<a href=showthread.php?s=&postid=9761672#post9761672 target=_blank>Originally posted</a> by mbunakeith
stopping down means to close the aperture. large apertures are f2.8, f3.5, f5.6 etc..stopped down you are looking at f11, f13, f16, f22 etc...they are called f-stops. the smaller the aperture, the more depth of field your shots will have. the only drawback is light. you need a lot of light to stop down to f16 in your tank. a normal outdoor shot with iso 100 film will expose near perfect at f16 and shutter speed 125/th of a sec. in the tank that is usually hard to do. i would mess around with shutter speeds around 1/30, 1/60, 1/125 and shoot for f8 or f11. a tripod will greatly aid the work.