What is 90mm f3 5 on micro four thirds in full frame?

90mm on Micro Four Thirds gives the view of 180mm on full frame. For the same depth of field, f/3.5 there behaves like about f/7 on full frame. Exposure doesn't change: f/3.5 gives the same brightness on any sensor.

The same view on every common format:

• Medium format (44 x 33): 228mm at about f/8.9 for the same depth of field
• Full frame: 180mm at about f/7 for the same depth of field
• APS-C: 120mm at about f/4.7 for the same depth of field
• APS-C (Canon): 112mm at about f/4.4 for the same depth of field
• Micro Four Thirds (yours): 90mm at about f/3.5 for the same depth of field
• 1-inch: 67mm at about f/2.6 for the same depth of field
• 1/1.3-inch: 50mm at about f/1.9 for the same depth of field
• 1/1.7-inch: 39mm at about f/1.5 for the same depth of field
• 1/2.3-inch: 32mm at about f/1.2 for the same depth of field

Crop factors are by the sensor diagonal, rounded as they're usually quoted; a format with a different shape (4:3 against 3:2) frames a little differently across the width. More in the focal length converter.

Computed from the sensor sizes, not written by a model.