awtan: It's a shame that OS is unavailable for A-mount.Can not switch from old 17-50/2.8 OS for Sony NEX w/la-ea2 via that.Hate that marketing things..
The Sigma part number for the Alpha mount OS version is 668624
The OS version *does* exist in an Alpha mount. I have one. But they removed the OS after a short production run. I managed to find one and I'm quite happy with it on my Sony A580. It might be possible to find one still but you'd have to be very careful since the vendor might not notice the distinction. I am not at home right now but if you want the part number, I can look it up when I get home.
Blorf: I have a Sony HVL-F56AM flash that I use with my Sony A100. It triggers with the built-in flash. How does this camera trigger it without a built-in flash?
It doesn't. You will need to use a cable (which means that you will lose ADI metering and high-speed sync) or you will need to purchase another flash such as the hvl-f43am. You can probably use a third-party flash such as a mecablitz which could be a fair bit less expensive.
This is a very captivating picture. I love how well the brick echoes the skintones. I'd like to know more about how this picture was made, if you don't mind. In particular, it looks like it was taken at night where one expects horrific sodium vapor or mercury vapor lighting. And yet the colours look amazing. Can you please share with us how you lit this scene?
Also, what's with the hands and the tree? They look almost CGI. Is that an artifact of exaggerated sharpening?