fractal
DIS Veteran
- Joined
- May 15, 2013
What he is trying to figure out...
You were about 1 stop faster in your aperture. But you were 1.5 stops darker in your shutter speed. So IF your exposure was equal, then your (Fractal) ISO should have been about a half stop higher than BigE. Yet, your ISO is 1.5 stops lower.
So by his math, there is a 2-stop exposure difference in your images. (You don't include the EC -- the EC is what caused the camera to calculate the right triangle settings, it's not in addition to the triangle).
Now to my eye, BigE is overexposed... is it 2 stops of overexposure? Probably not 2 stops.... But between some overexposure, as well as just possible differences in the ambient light at that moment, and differences in how different cameras calculate ISO, as well as the real transmission of the lens (Not all 2.8 lenses actually transmit that level of light... not all 2.8 lenses are truly exactly equal. Some may be more like F3, for example).
I interpreted he was calculating a 3 stop difference in SS. Also - I think 2.8 to 1.8 is closer to 1.5 stops than 1. Add in the other factors you mentioned and that could easily account for that difference. When I rode SSE last Summer I would have bet a lot of money the lights were dimmer than last time I rode in 2013.