Here is what Art said about the blacks of the JVC HD250 vs. the Optoma hd8300:
In terms of blacks, on really dark scenes, the two seem about comparable. On mixed brightness scenes, the JVC (as expected) which doesn't use a dynamic iris, will show blacker blacks. Of course you appreciate great blacks most on those overall very dark scenes without any bright areas. (That folks is why we use this night train scene, as one of our most critical test images.)
Later on he side-by-sided the hd8300 and said he was surprised to see that it beat the blacks of the Panny 7000. You have to remember people are reviewing black levels in relation to price, for this price the hd8300 isn't great at blacks compared to some projectors, and note that the few DLP's that were good at this are no longer in the running as none of them had 3D. The Optoma hd8300 puts out respectable brightness, I don't see why it wouldn't be as bright in 3D as the Sony?
Also, Art had a pre-production hd8300 I believe and the other reviewer may have as well, other reviewer numbers I saw were even brighter than Art's, and the best modes are a little brighter than the Sony hw30 from the numbers I have so far, although somewhat incomplete on this PJ.From ProjectorCentral.com brightness measurementshttp://www.projectorcentral.com/opto...ge=Performance
Its Cinema mode (Optoma hd8300), which has the best color and contrast performance of all of the projector's preset modes, measures 832 lumens in standard (low) lamp mode with the lens at its widest angle setting. Bright lamp mode increases lumen output by about 20%, bringing Cinema to 996 lumens. Brightest mode was 1200 lumens.
Now how the IRIS works is another story, never seen it, it could be too intrusive.
I don't trust on/off readings at all anymore unless they come from specific places, too many people still don't take them right, even respected reviewers. Some people measured an RS-45 at 70,000:1, others measured it at 25,000:1. It's the technique some are using is invalid because their meters aren't accurate enough to get the floor, and they aren't compensating correctly or estimating. It's easier to trust lower Native readings than higher, but I still don't trust them. Really the RS-45 is 50,000:1 just like JVC says, I measured it at 48,000:1, Tom Huffman measured it at 52,000:1.