DK on the a99

Ref 2/3 EV loss - as others have confirmed, the split is about 30/70. That's 30% of the light lost. To clarify - 50% of the light lost is 1EV, 1stop. 30% lost is about 2/3EV (slightly less, a 33/67 split would be 2/3rds EV).

It is easy to think '30%' lost means 1/3EV lost. But 1EV is not 'all the light'. 1EV step is always a doubling or halving of the light. Some return to simple math is needed here to relate EV (a doubling scale) to percent or ratios.

My figure is not dead accurate and I should perhaps replace it with a calculated exact decimal point of an EV relating to the 30/70 figure. However, that figure is imprecise, I've listened to Sony's presentations directly and I remain unsure whether the SLT mirrors vary from model to model in transmission/reflection ratio.

David