To start off this post the right way I would like to say that this photo was unplanned and was a little or trial and error! so bare with me as I will have to work backwards in my thinking. To begin I will start by showing my set up.
As you can see my camera of choice was my Sony Nex 7. If you look on camera right you will notice that I have my trusty minolta auto 128! The awesome thing about this flash is that it has two settings, auto and manual =) I had mine set to auto. From what I know of the flash it uses a little light meter on the front to read the light that is reflected off the subject; other then that, I can not be much of help. I am clueless when it comes to explaining the algorithm that it uses to know how much light is needed.
The photo as said was a bit of trail and error. Being that it was midnight when I came up with this idea I was being a bit of lazy and chimped my way to what I thought would be workable in photoshop. My goal was to kill all the ambient, saying that I had my aperture set to 5.6 and my flash on auto.
This was my out of camera JPG (I forgot to set it to raw). From here I imported it into photoshop for some well needed editing.
Here the first thing I did was to use the PEN tool to make a selection.
TIP: Zoom in when making your section points.
After making my points all around the camera I then made a selection of the area and then feathered that selection with a radius of 5px
Next I copied that selection and pasted it.
Once pasted I deleted the original background photo.
After deleting my original photo I then added another black layer and used the paint bucket to fill in that layer with black. From there it was a simple change of layering from normal to lighten and cleaned up the photo to delete the parts that didn't look natural.
Once finished with cleaning up the photo I then adjusted my Black point and added a bit of grain giving me my finial image!