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# Thread: i lost my notes lux2ev

1. ## i lost my notes lux2ev

i lost my notes .does anybody have an equation handy how to convrt lux into ev and visa versa?

2. Hi Ralph:

From Ben earlier today....Check-out ehow.com. Converting Lux to EV; 5.5L=1 EV

Elliot

3. Stack Overflow says:

EV Lux
-1 1.25
-0.5 1.75
0 2.50
0.5 3.50
1 5.00
1.5 7.00
2 10.00
2.5 14.00
3 20.00
3.5 28.00
4 40.00
1 EV is 5 Lux. 2 EV is 10 Lux. 3 EV is 20 Lux. Hmmm. It looks logarithmic:

lux = (2 ^ ev) * 2.5;
(2 to the power of EV, times 2.5)

You can also use Wolfram Alpha, which, e.g., confirms the above math by calculating 10 EV to be 2560 lux.

4. Just remember that those values are for ISO 100, otherwise you have to adjust accordingly.

5. is there an equationthat considers film speed?

6. Originally Posted by fdisilvestro
Just remember that those values are for ISO 100, otherwise you have to adjust accordingly.
Or call it LV.

Steve.

7. i call it luve

8. Originally Posted by RalphLambrecht
is there an equationthat considers film speed?
Based on Brian's equation

lux = (2 ^ ev) * 2.5 * 100 / iso

Where iso is the film speed.

9. But if you have an illuminance reading in Lux and want to covert to EV it's a bit more difficult.
Log(Lux / 2.5) / Log(2)=EV for ISO 100

10. Hmmmm....I think I'll stay with EV values.....:}

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