How can I compare low light performance for different formats? Are there some standard equations to do this?
For example, let's say I want to compare these three camera-lens combinations:
- Nikon NIKKOR Z 58mm f/0.95 S Noct Lens on a Nikon D850
- Fujifilm GFX 50R Medium Format Mirrorless Camera with the bundled 45mm lens
- Olympus OM-D EM1 III with a Voigtlaender Nokton 0.95 42.5 mm lens
When the formats are the same, then F-stop gives a low light comparison, but if the formats are different, then it gets a lot more complicated obviously.
Note that when I speak of "formats" I am including sensor characteristics. So, the variables are: sensor sensivity, sensor size, and lens brightness.