You can invite photographers to be "contributors" to your listing, giving them the ability to upload photos to a listing. Photographers will not have the ability to view or edit listing data or to publish listings; they can only interact with the Listing Media interface.
Next to the Continue to Listing Media button, you'll see one or more profile photos along with a "+" button. The profile photos indicate users who have been added to this listing as "contributors".
Hovering over a profile photo provides more detail about that user. Clicking the "+" button opens a dialog that allows you to invite another user to be a contributor on the listing. If the person is already a Listing Input user, they'll be added automatically and informed of the invitation. If the user is not (normally, this would be a new photographer), the user will receive an email invitation to start using Listing Input along with instructions on how to do so.