But really, Binbeto raised a very valid and true point.
The flash units that you couple to your SLRs/DSLRs, even the dinky little ones on your prosumer digicams or P&S are very powerful devices. Standing 10 metres away and you can get disoriented (going the way in Binbeto's post). That's why I emphasize beyond 5m. That's the average high-intensity night sight range from stray cats. Their effective range extend another 2-3 metres more. But anything within the 5m from their faces will be very startling and hurtful.
Since I'm the topic, I'll also remind CSers not to anyhow go around feeding "tidbits" and stuff to strays, just to get shots. You never know that the ones you feed may well be on a controlled diet. End up your good intentions may cause them more harm. (Check up previous posts in Kopitiam and elsewhere for more info...)