1080i vs 720p

Tech Diver wrote on 11/2/2006, 6:27 AM
As I observe and/or participate in the HDV discussions in this forum I notice that most folks that work with HD, use the 1080i format far more often than the 720p format. My camera also shoots HDV at 1080i but I am looking very seriously at the JVC GY-HD110U which shoots 1280x720 24p/25p/30p and 720x480 24p/60p/60i. Is there any reason why I should stay away from 1280x720? Note that I live in the U.S. and shoot only NTSC.

Comments

Laurence wrote on 11/2/2006, 6:51 AM
Well IMHO, 1080i looks better, maybe not to independent film technicians, but to the average guy browsing HD Tvs at the local Best Buy, there is enough difference that an average consumer can see it.
BrianStanding wrote on 11/2/2006, 7:06 AM
In a couple of years, this discussion will likely be moot, as I suspect everything will eventually move to 1080p.
Spot|DSE wrote on 11/2/2006, 7:17 AM
If you're shooting for broadcast, 720p will always be upscaled to 1080i by 99% of the broadcasters. If you're shooting for corporate clients, you can do whatever you want and control the situation, but most monitors/displays will still be rescaling the image.
I've written an article a couple years ago, now slightly outdated, that addresses this subject in a slightly different view. Read it here if you'd like.
Tech Diver wrote on 11/2/2006, 10:09 AM
Thanks for the input. Spot, your article was especially helpful.
Peter
GlennChan wrote on 11/2/2006, 2:01 PM
DV magazine has a comparison of 4 different HDV cameras:
Canon XL H1, JVC GY-HD100U, Panasonic AG-HVX200, and the Sony HVR-Z1U

here (registration required)

The cameras themselves make a difference in the recorded resolution; the JVC actually does very well.

2- I don't think that shootout compared what conversions happen to the footage. 720-->1080, interlaced <--> progressive.
Bill Ravens wrote on 11/2/2006, 2:19 PM
I wrestled with much the same question. In the end, the price, followed by the camera's ultimate flexibility, prompted me to get an HD110. In the two weeks I've had this camera, I can truly say I'm quite happy withthe purchase. Camera ergonomics are the best I've seen. Connect HD resizes the 720P format to 1080i, if you wish, however, I've seen no need to do this. The scene files available from others using the HD110 are nothing short of stunning.
Spot|DSE wrote on 11/2/2006, 2:54 PM
2- I don't think that shootout compared what conversions happen to the footage. 720-->1080, interlaced <--> progressive

It didn't compare that factor, which is critical, IMO, as almost everything broadcast excepting a few, is 1080.
The shootout at DV.com has been more or less declared by several as tainted; the one from DVInfo.net was significantly more exacting, and well documented. Results were overall similar, however.
Properly handled, 720p upscales quite nicely, but at the broadcast level, it may well not be properly handled. 720p has nearly 30% greater horizontal resolution than 1080i, which helps a great deal. On the other hand, we've also now got very affordable 1080 p24 and p30 that looks great.
Jay-Hancock wrote on 11/2/2006, 4:47 PM
Spot, I'm a bit confused. As I understand it, 1080i is 1440 pixels wide, whereas 720p is 1280 pixels wide. How does 720 get 30% more horizontal resolution? (I know that a 1080i field is only half height, but I thought it was full width [1440, not 1920, for HDV]).
Spot|DSE wrote on 11/2/2006, 7:18 PM
Because 1080i is really only 540 complete lines of resolution.
the holy grail which we all seek, is 1080p in whatever flavor, but 1080p60 is the next "great" step in our industry.
1080 is also 1920 pixels wide; HDV is 1440, and the broadcast/compressed satellite signal is 1440, but the display is actually 1920x1080.
Jeff9329 wrote on 11/3/2006, 8:05 AM
Tech Diver:

The JVC HD1XX & newer models are a very robust camera with excellent PQ. I studied & manipulated a ton of footage from this 720P camera (which is available off http://dvinfo.net/conf/forumdisplay.php?f=98) in comparison to the Canon H1 (1080i, hundreds of sample clips also available there). Both are ENG style and very good. To me both are very good, but I prefer the 720P. Granted my first HD camera was the GR HD-1, so I was very familiar with the PQ & format.

The ONLY downside to 720P is the lack of cameras available. Your main choice is JVC and the ENG style. As long as we keep watching sports in HD, 720P will be alive and well, as all sports channels & events are native 720P due to the inherent advantages over 1080i.

Laurence:

When you or anyone is browsing the Circuit City, how do you even know what resolution (or bitrate for that matter, 1080i is broadcast at the same bitrate as 720P) image you are viewing? You don't. So how could you say one looks better than another? You can't. Also, the native resolution of almost all plasma and most LCD monitors is 1280X720 or less. You can't even see 1920X1080 (or 1440X1080) on 95% of current monitors.

