There are only two reasons, in my opinion, to have an objective listed on your resume.
The first reason would be:
1) If you are a student with little to no work experience in a particular field, then it would be appropriate to add an objective so that the potential employer can see what type of job you are interested in.
The second reason would be:
2) If you are changing into a new career after already having worked in a different field. In this case it would be helpful to identify what new industry you are pursuing (if it is not already clear from the resume).
I personally think objectives are an outdated tool, and should be replaced with a “Summary of Qualifications” and/or nothing at all. If it is already apparent from your resume what your end goal is in a position, then repeating the information in an objective and/or “Summary of Qualifications” can be redundant.
If you are going to use the “Summary of Qualifications,” you should keep it short and to the point. There is no need to say more then 3-4 sentences maximum. Also, be sure not to repeat information in your “Summary of Qualifications” that is already listed in other areas on your resume, otherwise you are just wasting page space.