But film is scanned for dvd and hd disk use so it [Kell factor] doesnt apply.
That's reversed. Kell factor applies when images are sampled (film telecines, TV cameras) but not with non-sampled images (computer graphics, etc.). A telecine, used for DVDs, samples film images while optically scanning them. -- John

appreciate the info.

Why can't a 1080p projector display 720p 1:1? Can't it just display a 720p image window boxed into 1080p? Then it would be zoomed out to maintain the same image size.

Because then you would effectively be using about half of the projectors light output to display the 720P picture. The difference in light output would make the 1080P picture look clearer, and mess up your brain's perception of detail.

If you're starting with 1080 source material, it has to be compromised at some point in order to display on a 720p device, either through an extermal VP or the internal scaler of the projector. Isn't that the whole point of this exercise - to find out if this compromise can actually be detected by our eyes?

Yes, but in practice, it's a question of whether you can tell the difference between a 1080P source on a 1080P display, and a 1080P source on a 720P display. In practice, the 720P display is compromised in two ways: Less resolution, and downscaling artifacts. So if we want our comparison to have any real-life relevance, this is the way we should test it. However, in real life, we don't have two projectors that are _exactly_ equal, except for resolution, so in my opinion the best way to do this is downscaling a 1080P source to 720P and upscaling to 1080P, and comparing this to directly mapping the 1080P source to the display. If you start comparing 1080P source/1080P display vs. 720P source/720P display, you are comparing much more than whether it makes a difference to have a 1080P display or not. I sincerely believe that the difference between 720P/1080P sources matters more than the difference between 720P/1080P displays.

The way I see it, there are two really interesting discussions to make out of this issue:

1: Say you have X.XXX dollars to spend on a new projector. Which is the better choice: The best 720P available at the price, or the best 1080P available at the price. This is an interesting discussion, since the choice might for instance be Sim2 HT3000 vs C3X Lite. Which of the two is, in practice, better at displaying a 1080P source?

2: The theoretical discussion: Does a 1080P display make a difference, and when - given that all else is equal. The best way to test this is in my opinion the one described above.

The only question that remains, is: Does question #2 really matter in real life? Aren't we all actually concerned about question #1? To me at least, the bottom line is: Which projector gives the best experience for the invested $'s. So, how interesting is it really to find out what the difference is between an AE900 and an AE1000? Isn't it a lot more interesting to find out what the difference is between an AE1000 and, say, a Samsung SPH710? (which, at least in my country, is the same price). Not an easier question to answer, but in my opinion a lot more interesting.

To me at least, the bottom line is: Which projector gives the best experience for the invested $'s. So, how interesting is it really to find out what the difference is between an AE900 and an AE1000? Isn't it a lot more interesting to find out what the difference is between an AE1000 and, say, a Samsung SPH710? (which, at least in my country, is the same price). Not an easier question to answer, but in my opinion a lot more interesting.

maybe, but maybe not. My question was whether the current generation moving to 1080P was better than my last generation at 720P. My answer was a resounding "no" given the out of pocket. However, it was not so much a cost versus benefit factor. i was already prepared for the cost, what I saw was literally no benefit.

I have resigned myself to the fact that I may have to get another 1080P unit and see the other benefits of that projector over my very admirable (for the price) Panny AE900 with it's excellent implementation of smoothscreen. What my thinking as of today is that I will get something that gets me the contrast, lumens and "punch" that will outstrip what I have. The 1080 factor will only allow me to do without smoothscreen (and get better sharpness I hope) without seeing pixels.

I have seen both projectors at the same time and there is a big difference between them, both in regards to contrast and resolution of picture. I would guess if so you sat far enough you wouldnt see a difference but I was sitting a pretty normal distance and I could definitely see a difference and I would call it a wow factor

I'll be surprised if I don't see a difference. I paid close attention to what I saw tonight. We watched Casino Royale (with anamorphic lens) and in lesser detailed areas I can see pixels and sde. It's pretty minimal, and I only see it because I look for it and because I am sitting closer than anyone else, it can be visible sometimes. It doesn't ruin the experience, but it will be nice to reduce or eliminate it. If and when I get a 1080p I'll see whether or not I notice a difference in resolution and detail, and sde. I'm bet I'll see a difference.

I have seen both projectors at the same time and there is a big difference between them, both in regards to contrast and resolution of picture. I would guess if so you sat far enough you wouldnt see a difference but I was sitting a pretty normal distance and I could definitely see a difference and I would call it a wow factor

10 feet, 100" screen, both on Cinema 1 calibrated only with Avia. No discernable dofference on regualr movie material via a Toshiba HD-DVD player outputting 1080i nor with HD material via Tivo Series 3 HD on several HD channels. 900 new lamp (replaced under lamp warranty three months ago) with 150 hours, 10000, new lamp with 0 hours.

Contrast may be better on the newer machine, but definitely no "wow" factor. As I have said before, I bought the 10000u and really wanted to see the big difference, but in the end couldn't justify it.

well, count yourself lucky that you don't see a difference!

I would, however, be most interested in finding out if you see a difference with the JVC RS1...

I wear glasses, so my vision is effectively 20/20. I saw a difference between 480p and 720p. I'll report any more experience I have later.

maybe, but maybe not. My question was whether the current generation moving to 1080P was better than my last generation at 720P. My answer was a resounding "no" given the out of pocket. However, it was not so much a cost versus benefit factor. i was already prepared for the cost, what I saw was literally no benefit.

I understand that fully, but then I have to ask: If you're willing to pay what it costs to upgrade to 1080P, to get a better picture - why aren't you willing to pay that same amount of money to upgrade to a better 720P, to get a better picture?

I have seen lots of people saying the same thing: They are willing to shell out the extra cash for 1080P, because they can justify the difference in cost because of the increase in resolution. Why, then, can't you justify a difference in cost because of better lens, better chips, better signal processing etc.?

In your individual case, I understand your point with smoothscreen, but at least to me, screendoor is a non-issue with 720P DLP. Depends on screen size, I guess.

I understand that fully, but then I have to ask: If you're willing to pay what it costs to upgrade to 1080P, to get a better picture - why aren't you willing to pay that same amount of money to upgrade to a better 720P, to get a better picture?

I have seen lots of people saying the same thing: They are willing to shell out the extra cash for 1080P, because they can justify the difference in cost because of the increase in resolution. Why, then, can't you justify a difference in cost because of better lens, better chips, better signal processing etc.?

I was willing. My 1080p projector, compared to my H79 720p projector, has a much better lens, better processing, more features and higher resolution. So I got a bigger screen and I sit closer. It all adds up in my opinion picture wise to a much better picture. Unfortunately, it also all adds up price wise too.

I understand that fully, but then I have to ask: If you're willing to pay what it costs to upgrade to 1080P, to get a better picture - why aren't you willing to pay that same amount of money to upgrade to a better 720P, to get a better picture?

I have seen lots of people saying the same thing: They are willing to shell out the extra cash for 1080P, because they can justify the difference in cost because of the increase in resolution. Why, then, can't you justify a difference in cost because of better lens, better chips, better signal processing etc.?

In your individual case, I understand your point with smoothscreen, but at least to me, screendoor is a non-issue with 720P DLP. Depends on screen size, I guess.

As I said earlier in the thread, I wonder if for many, that would not be the best thing (a better 720P Projector). I am going to audition a couple in the coming months and an RS-1 as well. Heck, I amy even go to a better screen ( I do have some limitations there as I have to have a drop down screen- my room does double duty).