I must admit I was surprised by the results . I knew the optic trigger was obviously triggered at the speed of light but never knew how long it took for the flash to respond to that trigger . I used some 'special camera gear' , the D50 with its electronic shutter , two SB24's and an optic trigger .

I took a walk on the farm to find some 'different' scenery .

Set up the SB24 on this old shed ....

And the flash wouldn't trigger at more than 30cm away - the ambient was messing with the optic trigger so I went indoors and shot out the door so I could still have some ambient to play with .

I opened the aperture and increased shutter speed to darken the background and give me 1/4000th sec .

After playing around a bit because 1/16th power was too much at F2.8 I eventually bounced the flash off a wooden door to weaken it a bit .

Then I headed home because I could see the cows had the same idea .

The sun was coming out and I wanted to make the optic trigger work outdoors and so I put a tube around it - it still wouldn't work properly until I realized the foil was reflecting too much ambient into the tube so I pushed a black tube into it and this got me 4 metres working distance in sunlight .