It depends on more fact specific information. If the predecessor companies are national and have national recognition, the answer would be to change your trademark; regardless, the other photography companies would have superior rights to you in their local regions. Further, if you are in the same local region as Kevin Jackson Photography, even if your name is also Kevin Jackson, you could still not claim exclusive rights to the use of that name. The right to use one's own name as a trademark is not absolute -- it depends on prior current use of it as a trademark by others. As to the word Photography, it is generic and thus would not be entitled to any protection apart from the total mark. My suggestion is that you come up with several names, do your homework and then see a local trademark attorney. You don't want to move forward, establish goodwill with a specific name, then find out you have to change it. Also, in order to actually trademark a word or phrase, it has to actually be used in interstate commerce and not merely a nominal use. Good luck.
Your proposed Trademark may be merely descriptive combined with a surname and not subject to a Federal Registration. The effect of DBA's depends on facts that you'll tell your Intellectual Property attorney.
My comments have been made without discussion. An attorney client relationship has not been established. There may be conflicts which prohibit my providing you with specific legal guidance. Any contact with you beyond these few general words will start with a disclosure of opposing parties so that a conflict check can be made. You should discuss with an attorney.
Frankly, that is a lousy trademark. It's a common surname. You will likely not be able to register that, and even if you do, it will not stop anyone from using their own name unless you get very famous so that you obtain "secondary meaning". Unless you have a marketing budget like OLAN MILLS, I suggest you get something more distinctive and original.
The question of whether a term is primarily merely a surname depends on the primary, not the secondary, significance to the purchasing public. The Trademark Trial and Appeal Board has identified five factors to be considered in making this determination:
(1) whether the surname is rare (see TMEP §1211.01(a)(v));
(2) whether the term is the surname of anyone connected with the applicant;
(3) whether the term has any recognized meaning other than as a surname (see TMEP §§1211.01(a)–1211.01(a)(vii));
(4) whether it has the “look and feel” of a surname (see TMEP §1211.01(a)(vi)); and
(5) whether the stylization of lettering is distinctive enough to create a separate commercial impression (see TMEP §1211.01(b)(ii)).
I am not your lawyer and you are not my client. Free advice here is without recourse and any reliance thereupon is at your sole risk. This is done without compensation as a free public service. I am licensed in IL, MO, TX and I am a Reg. Pat. Atty. so advice in any other jurisdiction is strictly general advice and should be confirmed with an attorney licensed in that jurisdiction.
It sounds like you would probably benefit greatly by consulting with a trademark lawyer just you are completely understanding the extent of TM protection afforded your mark here.
Further, whenever you endeavor into investing in a trademark it is very important that you conduct the proper clearance due diligence upfront and before you submit an application to the USPTO (and by you I mean the professional you hire not you yourself). In the US, this means searching under both federal (USPTO) as well as common law because trademark rights stem from use in this country NOT registration. This means that acquiring a federal registration does not necessarily mean that you are not infringing on another's intellectual property. See the link below for a detailed explanation of the due diligence process and a guide on how to choose a strong trademark.
I suggest that you consult with a lawyer in private and discuss your objectives in more detail. You can start by calling around to several for a free phone consultation, get some insights then pick the best fit to work with.
DISCLAIMER: this is not intended to be specific legal advice and should not be relied upon as such. No attorney-client relationship is formed with the law firm of Natoli-Lapin, LLC on the basis of this posting.