Originally posted by acoufap I
If you put the DA TC1.4x into the equation with the DA*300 you get 420mm @ 5.6 open aperture. The DFA150-450 doesn't need a TC for the FL and you get f/5.6 up to 450mm. So in this case both lenses are comparable concerning "light eating".
Maybe I misunderstand what you mean, but in my experience, both lens are not comparable concerning 'light eating'.
My understanding of 'light eating' is that light is lost between lens entry and the sensor.
It all looks pretty much the same in regard to f stop, DA*300 f/5.6 at 420mm, and DFA f/5.6 at 450mm, but that's not a measure of the actual light reaching the sensor.
I'm really talking about the t-stop, and my guess is that the DA*300 + 1.4xTC at f/5.6 is probably not too far from 5.6, whereas the DFA at f/5.6 is probably up around 8....ie somewhere around 1 stop advantage to the DA*300.
I haven't done any controlled tests, they are probably best done indoors with controlled lighting, but real world shooting with the DA*300 does seem to allow lower ISO/higher shutter speeds.
Cheers,
Terry