Older models have fixed (hard coded) focal lengths 21mm, 24mm, 28mm, 35mm and only 2 slots with option to modify the focal length.
Newer models (e.g. X-T3) have option to set your own custom focal length to all slots, so you can use e.g. 12mm, 30mm, 42mm, 58mm, 85mm, 105mm and just select another preset instead of manually setting the focal length you are about to use.
Please make all focal lengths customizable even on the older cameras.
Older models have fixed (hard coded) focal lengths 21mm, 24mm, 28mm, 35mm and only 2 slots with option to modify the focal length.
Newer models (e.g. X-T3) have option to set your own custom focal length to all slots, so you can use e.g. 12mm, 30mm, 42mm, 58mm, 85mm, 105mm and just select another preset instead of manually setting the focal length you are about to use.
Please make all focal lengths customizable even on the older cameras.
This is also related to #1