Response to EV values on a light meter

Update:

At any combination of ISO and EV values, the quantity (f^2)*T is constant. In fact, the constant is:

(f^2)*T= [(2^EV)*ISO]/100

Once this combination is determined, either the f stop, f, can be obtained from inserting T (e.g. for 1/200 th sec, T= 200) (f)= square root{[(2^EV)*ISO]/100*T} or T= {[(2^EV)*ISO]/100*f^2}

The above may be of very little interest to anyone - except those who have respond to the question ("what is the relation between EV numbers and f stop and shutter combinations ?)

Now the final question is this: Presumably EV numbers can be desribed in terms of the nifty "candlepower" or the more hip "lumens"? And is the translation linear? That is, if EV = 1 corresponds to x lumens, does EV = 2 correspond to 2*x lumens.

Thanks for comments or corrections.

Bruce

[ Previous | Next ]