Deltas is used to measure options!
http://www.investopedia.com/articles/optioninvestor/03/021403.asp
Every single stock has 100 deltas, isn't it true!?
Where can we find a stock (or futures) of 50 deltas to buy? Personally I can't!
No a stock has a delta of 1... Delta is how much the value of something changes when the underlying changes by 1... so for stocks, it's 1...
For an option it depends on which strike compared to underlying, and also depends on volatility, interest rate, dividend... etc.
So if it's ATM, it is indeed (close to) 0.50... but the usual multiplier is 100, so an ATM call has 0.50 x 100 deltas. You buy 1 call, the stock moves up $1... the call value goes up by 0.50, but position value up by $50...
So 1 ATM call option = 0.50 x 100 = moves like 50 stocks... untill gamma kicks in. If you need to get your theory updated from investopedia and wikipedia... I'd be worried....