If there is no special advantage, no money whatsoever, then I think an argument can be done to say that there is no valuable consideration given that is sufficient to make it a commissioned work under the Copyright Act.
In such a case, I will argue that only a limited license is given to the organisers for whatever purpose which was contemplated at the time of giving. If at the time of giving, publication in ST was not contemplated, then ST has no right to use the photos, nor does the organisers have the right to give it.
If at the time of giving, publication in ST was contemplated, then it would be up to you to dictate the terms ST has to follow - credits or whatever. If ST does not want to comply, then it cannot use the photos.
To complete the picture, even if at the time of giving, nothing was thought about, you as the copyright holder, can always revoke the license given if at any time you are not comfortable. You can always do this so long as you had not granted a non-revocable license to use.
If you're feeling uncomfortable, then write to the organisers via email to clarify the situation, including stating whatever terms you want and also to say that if they are not complied, you are revoking your grant of license to them.
no basically...i had no special advantage whatsoever, no money...it was done for free. Photos were given to middle man who is giving to ST. I had no discussion whatsoever either...the event organiser just told us that our photos will/may be used by ST...me and my friend basically downloaded the photos unto a hard disk, passed it to the event committee and then just went our way...the photos however were seperated into two folders with both our names containing the photos we took seperately...