Very precise observation! Indeed, the camera was not parallel to the coin because my intention was to get a reflection
of the light source rather then that of camera. Of course, this effect is not so dramatic as for bright silver but it is noticeable
for bronze also. By the way, the reverse
due to the camera inclination the reverse
is shorter than in reality.
Unfortunately, the lightflow was at the limit of the captor sensitivity and the upper part
of the coin is out of focus.
Sometmes I add a brighter lamp
. Then, of course, there is no problem with focus but there is a loss of attractvity of the image.
I manipulate with Photoshop to adjust contrast and brightness but did not use color saturation function (I never get something
acceptable with this function). In both cases white balance was "measured". The difference in color palette, probably, should be explained not only by the light composition and its intensity but also the environment.
In fact, a static photo cannot transmit all the richness of an object. We should try to make movies...