[Geoff45 (Geoff)]

Originally Posted by EzyStyles

well it didn't work for me doesn't mean it won't work for you just think twice the F-fatio means twice the exposure time

Actually it's worse than that: twice the focal ratio means four times the exposure. A 1mm by 1mm (area 1 sq mm) square goes to a 2mm by 2mm square (area 4 sq mm), so your light is spread over 4 times the area and hence 4 times the exposure.
Geoff

Woops! should have read the whole thread before replying.