Your camera is fine. Lighting a lot of the time is the issue. @Lehigh96 summed your last coin up, to a T. Do you have any others to share? Some may be worth conserving, but there is a proper way and a wrong way, I have never gone beyond a simple acetone or xylene dip/rinse as I do not trust myself to do the job correctly. There are many here that know how to get the correct results, if you are confident in following there advice. Yet it has to be the right coin for conservation.