Nice to see a thread on Dark Frame Insertion (DFI) as it's just not discussed enough, IMHO.
I can't use DFI on my HW50ES with 24p content b/c of the pervasive flicker. It appears to me to be 48Hz flicker, though I'm just guessing, based on my observation that the frequency of the flicker appears to be similar to the flicker present when viewing 3D on the HW50 (which is supposed to be 48Hz). For all I know, it could be 24Hz flicker. I have no way of measuring. It's very evident in bright scenes; less so in darker scenes.
Interestingly, I haven't seen any complaints about flicker with DFI on the VW1000ES. I don't know, however, if that's because it's really not there, or because there's not a large enough sample pool (not many people own the VW1000ES) to get an accurate assessment!
FWIW, here's a schematic I drew up of the different schemes of DFI one could have, & what frequency the panels would have to operate at to achieve any given frequency of dark frames:
Basically, I believe the HW50ES panels can't operate any faster than 120Hz. Hence, the 50ES is likely limited to 96Hz processing when DFI is used for 24p content. In other words, every original frame is repeated 4 times, but with every other frame replaced with a dark frame. That leads to 48Hz flicker, which is objectionable. With 144Hz processing, one would repeat every original 24p frame 6 times, but replace every other frame with a dark frame. At some point, how fast the liquid crystals respond likely becomes a limiting factor.
Importantly, all these schemes only cost, at most, 50% light output. Which is fine by me for the increased motion resolution one can get. It helps that I have a High Contrast HP (2.4) screen.
I'm very curious if any of this has been updated with the newer models. I relayed my concerns about DFI to Sony & an engineer did mention that they're aware of the desire for 144Hz. I'm hoping this means that they're aware of both the desire for 144Hz with 3D
(which leads to 72Hz flickering -- which'd made 3D more palatable; currently it has far too much flicker) as well as with DFI
. I'm hoping that once they implement 144Hz for 3D that they'll also implement it properly for DFI. It'd really make Sony projectors quite the desirable option due to the increased motion resolution!
P.S. Ericglo thanks for the recommendation on the new Spears & Munsil disc.