What do these adapters do to the depth of field? If you add a fisheye adapter to a 16mm lens is the equivalent depth of field that of a 16mm fisheye lens?
1) the depth of field does not change if you add a fisheye lens and RETAIN THE ASPECT RATIO. It only gets bigger or smaller if you change the f-stop.
2) The depth of field will be bigger if you use a fisheye converter and RETAIN YOUR SUBJECT DISTANCE (but then all subjects will become smaller. If you want to have the same size as before, you must get closer, and then see 1).
Underwater the old rule "Best wide angle lens? - Three steps back!" cannot be applied: You normally will use a wide lens not to get "more landscape", but to get closer and thus have less water between lens and subject.
A 100mm lens and a 12mm lens have the same depth of field if you use the same f-stop and the same aspect ratio, but with the 12mm lens you are much closer.
Hope this helps.
Yes of course you are right. I was exaggerating a bit :-) If you ask people, most 8,12,16 or 24MB pics are viewed at their computer screen in a fraction of the 100% view - so a tiny compact camera would indeed be "good enough". My point behind this is that I doubt that the hunt for "THE" lens makes sense for the average amateur user. On the other hand, it is a hobby, and there is nothing like rational thinking involved...
Edited by Jock, 01 September 2011 - 01:26 AM.