LEX

Choose the right ND filter every time – without the guesswork! This long exposure calculator does the thinking for you. You choose the type of photo you want – like blurred clouds or smooth water – – and LEX lists the right ND filters for the job.  You can further choose your degree of effect: from bare minimum to upper end.
 
Features 
* Select the look you want for your photo, from a list of options
* Find out which ND filters ensure that look
* Time the exposure