I've read this tutorial about graduated ND Filters and I don't know in which situations I used a 2 stop ND filter or a 4 stop filter
Why should I used a 2 stop GND when my exposure is between 1/100 and 1/25 ? I don't understand the arithmetic. if my exposure is between 1/2000 and 1/30 which filter should I use? 4 stop GND?This can be estimated by first pointing your camera at the darker half of the scene, taking an exposure reading, and then pointing your camera at the lighter half and taking a second exposure reading. The difference between these two exposures is the maximum strength that you'll need to use, although you'll likely want something weaker for a more realistic-looking photo.
Thank you vor your help!