This has not much to do with filter. It's purely an issue with subnetting and VLSM/CIDR
Do you want to match the addresses from 10.50.0.0 to 10.255.255.255?
This consists of:
10.128.0.0/9 (10.128.0.0 - 10.255.255.255)
10.64.0.0/10 (10.64.0.0 - 10.127.255.255)
10.56.0.0/13 (10.56.0.0. - 10.63.255.255)
10.52.0.0/14 (10.52.0.0 - 10.55.255.255)
10.50.0.0/15 (10.50.0.0 - 10.51.255.255)
You can find some helpful subnet calculator tools: http://www.subnet-calculator.com/subnet.php?net_class=A
But didn't find a perfect tool for this case.
BTW, this is really a BAD requirement. Anyone who operates the network should convert their minds to be more "binary"