Lighttools™ Soft Eggcrate™ Exposure Calculator How to Use EggCalc About EggCalc

Step 1. Select Size of Diffuser & Soft Egg Crate™
Model:	None Lightbanks Lowel Rifa-lites Butterfly & Overhead
Style:	None
Width:	1 2 3 4 5 6 8 12 20 Feet
Height:	1 2 3 4 5 6 8 12 20 Feet

Step 2. Meter Position
Horizontal:	Feet	+ 0.5'	- 0.5'
Vertical:	Feet	+ 0.5'	- 0.5'
Distance:	Feet	+ 0.5'	- 0.5'
Step 3.	Calculate

Relative Change in Exposure with Eggcrate on Diffuser:		f-stops
Note:
Distance setting from diffuser and center axis will determine exposure change with use of Lighttools™ Soft Egg Crates™; Minimal center axis change in exposure begins at a distance of 3-4 times the diagonal dimensions of the diffuser; Egg Calc is based on an evenly diffused source such as bounced light exiting through full diffusion material.
Click here for Metric Calculation. For assistance, please call Lighttools Canada @1.800.417.7431 (N. America toll free) or 1.780.438.3860 All rights reserved. ©Lighttools™2005.

Using EggCalc is simple:

1. If you are using a diffuser with a Lighttools Soft Egg Crate, choose the appropriate model from the drop-down Model list. Otherwise, choose None.

2. Select the appropriate beam spread from the drop-down Style list.

3. Select the Width and Height of your diffuser from the drop-down lists.

4. Specify your meter position.

The Distance is measured along a line extended from and perpendicular to the center of the diffuser. The Horizontal and Vertical distances are offsets from this line. The meter is always facing in the direction perpendicular to the diffuser. (Imagine placing the meter on a surface that is parallel to the diffuser.)

If you choose to work in meters rather than feet, Click Metric Calculation.

The Relative Illuminance values are shown in f-stops for both the bare diffuser and the diffuser with an egg crate screen. These values are relative to a light meter reading taken a few inches away from the center of the bare diffuser.

EggCalc assumes that you are using a perfect diffuser. If you can easily see the light source through the diffusion material, then the light is being only partially diffused, and EggCalc will produce only approximate results. Even so, these results will be much better than trying to guess with the inverse square law.

Go Back to EggCalc.

About EggCalc