per spatial location.
The upshot of this is that the SD15’s sensor has a spatial resolution of 4.5Mp, but captures 4.5Mp of red, 4.5Mp of blue, and 4.5Mp of green, a 10Mp camera with a typical Bayer CFA will capture 2.5Mp red, 2.5Mp blue and 5Mp green – which it then interpolates over a 10Mp spatial image to calculate the true colours.
You have a choice; interpolate your image up from a pure signal, or never start with a pure signal but try to get enough that the details don’t matter.
Personally, I’m quite a fan of detail. I shoot with a D3S, a camera which only has 12Mp but incredible light gathering performance and speed, but prior to that no camera I tried would tempt me away from Sigma and I still miss the texture and quality of the Foveon’s image. The SD15 is a luxury second body, something to play with the art rather than the job of photography. Has Sigma done enough to let that art be practised without technology tripping the system up?
Physically the SD15 is almost identical to the SD14. The details are modified in that there’s now a backlit, with backlight control, upper LCD, and the rear display is much larger and higher resolution. The controls have been shuffled, but the essential shape and handling of the camera remains much as it was; a pleasant, solid but largely hard-plastic exterior small DSLR.
The compact flash card slot has been replaced by SDHC; a side effect of the TRUE-II, and the upper panel controls hint at the new mirror lock-up mode made possible by the two-motor reflex system. Lock up? On a DSLR? Surely there’s a live-view then!
No, there’s no live view on the SD15. Possibly for technical reasons as the live view output (coincidentally the same as the resolution of the recorded video mode) of the DP series would occupy a small area of the LCD, and I’ve a suspicion that the TRUE processor can’t provide any more.
The TRUE CPU is an evolution of a 3CCD video camera solution, where data would be directly fed to a stream, and the only use for live view – as we see it – would be feeding an LCD/EVF. Sensor heating could also affect it, though the DP series with their live-view and lack of a mirror box to aid cooling haven’t shown any signs of that.
There’ll be more here soon; this is a quick preview of my review camera and full reviews will be going to their specified outlets – but I can’t resist showing a few little clues…