I am shopping for some indoors, where i do not want to leave lights on. Really only posted because I was surprised to see a 42xx with only a 20% markup and a warranty stateside, these do look drop shipped though.
You are certainly right on the max App. The progression is logarithmic, so that 1.4 is a 2x-3x bigger lens opening, ie more of an ever bigger circle exposed. That being said, usually variable focal lengths leads to a changing max App. The specs on the 5231 does not list a max App split so it is possible/common for the max App to maintain across small focal length ranges, but it the SD65c131U-HNI does list a split. I mention that because that means you should have to adjust shutter speed at max zoom on the 30x cameras to maintain the light saturation, and I wonder if the auto-focus accounts for that. Keeping in mind that with apertures this large that you would still be making adjustments on the fast side of the list.
