You're adding a lot of confusion here by arbitrarily defining your own zero. It's like saying you're going to start counting everything from the number 4, so if there are of 2 of something on a table, you're telling everyone there are 6. Makes no sense.
0 EV has a real, absolute definition - an exposure of 1 s, f/1.0, ISO 100.
Technically, your "0" EV is actually EV = 5. That means your -7 EV is really -2 EV (and in fact, the 6D is spec'd to AF at -3 EV, but of course, that may not equate to real world numbers).
It would help avoid confusion if you restate your numbers according to the real definition of EV = 0, otherwise many people will read that you're testing at "EV = -7" and think you're spewing complete
Sorry, but the fact that you don't seem to understand some of the basics, like the fundamental definition of the basis for the specification you are testing, makes me question what you're doing. I definitely appreciate individual testing (and especially the fact that you did post your definition, so the error could be spotted), but post/blogs like this contribute to the vast and growing pool of bad and/or unreliable information out there.
neuro, i have question on this part: base to my conversion of everything back to iso 100, it shows that
- 1/60 f2.8 iso 400 (0) will be equivalent to 1/15 f2.8 iso 100 which is EV 7
- 1/60 f2.8 iso 102,400 (-7) will be equalivant to 2 f1.0 iso 100 which is EV -1
is there something wrong with my conversion? however, taking a look into his images, i guess that he was talking about zone system instead of exposure value, but there is no such -7 zone system, and i am scratching my head over here