If not, try typing 'Today' in the'When' box and see that the current date is calculated. To search on only one of the fields make the entries in the 'What' box. Type the photographer's name in the 'What' box. In other words, if you searched on John Smith you'll pick up all the John's and all the Smiths. This searches for the exact name entered, hence the aformentioned problem.
Case is unimportant.
You can type any part of it and get more or fewer images. You do not need to specify the field.