Fieldtester reviews the Digisight Ultra LRF N450 night vision riflescope made by Pulsar... "Judging range at night can be a real challenge, even if you know your ground well. Tom from distributors Thomas Jacks is a fan of the Pulsar Digisight Ultra LRF N450 night vision riflescope for that very reason - it has a built-in laser rangefinder that will measure ranges up to 1,000m with an accuracy of plus or minus 1 metre.