The Sigma SD15 is a digital SLR introduced in 2010, built around Sigma's Foveon X3 direct image sensor and the SA bayonet mount. It was positioned as an enthusiast body for photographers wanting the colour rendering of the Foveon sensor rather than a conventional Bayer-pattern CMOS.

With only a single UK auction record on file — a 2022 hammer of £50 — there is not enough data to quote a meaningful price range or median for what an SD15 is worth in 2026. That figure was a saleroom hammer result and excludes commission, so the true cost to the buyer would have been higher; today a clean, working example with the SA-mount accessories typically sells for more than a body-only lot in unknown condition.