328iGuy wrote in post #14177282
What does it take to trigger a shot during daylight where the subject is fully lit, yet the background is extremely dark?
Well, again, there are a lot of variable there. You can do that with a bare speedlight in close to the subject, no problem. Youll probably be around iso100, F11 and 1/200th of a second. Now, if you want to add a modifier to the speedlight, youre going to be at full power for sure and really really close to the subject. If you want to have a properly exposed mid day sunlight scene, youre going to need an ND filter to allow you to open up your aperture from F11. To get to 2.8, youd need to use a 4 stop ND filter. How this works is that for every stop darker the ND filter makes the scene, you compensate by changing the aperture to a larger opening, a full stop. (3 clicks on the aperture adjuster) Therefore, no adjustment of the strobe is needed and the ambient to flash ratio is kept constant - Only the depth of field changes. Obviously, if you want to go a stop darker, you throw on a 5 stop ND filter, 1/200th (same ambient level, just one stop darker due to the ND filter) and turn up the strobe one stop. This is where the more powerful strobe is needed because if you want day to look like night, youre going to need a more powerful strobe. If you have a 2400ws strobe, you could shoot at F11 AND the 5 stop ND filter and the only light in the entire scene would be from the strobe, even though your subject is in midday sun.
Does that all make sense? Sometimes its hard to organize so much info logically.