The couple has been out in St. Lucia this week following their wedding on Saturday ... and it appears Burks is stepping into his husband role nicely -- jumping in when his new wifey was in need of some oceanside pics.

Check out video we obtained of the two as they were soaking in honeymoon rays -- Burks grabbed Shelby's phone when she wanted some photos ... and he then proceeded to make sure to get all of the angles for her as she got her poses in.

Shelby seemed pleased with the job Treylon did -- she took one glance at the set of pics ... before she and Treylon jetted off to their next adventure on the island.

Impromptu photo shoots aside ... the duo appears to be loving their post-nuptial life -- chasing waterfalls and getting some toe dips in the Atlantic Ocean as well.

As for the upcoming football season, Burks is clearly keepin' himself in shape while on vacay ... all of his muscles were on display in a pair of tiny board shorts Thursday.