Exercise: Improvement or interpretation?

For this exercise I had to look at creating the old darkroom techniques of dodging and burning digitally.  Although there are a few ways in which you can do this, I chose to use the Adjustment Brush in Lightroom as I felt it gave me personally more accurate selections and control over the image.  I think the results were more realistic looking too compared to what I would achieve in Photoshop.  This probably has more of a bearing on my Photoshop skills than the software itself.

The before image.  

And after dodging and burning

I felt that the bookshelf in the background was rather distracting and took away from the subject in this picture.  I adjusted the exposure to darken the image and then used the Adjustment brush to make local exposure adjustments to the subject.  In addition I added a blur effect to the background to give a lens blur effect.   

The enhancements of this image are realistic in the sense that it is just the lighting effect that has been altered. This draws the viewer's attention to the subject as he stands out more from the background.

I feel that there are limits with this type of enhancement which would be reached once the lighting effect looked odd and not in any way realistic.  The additional blur effect affects the depth of field naturally.  Had I used a wider aperture when I shot the image I would have achieved that result.

Perhaps the limit is reached when you know that the alterations/enhancements you have made could not be achieved in camera at the time of shooting.