Fran,
I have one that I bought from cabela's about 2 years ago and it is rediculously bright, Mine is not the cabela's brand it is a Cyclops that they used to sell. It too is 20m candle powewer and runs off of a 12v sealed rechargable battery, if yours is anything like this one you will have no problem getting 250yds out of it and it will last a lot longer than 10-15 minutes, my wife calls it the BUBBA light... They can shine as far as you can see when fully charged and mine will last about 30 minutes at full charge and full on...

BTW, those things are not real light weight, you might have to have an extra person to spotlight while you run the camera....