John...Sigma uses a proprietary SA mount....but don't let that stop you..you can pick-up some amazing lenses at a good price...the pictures from the Foveon sensor rock....I shoot with the SD14's.....great camera...most people like the SD9 over the SD10...the only issue I ever had with both was battery life...but you can pick-up other batteries and a grip cheap...if you need any questions answered let me know...here is a good site...
www.sigmauserforum.com/forum...
and a picture from my old SD10 same sensor as the SD9...(SD10 was sold)
if you have any other questions please feel free to ask....R.D. sorry for answering your thread...!!!