- otherwise there wasn't enough light / the light was too concentrated into a tight spot.
If a light has too tight a spot (which most do as they are torches), then some translucent gel sheet as used in theater lighting can even it out. I was given some, but you should be able to source it somewhere.
Cut a disc - or two - to fit over the torch lens, and it will give a more even lighting.
I'll try to upload a video taken using one, though with a fairly rubbish cam.