Unless the image was taken on a large format digital camera or, say, a 10 inch plate camera then I wouldn't recommend using a photo at all. Yes, companies
do use photos but it's usually only the preserve of the nationals/multinationals who can afford the outlay for high resolution imagery.
If your client will only ever use it on a website then fair enough. But how will the logo cope when, one day, it's on the side of a van? Or even a billboard?
Take a look here:
Logo Design and How to Avoid Disaster!
:)