Trying to Choose New Camera and Lenses: Olympus OM-D vs Sony NEX

texinwien wrote:

Thanks, but I already knew the answer

The question is, why would Mr. Noble tell the original poster not to double the F number and simply leave it at that, when the original poster is obviously interested in and uncertain about the answer, and when Mr. Noble's answer is incomplete and, at best, misleading.

The correct answer, as you've stated, is to double the F number when DOF is key, and to leave it untouched when light-gathering is key. Furthermore, in my understanding, 'equivalence,' in this context, refers to DOF. The original poster specifically mentioned 'equivalence,' meaning that his doubling of focal lengths and F numbers was correct, in opposition to Mr. Nobel's claims otherwise.

As you can probably see, Mr. Noble likes to play cat and mouse games. He's yet to answer the question, although I'm quite sure the question has been clear to him since yesterday.

Anyway, thanks for the confirmation. Hopefully the discussion will be of more use to the original poster, and to others learning about equivalence, than Mr. Noble's misleading and unhelpful answer was.

tex