All SFP scopes have calibrated hold overs. Usually marked with a triangle. Higher end scopes usually have two spots. One somewhere in the high middle range and one at full mag. Sight in using these calibrated areas and your hold overs will be correct. Once you move from these areas your hold overs will be different, but you just need to know that difference on a scope dope. Hold overs can be used at any magnification if you know the changes in POI for the particular magnification. What I do with my powder burners with SFP scopes is sight in at full mag at 200y. Then I will see where the POI is for lowest mag and have that change set in the zero offset feature. On airguns if I am using a SFP I just leave it on the magnification I zeroed the scope at. I am usually never below 8 mag anyway this is never is an issue, but you have to have a good parallax to do this.