Flash Grid & Modifier Loss Calculator
Start with your own readings. Calculate the change, verify a frame, and save what works.
Grids & modifiers
Measure output loss and estimate beam coverage.
Measure your grid or modifier’s actual exposure change
A fabric grid, reflector, softbox or diffusion layer does not have one universal stop cost. This tool compares controlled before-and-after readings and calculates power compensation for the measured change.
- Keep power, distance, aim, ISO and meter orientation fixed.
- Measure before and after fitting the grid or changing the modifier.
- Check the face and background separately, and save the measured setup.
If the reading changes from f/8 to f/5.6 with everything else fixed, the measured loss is approximately one stop. Doubling power is the complete-pulse starting compensation.
Does a grid automatically make a softbox hard light?
A grid primarily restricts spread. Apparent luminous area, diffusion, distance and subject placement still influence the shadow transition.
Is the displayed beam width a guarantee of usable coverage?
No. It is the width of an ideal geometric cone from the entered angle. Real modifiers have nonuniform edges and different beam shapes.
Learn the decision behind the setting.
By Dwayne of DNA Premium Portraits, Sacramento-area portrait photographer. See formulas, assumptions and equipment sources.
Want help turning this plan into a photograph?
Bring this lighting goal to a private Sacramento workshop. Three hours, your equipment, one focused learning plan.