“if our photographer was” or “is” or “were”?

If I am not mistaken, the correct conjugation of the verb is 'were'.

This is a case of the subjunctive mood, now rarely used in Modern English. To clarify, the subjunctive mood indicates a state of being or reality or may be used to express a wish or possibility.

In your example, the complex sentence (which is also a clause) "It would be appreciated if our..." contains the modal verb 'would' and the subordinating conjunction 'if'. Usually, in order to be most formal as is implied in your entire example, the verb '[to] be' must be conjugated in the past tense third person plural as a consequence of the modal verb and the subordinating conjunction 'if' which indicate the need for this specific verb tense and, thus, demonstrate the subjunctive mood.

Hope this is clear enough :)

Generally speaking, there is no difference between the subjunctive and indicative form of the verb except for the present tense third person singular and for the verb 'to be', as is the case in your example.