I can’t figure out what (light) stop would be. Here is what I assume- true or false: Light stop is equivalent to 1 EV If you double light stops value you double the light intensity entering the sensor In order to double the amount of light you need to exponentially increase number of light source. Eg. 2 light bulbs will yield 1 light stop, 4 light bulbs will yield 2 light stops more intensive image, 8 bulbs- 3 stops and so on. Each time you increase amount of light by one stop you (need to) double previous amount of light source? 1 light source is 1 light stop? 2 light sources is still 1 light stop? 1 light source is 0 EV, 4 light sources is +1EV? I understand aperture affects exposure. So e.g. Panasonic 20mm f1,7 will have XY value of light stops on m43 or 43 body and the same amount on full frame body, but the difference will be visible in DOF which is, let say, side effect of sensor size. Fast lens is fast lens no matter which body it is mounted on, right? ISO value has also an effect on the exposure. Doubling the ISO amount, we double the sensor sensitivity- ISO 400 is 4x more sensitive/ will produce 4 times more light intensive image than ISO 100? ISO 800 is 8x more, ISO 1600; 16x...? What is the ratio between aperture and light stops? I understand there is chart which explains this: 1.0 1.4 2 2.8 4 5.6 8 11 16 22 -> Each of this aperture is by 1 light stop more intensive to light than the one before? Or If I need faster shutter speed I would be able to use 3 times faster shutter speed (if aperture changes from f4 to f2 or from f16 to f8). Thanks for help!