David Mark Walking Under Giant Fern How come here in the outside you use 250 asa, and inside the caves 100 ? Diana Thursday, February 7th, 2013 at 02:03:06 Outside was hand held - 1/30th of a second at f2.8 is as slow as I am willing to go (and the lens opens up). In the cave I used a tripod so the difference between 0.5 seconds or 1 second is pretty much nil. John Harvey Wednesday, February 20th, 2013 at 23:04:31