HVR-A1 For Filmout?

[Frank Discussion]

Hello!
I am a happy owner of an HVR-A1U and have used Alan Robert's findings to great effect. Thank you!
But, I have a problem that is not directly addressed in the white paper on the A1/HC1. That is, the settings for use when filming for an eventual filmout.

Any suggestions on settings and/or workflow would be of tremendous help to me.

Here's how I have things so far:

I keep the A1 in HD 1080i mode. No Cineframe. Cinegamma on 1(?), low sharpness settings, black stretch ON, steadyshot off when on tripod/on when movement might take away gains in resolution, locked down to a shutter speed of 60... All in all, pretty much the settings you list for film look HD mode, except I have the sharpness cranked down a little lower.

Many, many thanks!

[Alan Roberts]

Hi Frank, I'd really not try to get a decent film look on the A1, it isn't up to it. That's regarding it s a professional camera. For consumer stuff, high days and holidays, it's great fun and makes nice pictures, but the restlessness that comes from the aliasing engendered by the inadequate resolution and cheap scaling really get in the way of making professional pictures. What you're doing is about as good as it gets, don't bother trying to push it any further.

[Frank Discussion]

Now I'm confused. The A1 has 4 times the resolution of the DVX100 or the PD150 yet there are dozens of movies using them. In fact, David Lynch just released his latest movie shot entirely with a PD150.

Am I missing something here?

[Alan Roberts]

Yes, you're missing something.

My DX100 has 3 ccds each of about 540x576 (I'm in PAL land) with precision offset of G from R and B, so it makes resolution up to about 700x500, according to my measurements. Recording is on DV, 720x576, so it doesn't even fill that bandwidth althougg what it does record is fairly free from aliases. The PD150 does rather better, because it has more pixels and does reasonably good filtering, so does the DVX100, and they cost a lot more.

The A1 has a single sensor, 1920x1440, of which 1920x1080 is used for HDV. In order to extract colour information from the Bayer-pattern pixels, there's interpolation needed. In the best cameras, that filtering is adatptive, but the cheaper ones do it less well. So, you get resolution up to around 1400x800, but the resolution above 960x540 is polluted by asliased frequencies, and this gices you get over-active pictures with twinkly edges. The A1 costs a lot less than the PD150, and you get what you pay for.

[Frank Discussion]

Well, that really screws the pooch for me. I may not recover from this one. Ugh...

[SimonMW]

Alan, I though DV was only actually recording 500x576, but expanded to 720x576 on playback much like HD 1440 goes to 1920?

[Frank Discussion]

Well, it appears that the Sony interpolation scheme on the A1U works better than thought as I just got off the phone with Duart, a New York company that is known to do quality filmouts (I found out about them through an article in DV Mag where they sis some filmouts using several companies) and they say they have done filmouts that far surpass the PD150, describing the difference as "like day and night". They are one of the best in the country and show filmout footage from the A1U every week (unfortunately I'm in California and can't see it for myself). The engineer was adamant about good lighting, locking down the shutter and avoiding crushed blacks and watching the highlights. He strongly recommended using a CRT monitor and a waveform monitor such as included in DV Rack.

Since I know you know what you're talking about, I can only guess that Sony's interpolation scheme does something cute, as they are always doing odd stuff with their DSPs, etc. (witness the new V-1)... This one seems to work.

[Alan Roberts]

Simon, I'm not sure what goes on inside the compressors, but I've measured resolution via DV that goes close to 720, and in HDV that goes close to 1440, so I suspect there's no re-sampling in either.

Frank, I'm only going on what I've measured, I usually ignore what the spec says and invetstigate for myself. The A1 is not a patch on a decent DVCAM unit, and all HDV is rejected as being unfit for HD broadcast by major broadcasters. The Z1 is not regarded as an HD camera, and it's far better than the A1 (I've measured both, and own an A1). I woildn't consider trying to make a quality programme on an A1, it isn't up to it.

[Frank Discussion]

Thank you so much for your kind help.

[StevenBagley]

Alan, I though DV was only actually recording 500x576, but expanded to 720x576 on playback much like HD 1440 goes to 1920?

If you are thinking of the DV is 540 lines resolution, SVHS is 400 etc, you have to remember that is lines across a circle that's radius is the same as the picture height, and so only covers 3/4 of the width of a DV image and 3/4 of 720 is...

Steven

[SimonMW]

Thanks Steven. :)

[Alan Roberts]

Steven's just described the principle difference between tv and graphics. In a tv system, the image has to be able to move, so the pixel count in each direction must be more than double the resolution (in cycles/width or height). This is the Nyquist limitation, that there must be at least two samples per cycle. But, in graphics, all pixels are individual, so the full raster resolution is available, but the image can't be moved without there being naqsty rippling in edges caused by breaking the Nysquist criterion.