Canon Speedlite 90EX Instruction Manual page 34

Flash Shooting Range Guidelines
ISO speed
100
200
400
800
1600
3200
6400
12800
32
EF-M18-55mm f/3.5-5.6 IS STM
18mm (f/3.5)
1 - 2.6 / 3.3 - 8.5
1 - 3.6 / 3.3 - 11.8
1 - 5.1 / 3.3 - 16.7
1 - 7.3 / 3.3 - 23.9
1 - 10.3 / 3.3 - 33.8
1.3 - 14.5 / 4.3 - 47.6
1.8 - 20.6 / 5.9 - 67.6 1.1 - 12.9 / 3.6 - 42.3
2.6 - 29.1 / 8.5 - 95.4 1.6 - 18.2 / 5.2 - 59.7
55mm (f/5.6)
1 - 1.6 / 3.3 - 5.2
1 - 2.3 / 3.3 - 7.5
1 - 3.2 / 3.3 - 10.5
1 - 4.5 / 3.3 - 14.8
1 - 6.4 / 3.3 - 21.0
1 - 9.1 / 3.3 - 29.8
[Approx. m / ft.]
EF-M22mm f/2 STM
22mm (f/2.0)
1 - 4.5 / 3.3 - 14.8
1 - 6.4 / 3.3 - 21.0
1 - 9.0 / 3.3 - 29.5
1.1 - 12.7 / 3.6 - 41.7
1.6 - 18.0 / 5.2 - 59.0
2.3 - 25.5 / 7.5 - 83.6
3.2 - 36.0 / 10.5 - 118
4.5 - 50.9 / 14.8 - 167