I have a player that has a 3rd character that we are switching over to 4th edition with. The character is a phys ad with an infusion focus. Under sr3 rules(Sota 2064, pg 68) you take power cost multiply it by 2, and then take that number as the force of the focus to buy a spell focus at 3 x force.

For 4th edition the cost for binding a spell focus is 4 x force. Does it seem ok to allow this into 4th edition or has the system changed enough to disalow this kind of focus. Or should I just charge more for them.

Old cost (Power cost x 2) x3 = karma cost

New cost ( power cost x2) x4 = karma cost

BlacKat

As in SR4 there is no way to buy Adept powers separate from Magic, the Adept Focus and the Infusion Focus would have to be rolled in one.

The force necessary would simply be the points of Magic required to gain those Powers.
So, actually, it would be more fitting to apply the cost multiplicator of a Power Focus: 8x