P50 Controller providing OJT described a TCAS event when Developmental failed to issue VFR traffic to an IFR aircraft; the Reporter indicating he/she was explaining required coordination to the Developmental during the occurrence.

Narrative

I was providing OJT to a Developmental who was working to several aircraft. While he was attempting to accommodate a photo mission pilot's request that would be close to the primary airport (PHX) and coordinate that operation with the neighboring sector and DVT ATCT; a VFR aircraft climbed into the path of Aircraft X that had been given a descent near Carefree Airport 15 NM NW of SDL. There are numerous VFR aircraft that conduct airwork in and transition this very busy area North of the SDL and DVT airports. I am always issuing traffic advisories and restrictions/vectors to avoid these aircraft in my normal operation. In this case; I was explaining the requirements of coordinating with adjacent sectors and facilities to the Developmental Controller for the photo mission as well as for all the other traffic we had at the moment. Traffic was not issued to the pilot of Aircraft X regarding the VFR aircraft that caused the TCAS alert. Recommendation; I would recommend that during OJTI sessions; the OJTI ensure that the RADAR display is set to his/her standards. In this case; the limited and full data blocks were at a different setting than I am used to and the data tag was leading the RADAR target instead of trailing the target as I normally adjust them to do.