Lizzie,
Actually you are wrong. His 'was' relates to the 'amount' of photographers and not to the photographers themselves. Amount is singular and so one uses the singular form of the verb. Had he said: 'there was certainly photographers' then you would be right but since he used the singular noun 'amount' then he was correct to use the singular form of the verb.
Sorry jky12345, not very helpful either but always happy to right a wrong!
Foldie
