Hello
1.5 Vf is enough
It's not only enough, it's the operating value.
TRYING TO OPERATE THE SFH485P AT 3V IS AN ERROR. YOU WILL FRY THEM
Also 100ma is a max value.
Please use 75 mA max to power them.
If you use 100mA with freetrack your leds will be overpowered.
About the resistor value, please use the led wizard on the web frontpage, and provide the power supply you plan to use and your leds characteristics (1.5v and 25 to 75 mA, depending of your webcam setup) and it will provide the resistor values.
cya