Originally Posted by rick
You could just do a millimetre scale around the entire circumference they could then set the zero at what ever point they want and do a simple chart, something like 4.4mm = 50yds or meters, 5.6mm =55yds/mm depending on your choice of measurements. Adjustments for temperature, colour of target, variations in the users eyes and any other variation in the scope could be easily compensated for. You wouldn't need separate index marks for normal and cold temperatures.
Once you know the reading for each distance compensating for variations becomes simple and the more anal ones out there could easily work out distances to the yard.
Sounds complicated to me
It'll all hinge really on how clear the marks print out - if I have to put a mark every 1mm then it's going to be a raised mark that's 300 microns wide - that might be a bit too fine for you to be able to make out on the printed thing.