ND Filter iphone app

[londonagent]

Can anyone recommend the best one to use? I know it's been mentioned before but I couldn't find it on the forum search.
TIA.

[Gad-Westy]

To calculate exposure times?

I use an app called Longtime. Seems good to me.

[londonagent]

Cheers - that's exactly what I need.
Thanks GAD-W