As far as broadcasters upscaling 720P to 1080i, that is not done at a network feed level but sometimes at the service provider level and more commonly at the set top box level. Off my satellite feed I see sports in 720P and most other in 1080i (my monitor reports signal type). On my cable box, it scales everything to whatever you set it to. However my cable box has a 1394 port which I connect to a DVHS input. My DVHS shows that the raw streams vary dramatically in bitrate and also vary between 720P & 1080i about equally. Its the cable box wanting to make everything 1080i.
Tech Diver wrote on 11/3/2006, 10:54 AM
A few months ago I was leaning more toward getting the Cannon XL-H1. But after reading in their manual how they simulate 24p I began to have reservations. Coming into video through many years of film work, I am looking for something that is the digital equivalent (more or less) of cinematography (shooting film is very expensive). The JVC GY-HD110 is appealing to me more and more as I continued to investigate. Furthermore, I am finding several places that are selling it for around $4700 and one shop that has them for $3500. Admittedly, it would be nice to occasionally have 1280x720 60p with the JVC GY-HD250, but that unit currently goes for around $10k.
Yoyodyne wrote on 11/3/2006, 11:13 AM
Just to chime in :)

I own an JVC GY-HD100 and have worked a ton with the Z1. Both are great cameras and produce amazing images - If your coming from a film background and used to a more "traditional" camera the JVC might be a better fit. Having an actual lens (and focus assist) was what sold me on the camera.

Also, I don't know if you have read about this but JVC is coming out with a 16mm lens adapter/re-imager that mounts directly to the camera and will allow you to use 16mm primes, etc. It's called the HZ CA13U. From what I have read this is an optical adapter with no spinning glass like the redrock m2 - and "supposedly" it will allow you to get a 16mm depth of field. Having the option of putting really nice glass directly on this puppy and getting a nice DOF would be a minor miracle - it is supposed to come out next month. I guess we will see if it's what they claim soon enough...but they sure have my attention! Google JVC HZ CA13U and you should come up with more info.

Good luck -
Bill Ravens wrote on 11/3/2006, 6:56 PM
The physics of optics dictates that it's absolutely impossible to increase the DOF simply by using a 16mm, 35mm or any large format lens on a 1/3 inch sensor. No can do, Yoyodyne. What may have you confused is that, yes, indeed, you increase the apparent DOF, however, you simultaneously increase the magnification factor by the same amount. So that by the time you move back far enough away from the subject to fill the frame with the same field of regard, your DOF is back to where it was with the standard lens.

I'm afraid there is one and only one way to get 16mm or 35mm DOF on a 1/3 inch image format, and that's to use a spinning or vibrating ground glass screen, together with an achromat optic. No other way Jose!

The only reason for using a 1/2 inch or 16mm lens adapter on the JVC HD100 is to be able to use some very fine glass on the image capture device.
Yoyodyne wrote on 11/3/2006, 7:47 PM
Thats what I thought as well Bill - but that's not what they were saying at NAB. This is a post from from Tim Dashwood over at DVinfo (hope it's o.k. to post this):

"HZ-CA13U PL mount adapter. – This is more than just an adapter – it is a re-imager. The end result is a field-of-view of Super-16 using PL mount lenses. The image will be inverted and flipped, but the two new cameras will unflip the image ON TAPE. This is a BIG DEAL and something that was on my wishlist for ages. My goal today is to find out how this thing actually works since it supposedly does not have a ground glass/focusing screen. There is not alot of information on this thing... not even a MSRP."

Now I don't know how this can be possible either, but I sure am curious. My sense is that it's just a PL mount adapter for the camera with good optics. That would be great but if they can deliver on the "field-of-view of Super-16" that would be super sweet.

pic
Bill Ravens wrote on 11/4/2006, 6:04 AM
if what you heard is right, all I can say is WOW!! the preliminary pricing I've seen for the JVC adapter is around 700-800 bucks. That's competitive with the Rock Micro or Letus imaging devices, It would, indeed, be sweet. Just as a sidebar, HDrack will invert those images if one selects the right switch.
Tech Diver wrote on 11/4/2006, 7:24 AM
For those of you who have bought the JVC GY-HD100U or HD110U, I would be interested to hear where you purchased your cameras and what you paid. Although I see some really good deals out there, I am very concerned about bargains. All too often customers are cheated by bait-and-switch tactics and the like.
John_Cline wrote on 11/4/2006, 7:41 AM
For my money, B&H Photo is the most reputable of all the mail-order equipment dealers.

B&H Photo

John
Bill Ravens wrote on 11/4/2006, 9:22 AM
I bought mine from www.markertek.com
These guys have a 5 star rating and the cheapest price I could find. Markertek has been a supplier of mine for a few years and has never disappointed me.
jwcarney wrote on 11/5/2006, 7:54 AM
I got mine at ZGC, excellent customer service and they are right down the road from a JVC service center.